iluminação para orquídeas(1)

8/6/2019 Iluminao para orqudeas(1)

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Camera Light Metering & Your Orchids

From The Bulletin of The Vancouver Orchid Society, December 1994 via. the Mary's PeakOrchid Society Newsletter, February 1995

For those interested in measuring the light in their growing area, there was a posting on measuringfootcandles using the light meter in a camera. The information was originally given in the May 1968AOS bulletin, but it might be useful to repeat it for all of us whose orchid history doesn't go back thatfar. The procedure is as follows:1. Set you film speed at 100 ASA (or 50 ASA, or 25 ASA - see point 4).2. Set you exposure time to 1/125thof a second.3. Place your camera on your plant bench, point the lens at the light source, and note the f-stop.4. Use the chart below to read off the foot-candles. If you have a lot of light, you may need to adjustthe film speed to 50 or even 25 ASA and repeat the process.

Foot-candles

f-stop 100 ASA 50 ASA 25 ASA1.4 16 32 64

2 32 64 1282.8 64 128 250

4 128 250 500

5.6 250 500 1000

8 500 1000 200011 1000 2000 4000

16 2000 4000 8000

22 4000 8000 16000

GROWING ORCHIDS IN THE HOMEPART 1

(by Peter Holmes)

This is the first in a series of articles about growing orchids in the home. As space is limited, I amgoing to concentrate on problems and ideas directly related to home growing. For general plant andculture information, please refer to the books and periodicals in a library. The Oregon OrchidSociety booklet, Your First Orchids and How to Grow Them, and Rebecca Northen's book, HomeOrchid Growing, for example, are excellent.

Windowsill Culture - Your growing area needs to receive sufficient light, be free from cold or hotdraughts (such as from a heating vent) and not be close to an artificial light source such as houselighting or street lamps, as these may inhibit blooming in some plants. Without sufficient light, your

orchids may bloom for you the first year in your care but not after. If you already have an areawhere house plants such as African violets grow and bloom well, then you can include orchids inyour collection successfully.Most orchids require filtered sunlight to do well, the amount of shading required depends on thetime of the year, direction of sun and type of orchid. In the summer, morning sun through an Eastwindow is beneficial. A West window can be hot, so shade carefully. In the winter, a Southernexposure is best. It is possible to grow some of the cooler growing orchids such as Odontoglossumsand plain-leaved Paphiopedilums in a North window but only if it is large and unobscured by trees,etc. Such plants require relatively little light.For orchids in East, South or West windows, shade enough so that the leaves are never more thanslightly warm to the touch, otherwise they may burn. Movable shade in the form of sheer curtains orblinds is best so that it may be adjusted to admit more light on dull days. If the correct amount oflight is reaching your plants, they will be a medium to light green color, rather than dark green. A

reddish tinge in the leaves indicates that the light level is the maximum permissible without riskingleaf burn. Please note that it takes a while for the leaves to respond to different light levels, whereasa burn can happen in a few hours. Also, plants that are grown in full winter sun should be watched
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carefully in the spring as the sun gains strength. I once grew a group of orchids on a 3-tier benchsloping toward the sliding glass patio door with two layers of sheer curtain protecting the less lightdemanding plants and 1 layer for the others. The whole bench was within 3 feet of the window forthe best light but no leaves were allowed to touch the glass in the winter for fear of freezing. Byusing benches in this manner, quite a few plants can fit into a small space. One problem of growingindoors is often the lack of space so try to obtain plants that will be small in size when mature.

Orchids to Grow Indoors - The most popular orchids for indoors are Cattleya, Paphiopedilum andPhalaenopsis, although many other plants can be grown. Try to avoid the large florists' Cattleyasbecause of space and the difficulty of blooming them consistently. Cattleya hybrids with Sophronitis(So.) and/or Laelia (Slc., Lc., Pot.) are often smaller plants that bloom well. Slc. Hazel Boyd is agood example. Similarly, the white and pink Phaleonopsis often develop into large plants. It mightbe better to grow hybrids with Phal. violacea, marine, etc. in the background. In Paphiopedilums,the species niveum, concolour, bellatulum, etc. are all small and have been used to create manylovely hybrids. Rebecca Northen's book Miniature orchids gives many examples of plants to grow ina limited space. It is possible to grow larger plants such as Cymbidiums indoors during cold weatherand summer them outside but be sure you want to donate all that space to just one plant! You couldgrow many miniatures in the same area !The next installment will talk about setting up your growing area.


(by Peter Holmes)

This is the second in a series of articles about growing orchids in the home. As space is limited, Iam going to concentrate on problems and ideas directly related to home growing. For general plantand culture information, please refer to the books and periodicals in a library. The Oregon OrchidSociety booklet, Your First Orchids and How to Grow Them, and Rebecca Northen's book, HomeOrchid Growing, for example, are excellent.

The indoor growing area should receive sufficient light as mentioned last month, and should not bewhere warm air from a radiator or heater vent reaches the plants. Cold draughts are to be avoided

also, although fresh air, when the outside temperature is high enough, is good for your plants.Warm growers such as Phalaenopsis don't like temperatures much below 70F during the day,whereas Odontoglossums will be happy with 60-65F and lots of fresh air.It is tricky trying to accommodate a mixed collection of cool, intermediate and warm growers in thesame area so beginners are advised to stick to one group best suited to their conditions. Later, youmay find other areas of your home, such as the basement, are suitable for cooler plants forexample. A Max/Min Thermometer, available from nurseries for about $30, is useful as it registersthe high and low temperatures for a given period so you can adjust your ventilation and heating asrequired. All orchids, other plants and humans (!) are healthier with a temperature drop of about10F at night and, indeed, this change in temperature is essential for blooms to develop in manyorchids.Humidity is often a problem in the home in the winter and. again, it is healthier for all concerned ifthe relative humidity is kept at approximately 50% during the day. With the temperature drop at

night, the relative humidity rises to about 60% which is good for plants. A Hygrometer may bepurchased to help you determine the humidity in your home. Cheap ones are not that accurate butwill give some indication. If the humidity is too low there are several ways to raise it in the growingarea. One is to group plants including ferns and other house plants together as they transpire waterduring their growing process thereby increasing humidity. Plants may be stood in trays filled to adepth of about 2" with gravel. Red lava rock is excellent as it is somewhat porous drawing up thewater which you put into the tray so that its level is just under the stones' surface. The porosity ofthe rock and its many surfaces allows the water to evaporate up around the plants.Never let the plants stand in the water as the roots may rot in time. Standing plants on inverted potsin a tray filled with water is not very effective because the surface area open to the air is greatlyreduced without the stones. You may find that after watering your plants, the level in the trays risesabove the stones. Use a plastic baster to draw out the excess water, rather than moving all yourplants to tip the water from the tray. Trays can be simple plastic seedling flats without holes, 11" x

22", and available from nurseries for about $1.30. For added strength, put one flat with holes insideone without holes, then add the stones. If you decide to use decorative white stones, these can becleaned from time to time with ordinary bleach which is then rinsed off carefully.
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Misting your plants adds temporary humidity but be careful not to let drops of water form which mayrun down into the new growths of your plants and cause rot. Mist early in the day to ensure thefoliage is dry by nightfall. Misting is probably best avoided on thin leaved orchids if the humidity isover 50%. Plants with good root systems can absorb all the moisture they need through their roots,provided the compost they are growing in is kept evenly moist. This is best achieved by using amoisture retentive mix containing peat moss and/or pumice or lava rock. Whereas in a greenhouse

with its higher humidity it is acceptable to let plant roots dry out for a short time, it is stressful forplants grown in the home. Try to keep them damp, not wet and not dry during their growing period.They may be allowed to dry out more at the end of their growth cycle to encourage flowering.More about watering and feeding plants grown indoors next month.


(by Peter Holmes)

As your plants will be growing quicker in the brighter light of summer than during the winter, feedingshould be adjusted accordingly as they will not be able to assimilate food during dull winter days.High nitrogen formula such as 30-10-10 (N being the first number) is needed for plants grown in firbark although, if you use a mix where bark is 50% or less, a balanced formula, ie. 20-20-20 is

better. Check the label of the fertilizer you use to ensure that it contains trace elements such as ironpreferably in a chelated form which is readily available to the plants. Fish fertilizer should not beused exclusively as it has to undergo several changes over a period of time in order to beassimilated by the plants. Powdered fertilizers are fine but be careful not to feed too much at once.Little and often is best, about 1/8th of a teaspoon per gallon for four out of five waterings, the fifthcan be plain water. This rate of application will not harm the root tips of your plants.During the winter you may feed two out of five waterings unless you supplement the daylight withartificial light. This use of lights can greatly reduce the problem of trying to grow orchids indoorsduring the winter. Even on sunny days the day length is too short to help the plants grow well.Artificial light is an excellent way to encourage your plants to grow all the year. It is a way to growseedlings on to maturity much quicker and as most orchids grown in the home come originally fromthe tropics, it is a way of duplicating their natural day length.Fluorescent lights are the most commonly used although Grow-Lux markets floodlights which are

useful if you only have a few plants. Unless your window faces south and gets the winter sun, itmight be a good idea to try a 4 ft. fluorescent light fixture over your plants. The only problem is thatthe light level drops quickly the further the plants are from the tubes so the light should be placed towithin a few inches of the plants. I grew cattleyas and phalaenopsis successfully for several yearsusing two light units side by side with two tubes in each over my plants. I built a structure especiallyfor them and had three levels of lights giving me a 4 ft. x 4 ft. growing area at each level. The threelevels also created three temperature ranges for the plants, so cooler growing odontoglossums, etc.grew on the floor level, the rest on the upper two. The use of lights is a very viable way of growingorchids and I have been lucky enough to win several trophies and gained two AOS flower qualityawards for plants I have exhibited.Lights can be fitted into any area where there are no windows, or in places which are little usedsuch as basements. My present setup is in an enclosed room where I can control the temperatureand humidity.

The secret of using lights, especially where they are the only light source, is in choosing the rightkinds of tubes. First, 2 ft. tube units are too small and don't give of sufficient light for sustainedgrowth although they may be used to display plants in bloom for a short while. It is best to stick withthe 4 ft. length unless you really are going to illuminate a large area in which case the 8 ft. lengthmay be better. Tubes give of the most light towards their centers and less at the ends so the 8 ft.tube does give a larger effective growing area. If you use 4 ft tubes, use at least two side by side,although 4 is better for a total of 160 Watts. The double light units can be spaced 6 inches apart tobroaden the effective growing area to about 4 ft. x 4 ft. If you are going to grow mostly cattleyas andother orchids requiring brighter light, it would be better to use six tubes or 3 double units side byside to give enough light. If you buy units without reflectors they are cheaper and you can makereflectors from tin foil which works well.I will get into details of what tubes to use and how to set up the light garden next month.Peter Holmes


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(by Peter Holmes)

Types of Fluorescent Lights and Their Uses

First, some discussion on the light spectrum and how it affects plant growth.

Plants need a balanced light for best growth, that means, they require BLUE light (wavelengthapprox. 430 nanometers) and RED light (650 nanometers). They also need FAR-RED light (710nanometers) to initiate budding and flowering. Plants grown in a predominantly BLUE light such asthat emitted by COOL-WHITE tubes will be short, stocky plants that do not bloom well, if at all.Plants grown under the RED light of INCANDESCENT bulbs will be tall and spindly. An artificiallight source that contains both the BLUE and RED parts of the spectrum will produce the mostnatural growth. The first successful source was a combination of COOL-WHITE (CW) tubes andINCANDESCENT bulbs mounted in the same fixture. 2-15 watt bulbs can be used with 2-40 wattCW tubes to provide a balanced light. Use clear incandescent bulbs for the best light transmission.The problem with this setup is that INCANDESCENT bulbs are very inefficient users of electricitywhich produce lots of heat instead of light, and this heat can burn plant leaves. The light is alsolocalized in the area of the bulb so some plants receive more of the RED part of the spectrum thanothers. Therefore, several companies have produced "plant-growth" tubes which can be used by

themselves, are cooler and less liable to burn leaves and are more efficient. They are all variationsof regular tubes with different coatings inside the glass to alter the spectrum of light emitted.However, what is little known is that there are many other tubes available from specialist lightingstores (such as Albrite Lighting in Burnaby) that can be used by themselves or in combination toproduce the spectrum required by plants. All tubes have their name printed on the end of the glass,or it may be abbreviated ie. COOL- WHITE (CW). These names are standard throughout theindustry. So we have WARM-WHITE (WW), WARM-WHITE DELUXE (WWX), COOL-WHITEDELUXE (CWX), NATURAL (N), DAYLIGHT (D), GRO-LUX (GL) andINCANDESCENT/FLUORESCENT (I/F). The chart below shows the relative outputs of differentparts of the spectrum for each tube (courtesy of GTE Sylvania Bulletin 0.262)BAND NANOMETERS CW WW D W CWX WWX N I/FGL

% % % % % % % %

%ULTRA VIOLET 380 1.7 1.5 2.1 1.9 2.1 1.8 2.1 0.71.42VIOLET 380 - 430 7.6 5.2 9.6 6.4 7.8 5.3 7.6 2.39.75BLUE 430 - 490 21.0 13.1 28.0 16.0 18.8 11.8 16.7 7.527.3GREEN 490 - 560 24.8 20.6 27.4 23.2 24.0 23.8 20.9 20.114.1YELLOW 560 - 590 18.4 23.5 14.5 21.1 11. 9 15.4 12.0 13.41.43ORANGE 590 - 630 17.9 24.3 13.2 21.1 16.6 20.5 17.5 21.86.1RED 630 - 700 8.6 11.8 5.2 10.3 18.8 21.4 23.2 34.239.9

TOTAL - 100% ON ALLThe chart omits the FAR-RED part of the spectrum (730 nanometers) but most of the tubes havinga large percentage of RED will have some FAR-RED as well (ie. CWX, WWX and WW). TheIncandescent/fluorescent tube duplicates almost exactly the color of regular INCANDESCENT bulbsand is an excellent source of RED and FAR-RED for plant growth. It is also useful in domesticlighting situations for those who would like to combine the efficiency of tubes with the "look" ofINCANDESCENT bulbs. Some of these tubes are quite a bit cheaper than "plant-growth" tubeswhich may be a consideration if you are using many lights in a large area. Also, I find that GRO-LUX tubes bother my eyes a little and tend to alter leaf and flower colors too much. Some peopleprefer the GRO LUX "look", so I will leave the choice up to you. I have used combinations of CWand WWL, CW and I/F and CW and GL WIDE SPECTRUM and all have worked well. CWL and Nmay be used by themselves. The important thing is to have sufficient BLUE and RED light so theplants will grow strongly, it does not have to be of equal amount. You must have some FAR-RED


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for flower production. Regular GRO-LUX tubes are deficient in this respect but GL WIDESPECTRUM tubes are fine.Peter Holmes

GROWING ORCHIDS IN THE HOME

PART 5(by Peter Holmes)

More on Fluorescent Lights and Their Uses

Other tubes similar in color and performance to GRO-LUX Wide Spectrum Include AGRO-LITE amdGRO and SHO. They all appear pink to the eye and alter to some extents red and blue colors.Another group of lamps emits a white, wide spectrum light looking very similar to daylight, theseinclude VITA-LITE and TRU-BLOOM. But they are hard to come by unless ordered from the U.S.As they do look "white" to our eyes, they emit a fairly high percentage of light in the part of thespectrum little used by plants.The human eye sees mostly light from the orange/green part of the spectrum at around 550nanometers so lights that look the brightest to us may have little of the parts of the spectrum

required for plant growth (blue and red). Most people are familiar with the foot-candle (ft/cs) meterwhich measures light intensity. This instrument, however, is measuring the orange/green light thatwe see, not the parts of the spectrum required by the plants. If you take a reading at say, 6 inches,from a pair of 4 ft GRO-LUX tubes and compare it to a reading of 2 cool-whites, the cool-whites willmeasure appreciably higher. This does not mean that the output from the GRO-LUX tubes is weakoverall, it is only weak in orange/green light as seen by the foot-candle meter. From a plant's pointof view, the GRO-LUX is brighter.A foot-candle meter can be very useful in finding out where the brightest spots are in your growingarea so you can position your light loving plants accordingly. Please do not be put off by theapparent light requirement of some orchids as quoted in the literature, eg. Cattleyas requiring 2000ft/cs, Phalaenopsis 1000 ft/cs, etc. These are approximate MAXIMUMS that the plants can take insustained sun.It is quite normal even this far North of the equator to have 60% or higher shade over a greenhouse

in the summer. This means that plants may receive 3000 ft/cs or more for short periods when thesun is overhead in the summer but the figure drops drastically as the sun lowers during the day andis much lower in the spring and fall. You may only be able to manage say 600 ft/cs or less with yourfluorescent tubes but the light is sustained all day long, all year long, which is why plants do well.Orchids in greenhouses have to be grown "hard" here in the summer to make up for dull winterdays of little light. We don't have this problem under lights.It is important when using artificial light to ensure that as much light as possible reaches yourplants. The first thing to remember is that tubes wear out slowly and should be replaced long beforethey go black at the ends. I would suggest every year or 18 months. It is a good idea not to changeall the tubes at once, rather do them one at a time a couple of weeks apart. This reduces the stresson the plants as new tubes are brighter than rated output for about 100 hours. You can date yourtubes with a felt-tip pen on the end of the glass.Reflectors are a good idea. I make mine out of heavy tinfoil, simply fold it over once for strength, cut

off about 3 ft 10 inches and insert between the tubes and light unit, then fold down as required.Considerable light is lost front and back of the unit otherwise.My units were hung on chains from the ceiling using large hooks. In this manner, the units could beraised easily for watering the plants underneath. Alternatively, you can leave the unit where it is,and have the plants on a trolley with wheels to be pulled out as required. If you use a pump sprayerof the type used for insecticides etc., the wand will fit in nicely under the light if you only have a fewplants.Peter Holmes


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(by Peter Holmes)

More on Growing Under Lights

Seedling flats without holes or cat-litter boxes (better check with your catfirst! ) can be used to stand

your plants in. You can use stones in the flats and fill the flats with water to just under the stonessurface to increase humidity. Most plants should be as close to the tubes as possible withoutactually touching them, otherwise leaves will burn. Check them frequently as the plants do grow!Plants requiring less light may be positioned at the ends of the tubes where the light is less intense.Short plants may be stood on inverted pots to reach the light.If you have two 4 ft. light units end to end, try overlapping the ends about 4", then you can get thesame light level over a distance of 6 to 7 ft. If you are using 4 tubes or more in parallel, which yieldsa stronger light, you may find you can increase the distance between tubes and plants a bit to allowfor flower spikes to extend properly. This increase in distance may also be necessary to preventplant leaves from turning too red from the light intensity. A reddish tinge in the leaves is about right,although some of my odontoglossum plants have scarlet leaves and still grow well. The catch is thatlight under these conditions is not accompanied by heat (if the leaves are not touching the tubes)which would be the case with sun in a greenhouse. It is heat that burns. Burning is the next stage

after reddening of the leaves although of course leaves will burn very quickly in sunlight before anyreddening may be apparent.Another indicator that your plants are receiving sufficient light is if a sweet sticky substance oozesfrom the plant leaves, bulbs, flower stems, etc. This is particularly noticeable on cattleyas. Thissubstance is sugar which is produced by the plant during growth and flowering. Only a certainamount is needed by the plant, the rest escapes through the leaf and pseudo bulb surfaces. Thissugar is unfortunately an attraction to a variety of pests especially aphids so be on your guard!If your plants have reddish leaves and some sugar is evident, then blooms are almost sure tofollow. The plant's flower spike may be quite long (often the case with odontoglossums) so you havetwo alternatives: Raise the light out of the way of the extending flower spike or lower the plant. Thislatter idea seems the best as otherwise all the plants in your collection under the light unit willreceive greatly diminished light. Spikes can take three months or longer to develop and your otherplants will not grow so fast during this time If you lower the soon-to-bloom plant, it will still have the

buds close to the light and this will aid their development. It is not advisable to move the plant toanother locality or put the plant in a window as this will almost certainly cause damage to the buds.They may even drop off! This lack of vertical space is one of the problems of growing underfluorescent lights. Three solutions are:1. Grow only those plants which have their blooms close to their foliage ie. some paphs, mostminiature cattleyas, some peals, etc.2. Use 4 or more tubes side by side to greatly increase light intensity and grow plants that don'tneed much light ie. odonts, paphs, peals, etc. These plants can then be grown a foot or more fromthe tubes giving room for the flowers to develop. Longer spikes can be trained on a piece of wire togrow sideways in a graceful curve rather than straight up towards the lights. If you use 6 tubes sideby side, you could have about a 2 ft. gap between plants and tubes.3. You could use alternative forms of lighting such as High Intensity Discharge eg. Metal-Halidelights which can be mounted high above the plants.Peter Holmes


(by Peter Holmes)

Still More on Growing Under Lights

DAYLENGTH. We now come to another potential problem area for artificial light growers and that isthe subject of day length. People with greenhouses grow their plants strongly during the long daysof summer but in the winter, when many of their orchids are producing flowers, their plant growthhas slowed down considerably. The plants are blooming from strength gained during sunnyweather. Any plant in a growth phase rather than a flowering one tends to grow softly and this softfoliage can burn easily when the sun gains intensity in the spring. Many enterprising greenhouse

owners use artificial lights to lengthen the winter days, give more light to their plants, which thengrow more strongly and bloom better. So the greenhouse owner and the indoor light gardener can


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alter day length at will. However, some orchids are affected by day length and need short days toinitiate buds. If you keep your days 14 hours long using lights, these plants may not bloom. Cattleyalabiata is one orchid species which needs days of 12 hours or less to bloom and many of its hybridsfollow the habits of their ancestor.Commercial cut-flower growers can control blooming of many orchids by either lengthening daysusing artificial means (not much light is requi red) or by shortening days if need be by covering

plants with a black cloth. Pointsettas are bloomed in this manner for Christmas. So if you have inyour collection an orchid requiring short days and your lights are on too long or if your grow lightsare switched off but a table lamp is switched on near the plants, they will not bloom. Perhaps thebest method to prevent this problem is to avoid these plants unless you are willing to cover themevery night for about a month when their growths are made up so they get 10 hour days.The reason for mentioning this is that if you do have an orchid which won't bloom and you see fromold spikes that it did bloom before somewhere else, day length may be the problem.To control day length and switch your lights on and off consistently, it is best to use a time switch.Simple ones plug into a wall socket and have an outlet for your light unit plug. If you have many lightunits, you can use different day lengths for different units if they are in separate parts of the houseand try to entice hard to bloom plants by moving them to your 'short-day' area. For optimum growthduring the summer, I would recommend a day length of 16 hours for mature plants and seedlings.Seedlings can stay on 16 hours all the year to speed up their growth. I can bloom odontoglossum

seedlings one year out of flask this way. Be careful though not to overdo the blooming of smallseedlings as it can weaken them. If the plant is strong with good roots, it does not set it back if youtake off all buds except one and cut it off as soon as you can see the bloom. I have noticed withodonts that plants with spikes cut off as they emerge from the sheath don't usually start a newgrowth again until after the time it takes to grow the spike and bloom if the spike is left on.I have experimented with 18 hour days on several hundred seedlings but noticed that they sufferedfrom this, looking pale and dehydrated rather quickly despite care with watering feeding, etc. Feedyour seedlings dilute fertilizer regularly as they need it to develop large bulbs. It is a lovely sight tosee the first shiny bulbs develop on a new group of seedlings!For mature plants and seedlings if you wish, you can go down by perhaps 1 hour per month to 12hour days during the winter. I noticed that with phals and odonts, many plants bloom consistently on16 hour days with no problem so I believe you can get excellent growth and blooms by this method.It is best to experiment. I believe some plants spike on shortening days, some on lengthening days,

you can try going from 16 hour days down to 12 hours in one go, keep them at that for a couple ofweeks, then go to 14 hours for a couple of weeks, then back to 12 hours for 2 or 3 months of thewinter.Peter Holmes

GROWING ORCHIDS IN THE HOMEPARTS 8 & 9

(by Peter Holmes)

...And Still More on Growing Under Lights

The altering of day length, as mentioned in the last article should only be done with caution as itmay encourage some 'difficult' plants to bloom but may inhibit blooming in others. Some artificial

light growers adjust their day length to follow that of the natural day length in their area, but as farNorth as we are, I believe it is better to keep 12 hours as the absolute minimum for most plants.Another caution is to not alter the light quantity or quality drastically when plants are in bud, ie. don'tsuddenly change all your tubes for new ones, or fit different types of tubes as the flower buds mayblast. Change tubes one at a time, a couple of weeks apart so the plants have time to adjust.When moving a plant for any reason, always return it to the same position relative to the lightsource especially if the buds are just opening, otherwise the flowers might be deformed. It istempting to turn the plant around if the flowers have opened, facing the tubes, but resist until theflowers are fully opened and hardened. It may actually be advisable to remove plants then as light-coloured flowers will sometimes take on a "blushed" appearance, darker flowers may fade if theyare left under the light unit, too close to the tubes. After all the flowers have opened properly, it isnice to display the orchid in the home, somewhere fairly cool. The blooms will last much longer thisway.

Plants that have finished blooming may be rested by putting them back under the lights, at thesame angle to the light, but at the end of the tubes if there is room. The rest period depends on the


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particular plant, watch for signs of new growth. Many hybrids don't rest and may even have newgrowths coming with the old blooms still out on the plant.FEEDING - Some people advocate using a "blossom- booster" fertilizer, ie. 0-20-10 or similarduring budding and blooming but I have not noticed any particular improvement in flower quality orquantity by doing so. Fertilizers need to be of a balanced ratio, ie. 20-20-20 to be best assimilatedby plants. A high nitrogen 30-20-20 is only required when using large quantities of fir bark which

actually consumes quantities of nitrogen during its decomposition. This happens with your barkmulch in the garden as well.After blooming and when the plants are growing again, you can resume your regular feedingprogram. If you are doing everything correctly you may get multiple growths on your plants,especially on miniature cattleyas, and your pseudo bulbs should be larger than last time.Incidentally, the act of removing flower spikes just out of the sheath to prevent a plant fromblooming may encourage multiple new growths to start. The plant puts its stored energy intovegetative growth perhaps out of frustration!In the case of monopodials, like phalaenopsis, the leaves should be bigger, unless already full-sizedand reasonably hard, not soft and flacid. Plants grown this way should have more and biggerblooms next time around.By studying descriptions of awarded odont alliance plants which I have divisions or mericlones of, Ihave found that I can equal the flower size and quantity of the awarded plant in nearly every

instance by using artificial light as the sole source of illumination, so the system does work. Toachieve these results or to grow orchids which demand very high light levels such as somedendrobiums and vandas requires alternative sources of light to the fluorescent tube otherwisesparse blooming will result. I am referring to the use of Metal Halide or High Pressure Sodium lightswhich are both High Intensity Discharge units. These lights are similar to fluorescent lights in thatthey require a ballast to power them. Different ballasts are required for Metal Halides and Sodiumlights. Obviously the ballast for a 1000 W light is larger than that for a 400 W. So you have todetermine which size and type of light you require for your own situation.METAL HALIDE OR SODIUM? - Metal Halide bulbs come clear or coated so actually there arethree choices. The clear MH produces a light close to that of the summer sun and its spectrumcontains far-blue, blue, red and far-red light. Coated MH bulbs give a light similar to that of the sunin fall or winter with a reddish tinge. The coating reduces the light output of the bulb, reduces theblue output and increases the orange. The Sodium light has very little blue, its output mainly coming

in the green, yellow, orange and red parts of the spectrum. This produces a distinctly yellow/orangelight. It is generally felt that if you have no natural light reaching your growing area, the clear MHgives the best result for growth. Either MH clear or Sodium may be used as supplemental lighting ina greenhouse with good results.As nearly all my orchids came originally from high elevations near the equator, I have had bestresults for growing and blooming by using MH clear lights in the 1000W size. Once I experimentedby using a clear 1000W for 8 months, then switched to a coated bulb, but noticed after a time thatgrowths were making up earlier and were smaller than anticipated.Please note that many orchid hybrids finish growths in about nine months. As a result, a collectionof 1000 or more plants will have orchids in various stages of development from just starting newgrowths to being in spike. So it is not really possible to juggle the light spectrums for best resultswhich may be done with say geraniums or roses which are all at the same growth stage. Obviouslyfor an orchid to bloom well, it needs an abundance of stored food and this can only be obtained

from light at the optimum level for the plant. The clear MH makes the leaves of many plants turn redfrom the light intensity. Sugar is also evident.SIZE OF LIGHT - One 1000W MH or Sodium light will illuminate a 10 ft X 10 ft area although thiscan go to 12 ft X 12 ft for less light demanding plants. The bulbs transmit more light sideways thandown (bulbs must be mounted vertically) so the growing area should be enclosed, the walls painteda flat white or covered with tin-foil or Foylon. Foylon is a strong coated cotton which can be easilystapled, cut or stitched. The MH light itself may be positioned safely above head height in the centreof the growing area. The ballast and capacitor should be mounted in an electrical box and may bepositioned up to 10 ft from the light. This means it can be outside the growing area if required. Theballast does give off heat which may be useful in a greenhouse. There are 400V flowing from ballastto bulb so the whole setup should be wired and grounded correctly. A 400W bulb can cover a 5 ft X5 ft growing area. It should be noted however, that the 1000W bulb gives off more than 2 1/2 timesthe light of the 400W so think big - go for the larger size and buy more plants! You will require

industrial-type time switches to operate the lights, the simple plug-in types mentioned in an earlierarticle will not do as they are only two-pin and don't have the current carrying capacity.


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This may all sound expensive, but you will get so much more useable light for your powerconsumption than with fluorescent tubes that it is worth the initial cost. The nicest thing is that theMH bulb is up out of the way and you can see, work on and water your plants without cumbersomefluorescent light units being in the way.In a greenhouse, the MH light can be mounted in a reflector to shine the light down to the plants.The whole unit can be left in place all year, even when not in use and won't be in the way. MH and

even fluorescent lights should not be switched on and off like ordinary light bulbs as this greatlyreduces their life. MH's must be allowed to cool off for 30 minutes before restarting as it is easier onthe bulb.I have found the MH light to be a wonderful grower of orchids. I have grown cattleyas, paphs,odonts, brassias, oncidiums, masdevallias, pleurothalids, etc. with success. The plants growstrongly all year just as, I am sure, they do in nature, near the equator where there are no shortwinter days.Peter Holmes


(by Peter Holmes)

Wrapping It All Up

My present setup is a 15 ft X 15 ft area in the basement which had not been used for anythingpreviously. It is completely enclosed and covered with Foylon to bench level. Two 1000W MH clearlights are mounted, 4 ft apart in the centre about 6" above head height. The ballast boxes aremounted outside the room as they produce too much heat. I have noted that the latest CGE ballastsare much quieter than the old ones.As the 2 bulbs give off a lot of heat, I have an extractor fan mounted in the outside wall at lampheight. Another fan blows air in at ankle height. Both fans are reversible and were obtained fromCanadian Tire for about $60 each.I use three fans to circulate the air around the room, these run 24 hours a day. There are twoinexpensive humidifiers to be used when required. The benches are mostly 42" high although asthere is a large rock in the room, some benches are higher. As the benches are this high, there is

room for two trolleys to be used in the open area to house shorter plants such as seedlings andmasdevallias. These trolleys can be pushed under the main benches if anyone wants to get into theroom!The closest plants are 2 ft from the bulbs. As the light from MH travels sideways, the reflected lightfrom the Foylon adds to that reaching the plants directly from the bulbs. A tiered bench arrangementwould be better but is rather impractical in this particular room.The plants are all in seedling flats, one with holes inside one without with spacers in between toallow water to drain better. Watering is accomplished by a submersible pump in a 14 gallon garbagecan (Rubber maid - won't split). I have to top up with warm water sometimes in the winter, otherwisethe water would chill the plants.My mix is moisture-retentive so I water about every 7 to 10 days with very dilute fertilizer - balanced20-20-20 or similar. I use a 6-6-6 fish fertilizer sometimes, it is believed that organic fertilizerscontain trace substances not found in 'chemical' fertilizers.

The lights are on 14 hours and are controlled by 2 time switches. In this manner, if it gets too warmin the summer, even with the fans going, I can have one light on for 7 hours, then the other one onfor the same time which keeps the heat down.It is essential not to let my cool growing plants dry out in the summer as they dessicate fast, hencethe need for a moisture-retentive mix containing perlite, some peat, styrofoam granules, pumice,charcoal and sometimes aquarium gravel. Some plants are mounted on tree fern and require dailyattention, whether they get it is another story!One result of the use of MH clear lights which are strong in blue light and perhaps a bit low in red, isthat the leaves of my plants are shorter than 'normal' but much harder and more resistant to fungalattacks. However, because of the consistent light level, it is essential to feed and water equallyconsistently for best results otherwise the plants do suffer and can get fungal problems.The light from MH 1000's is very strong so it is best not to look at them directly. When they are new,they give off a fair bit of UV light so I have found it easier on the eyes to use sunglasses if I am

going to be near them for long. As the lights age, they do become softer in color, then they are notso much of a problem.


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It is lovely on a dull, wet day in December, to enter the plant room and see all the odonts,masdevallias, etc. in bloom, basking in their tropical sun. Somehow then, all the hard work andexperimentation and the frustration seems worth it. It is even moregratifying to gain AOS awards onplants grown in an area which never receives anynatural light!I do hope this series of articles has inspired you to try growing indoors, to try orchids if you have not

already. You may find your own solutions to your own growing problems, but if you have gainedsome ideas from these articles then I am very pleased to have been of some help.Good luck!Peter Holmes

Catoctin Orchid Society

Newsletter Excerpts

Basement Orchid Culture Under Lights -- April 1995by John Burleson

The following article relates the decision, design, and implementation processes experienced by a new orchid

hobbyist faced with the often inevitable situation of having too many plants and not enough windowsills. Hissolution, as well as variations on the theme that have been implemented by other Catoctin Orchid Societymembers, provides an less expensive alternative to traditional greenhouse solutions.I've only been involved in the orchid growing hobby for ten months. In that time, our collection ofPhalaenopsis orchids has vastly exceeded what would fit onto any windowsill.

Not having time, winter quickly approaching, we decided to construct a temporary structure in our basement.After much thought, confusion and anxiety, we came up with what we felt would be a suitable design for our

plants.

First we framed up an 8 by 12 foot area using standard 2x4 studs. In one end we constructed an opening andinstalled a 36 inch wide storm door. We then covered the inside of the room with 6 mil plastic sheeting.For fresh air and cross ventilation, a standard variable speed bathroom exhaust fan was installed in the end ofthe structureopposite the storm door and ducted to the outside using dryer vent hose. By slightly opening the

window in the storm door, fresh air from the house could be drawn through and vented outside along with theincreased humidity acquired along the way. This also helps maintain a slight negative pressure in the room,which keeps the humidity out of your house. The throughput can be regulated by varying the speed of theexhaust fan.Air circulation within the room was achieved by installing a moisture resistant 42 inch ceiling fan in thecenter of the room. This would help to keep the air temperature and humidity evenly distributed among the

plants. This is especially important when growing under lights as dry areas are sure to develop.


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Waterproof benches were constructed using pressure treated lumber, fiberglass, and powder coated expandedmetal. After installation around the perimeter of the room, they were plumbed into a drainage system in orderto simplify the watering process.Humidity is provided by a Hermidifier 500 installed under one of the benches. It is quite capable ofmaintaining humidity levels as high as 90 percent regardless of the throughput created by the exhaust fan. Weare using a humidity level of approximately 80 percent, which is considered by some to be slightly high.

For lighting, we are using Metal Halide fixtures incorporating Osram and Tungsram, HQI technology lamps.Fixtures utilizing these lamps must be properly designed so as to properly ventilate the lamp and associatedcomponents, while protecting the user from ultraviolet radiation.This format was chosen because of it's extremely high output, energy efficiency, compact size, and largeselection of color temperature lamps to choose from for our experiments. We have had good results withlamps ranging from 4,000 to 6,000 degrees Kelvin.The most difficult aspect of this project was in applying the correct intensities. Since the majority of lightmeasuring instruments are sensitive only to a narrow band of the electromagnetic spectrum, around 550nanometers, the published values become inaccurate under artificial light. In fact, because of wave spectraldistribution variances, it will change from lamp type to lamp type.So far, we have only tested Phals and a few mini Catts under these lights and are impressed by the results. Theleaf color, flower quality, constant blooming and multiple spiking have been quite impressive.Please remember, I'm only a beginner sharing my experiences. I'm not a highly acclaimed expert on orchid

growing. I therefore recommend that you thoroughly research any ideas from this or any other article beforeincorporating them into your culture regime.

http://www.geocities.com:0080/RainForest/4112/burleson.htmlhttp://spray.egroups.com/message/orchidslovers/55


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Growing Orchids Under P. L. Lights (http://www.orchidweb.com/PLlite.htm)

Orchid plants have been grown under high pressure sodium lamps for many years. The recent development ofthe Phillips SonAgro bulb, which is 13% higher in the blue spectrum and 7% brighter, has made orchidculture under these lights even more rewarding, producing better growth and more frequent flowering.

It is important to remember that foot-candles as stated in books for growing orchids in greenhouses isgenerally measured at peak sun hours usually during noontime. This does not take into account low lightlevels received in the early morning or afternoon. Under sodium fixtures, light is constant throughout the dayand the additional hours of this constant light add up and provide adequate light to grow the plants properly.Much of the light that is critical to the plant, i.e., far red light, is not measurable in terms of foot-candles.Foot-candles are a measurement of light based on the equivalent of one candle at one foot distance from themeasuring device. This is based on visible light. Orchids growing under sodium light will actually grow underfewer foot-candles than orchids grown in daylight measurements.

The P.L. lights model best suited for orchid growing is the 430 watt model, utilizing the Phillips 430 wattSonAgro bulb. There are three different styles of reflectors: a wide angle reflector for low mounting situations(3-4 feet), a medium reflector for midrange mounting(5-7 feet), and a deep reflector for higher mounting (8-9

feet). The typical growing area one of these lights will cover is about 8' x 8' if lower light plants are placed onthe perimeter.

A key factor in determining the area that will be covered by these lights is the amount of reflective surfaces atthe perimeter. If these lights are mounted in a basement area at the 7-8 foot mounting height, and if none ofthe walls are reflective, the areas receiving adequate light will be reduced to 6' x 6'. Placing white plastic onthe ceiling and all sides of the room will increase the light level by as much as 30% and keep the humidity at ahigher level.

We recommend that if you are going to grow under lights in the basement, you place your growing area in acorner of the room or along one of the concrete walls. This will act as a heat sink and keep the temperaturesfrom going too far into the extreme. The walls should be painted with a vapor seal type paint to keep humidityfrom working its way out of the concrete block. (Humidity can cause chips of the block to freeze and pop

out.) It is recommended that either the outside of the block be covered with Styrofoam to a level about 1 footbelow ground, or the inside layer of the block be treated with vapor seal paint or covered in plastic.

Because humidity rises, another area of concern is where the wooden plate meets the concrete block aroundthe ceiling area of the basement. This area typically is colder and the warm humid air will rise and condenseagainst the plate and cause eventual rotting. We recommend that this area be insulated and sealed off with

plastic. 2" closed cell foam glued against the plate will protect it from moisture and keep the coldtemperatures out.

Constructing a Growing Area

An important thing to consider is the utility of the area. When you water your plants, where will the water go?

Will humidity damage anything? How can I reflect the light back into the plants where it is most needed?Again we recommend you cover the ceiling with white plastic, and either paint the walls white, or simplydrop a white plastic curtain from the ceiling to floor level.


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When it comes to water and drainage, there are many ways of getting around that problem. You can eithergrow your plants on humidity trays with water collecting underneath as you water the plants, or on bencheswith custom drip guards that drain into a large bucket or barrel that could be pumped out as needed. Ofcourse, the easiest solution is to build this area over a floor drain.

Temperature fluctuations will be regulated by:1. the average temperature in your basement2. the heat given off by the high pressure sodium light3. any heat or cooling vents in the room

These lights will give off 1200 BTU's an hour, and should raise an 8' x 8' room up to the high 70's to mid 80'sfor a daytime temperature. Night temperatures should fall to whatever the normal basement temperatures are.In the hot summer months, the basement is an excellent area, as it is cooler than the outside and the humidityis higher as well. Depending on the kind of plants you are growing, the ideal temperatures generally rangefrom 60-64 degree nights and 73-83 degree days.

We recommend an oscillating fan be mounted in the room to keep the air moving. This will help preventfungi, mold, and bacteria from developing on the plants. It will bring more oxygen and carbon dioxide past

the leaves for better growth.

If your temperatures run too warm in this area, we recommend that you simply open the door to the rest of thebasement, or install a reversing exhaust fan through a window to the outside that will exhaust the heat outfrom the basement during warm spells or bring in cool air from the outside at night.

These lights can be mounted to a track or to your floor joists utilizing 2 metric bolts that slide into a T-trackon the top of your light fixture. These bolts are secured by utilizing simple pipe strap as you would find at thehardware store. Screw the pipe strap into the floor joists on either side and run the metric bolt through one ofthe perforated holes in the pipe strap. If preferred, you can order track which can be mounted to the joists andthe light can be mounted to the track utilizing track clips. The track comes in lengths up to 20' and can be usedwith U-track joints, extending the track as long as necessary.

We recommend you consider the size of the room that you wish to build, and remember that usually orchidcollections tend to grow both in plant size and number of plants. Plan a size 1&1/3 to 2 times the size youthink you need. Allow yourself the ability to expand from the beginning. One light will cover 8' x' 8' area, andtwo lights will cover approximately 10' x 12' area. Spaces larger than that we run through the computer todetermine mounting height and distance between lights and walls in order to calculate adequate illumination.Most light setups with P.L. lights operate at 400-500 foot-candles. This is adequate for most plants to grow

properly. Plants requiring higher light can be placed in the center of the growing area or up on tiers closer tothe lights from 3' -5' away. Low to medium light plants can be placed at the perimeters.

Benching

Tiered, wire mesh benches can be purchased through different suppliers. You can also make your own out of

redwood, cedar, or treated wood. Use a 2 x 4 frame with a plywood bottom lined with plastic and filled withlava rock as an extra humidifier. When constructing this bench we recommend you install a valve to allowdrainage of excess water and to allow cleaning and flushing out every so often. Above this frame you shouldinstall either 2' x 4' plastic lighting grids as used for fluorescent lighting, or a wire bench mesh. You can alsosimply use 1" x 2" slats spaced 1" apart to allow adequate drainage and support for your plants.

Remember that when building your bench, the human reach is about 3', so don't build your benches any wider.2-3' is an excellent size. A 6' wide bench in the center can be reached from both sides. Consider the movementyou will be making in this area and lay it out accordingly. Custom rolling benches are available for largergrowing setups.

Utilizing High Pressure Sodium Fixtures in the Hobby Greenhouse

P.L. Lights High Pressure Sodium Fixtures are an excellent source of light to extend winter daylight hours


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and provide light during periods of heavy cloud cover. Growth continues uninterrupted and flowering is fasterwith higher bud count.

The fixture draws 450 watts total or 4.2 amps at 120 volts, 2.2 amps at 240 volts. They are available in threereflector styles: wide angle, medium, and deep. All can be wired with cord for 120 volts or 240 volts.

Light with medium reflector, no cord or plug.....................$245.00Light with medium reflector, wired with cord and plug.....$255.00Light with deep OR wide reflector, no cord or plug..........$250.00Light with deep OR wide reflector, wired w/ cord & plug.$260.00Replacement bulbs................................................ ...............$40.00Shipping charges anywhere in the continental U.S............$25.00Picked up at our greenhouse, shipping charge..................$15.00

For Alaska and Hawaii, we will provide shipping quotes.These lights, available in all voltages and phases, can be shipped to any destination in the world. Foreigncustomers will be responsible for customs fees. Any questions on these systems, be sure to call or write.Orchids Limited will be glad to work with you in developing your growing area. Simple growing setups thattake no longer than 15 minutes to discuss over the phone will be provided at no extra charge. More complex

operations are billed at a consultation fee of $90.00/hour for hobbyists.

House Plants - Artificial LightAdapted from Agdex 285/20-8.

Light is needed by a plant for using nutrients and manufacturing food. It has a great influence on chlorophyllproduction, growth rate, leaf size, and flower and seed production. One of the common problems encountered

by the indoor gardener is poor light availability, particularly in apartments with limited window space orduring winter when light intensity is low. Artificial lights are useful when natural window light is insufficient.They make it possible to grow healthy plants in any spot in the home: bookshelves, a heated garage, an emptycloset or even an attic. The use of lamps encourages compact, luxuriant growth and regular blooming.As a supplementary light source, even a small portable reading lamp will improve plant health. It can beturned on for one or two hours at dawn and dusk to increase day length, especially in winter. Plants growingin a dim corner will visibly improve if they receive four to six hours of artificial illumination from anoverhead light.Only when a plant's entire fight requirements are being met by artificial sources must special lighting

provisions be made. Plants absorb red and blue light, both are used to control photosynthesis and variousaspects of plant growth. Red fight (6000 to 7000 angstroms) mainly controls maturation, and flower and seed

production; it is particularly important to flowering plants. Used alone, red light will make plants grow talland spindly. Blue light (4000 to 5000 angstroms) chiefly controls leaf development; plants grown under blue

light alone tend to be short and stocky, with thick stems, dark green leaves and few flowers. Ultraviolet raysare used only in small quantities and can easily damage plants.Incandescent lights (the round bulbs normally used in the home) can supplement natural daylight for foliage

plants with low light requirements, but they do not provide enough light to meet and needs of floweringplants. They give off a large amount of red light and infrared radiation, most of which becomes heat. Thiscauses cooling problems and burning of leaves. Because the fight source is concentrated in a small area, lightdistribution is likewise restricted to a small area.Fluorescent lights have a higher light efficiency than incandescent lights. emitting two and a half times asmuch light per watt. Fluorescent tubes vary in red-blue output. A combination of cool white and warm whiteis recommended for use on house plants.Most house plants can be grown under fluorescent lamps alone, although it is a common practice to mixincandescent and fluorescent light in the ratio of two or three florescent lamp watts to one incandescent lampwatt. This provides the proper light quality without excessive heat. Daylight, warm white, and natural white

tubes can also be combined in various ratios to provide a suitable quality for plant growth. Gro-Lux, Plant-Gro and other brands of agricultural fluorescent lamps are specially designed to provide a balance of red and


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blue light suited for plant growth. However, it is the quantity and brightness of light that is most important,not the quality of the light. A reflector, such as a mirror or white sheet of paper placed under the plants, willimprove efficiency by reflecting light back onto plants.As a rough guide, tubes should be arranged to provide approximately 175 to 225 watts of light per squaremetre of growing space. Lights are usually placed 30 to 45 cm above the tops of the plants. However sincedistance from a light source directly affects light intensity, this will vary according to individual plant

requirements. If a large area is to be illuminated, it is better to use one long tube rather than two short tubesplaced end to end; this avoids a dark spot in the centre, because intensity decreases near the ends of the tubes.Lights should be kept clean for maximum brightness, and discarded as they wear out (after about one year).Commercial light systems are now available at varying cost. They usually include a reflector, a trolley withadjustable shelves, two 40-watt fluorescent lamps, and sometimes one 25-watt incandescent bulb. These can

be connected to regular electrical outlets in most cases. These special units are not necessary. Lamps can bepurchased alone and fitted into the design of your home, as long as they provide sufficient fight intensity. A photometric light meter will help to determine correct placement of plants in relation to fight sources.Automatic timers are also available; they can be connected them to the lights to switch them on and off atregular intervals.The intensity and duration of illumination required vary from plant to plant. Older, mature plants need lesslight than young, active ones; flowering plants have high light requirements 6000 to 10,000 lux most foliage

plants need from 1000 to 6000 lux; variegated and colored foliage plants need more; for root cuttings, 1000 to

2000 lux is sufficient; flowering bulbs need 500 to 1000 lux.Experimentation is the only sure method to determine the best solution for each plant. If plants are notreceiving enough light, they begin to grow tall and spindly as if stretching towards the light, and foliage

becomes pale green. Such plants should be placed nearer the light source, or given a longer exposure period.If too much light is problem, bleaching of leaf and flower color occurs, and may lead to browning andshrivelling. Leaves are small and overly compact, and may curl under at the edges. Too much light inhibitsflowering in species such as poinsettias, orchids and chrysanthemums. Most plants thrive with 14 to 18 hoursof light per day when placed 30 to 40 cm below the lamps. Adjustments should be made according toindividual requirements.Growing habits of many plants are directly affected by day length; this phenomenon is know as photo-

periodism. Some plants will not flower unless exposed to 12 to 14 hours of light each day for a certainnumber of days. These are known as long day plants and include calceolaris, many garden annual and

begonias. Short day plants must have more than 12 hours of complete darkness each night to allow bud

development; kalanchoe, poinsettia and chrysanthemum are examples. A third group is termed indifferent;they will flower as long as they receive sufficient light. This group includes African violets, tomatoes andimpatiens. The light intensity required to trigger photoperiodic responses in plants is very low and in somecases less than 10 footcandles.Care for plants grown under artificial light is the same as for regular house plants. Your success depends onthe attention you give them. Proper growing media, temperature, humidity and ventilation must be provided.Watering and fertilizing schedules may require stepping up to keep pace with the steady, active growthencouraged by increased light. It is important to remember that plants don't receive natural rest kept underconstant light. After flowering, most plants should be placed in a moderately-lit area, and given less water andno fertilizer to encourage dormancy. Apart from this, experience is your best guide.

Last Revised/Reviewed August 27, 1996

http://www.agric.gov.ab.ca/crops/hort/houseplants/lights.html

++++++++++

Indoor cultivation

a ) Hobbyist

1. Natural light. - The climatic conditions may mean that the plants you wish to grow cannot be grown easilyoutdoors without protection. A windbreak or courtyard may be required for wind shelter. More severeenvironmental conditions may require a cover over the enclosed area. Glass provides the best lighttransmission and also the best heat gain or loss. Do not use green fibreglass for a roof covering as this willinhibit plant growth. Try to control large fluctuations in temperature and humidity and remember that good

ventilation is essential for plant growth.
http://www.agric.gov.ab.ca/crops/hort/houseplants/lights.htmlhttp://www.agric.gov.ab.ca/crops/hort/houseplants/lights.html


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2. Fluorescent lighting. - works OK with cool white but try for the gro-lux, tri-phosphor or tru-lite tubes. Tobe effective fluorescent lighting has to be very close to the plant leaves because the light energy from artificiallight drops off very quickly as the distance from the light source increases. Some plants that have low lightrequirement can be grown successfully under fluorescent lighting. Seedlings and cuttings can be grown andraised using fluorescent lighting.

3. Incandescent lights produce more heat than light suitable for most plants so are generally not used. Thereare some gro-light bulbs that are available which have a blue coating on the globe.

4. Mercury vapour lights have been popular with those people who can buy factory demolition materials.Mercury vapour lights in factories are usually called hi-bays and have a parabolic reflector to provide evenlight at about five metres away ( 16 feet ). Some people have replaced the reflectors and grown plants usingthese lights but have had to breed plants that can use the low light temperature. The mercury vapour hi-baysgenerally have the light fitting attached to the control box. If a suitable ignitor is fitted inside the control boxof a 400 watt hi-bay then it can be used for normal 400 watt metal halide lamps. There are retrofit metalhalide globes that can be used with unmodified hi-bay 400 watt mercury vapour control equipment but theseglobes are nearly twice the price of a normal metal halide globe.

5. High Pressure Sodium and SON-T type lights have been used to extend the daylight hours in the winter and

spring in countries like Holland. These lights are becoming popular with indoor hobbyists. These sodium typelights tend to produce light at the red/yellow end of the light spectrum and some plants can " stretch " and

become " stalky " when these lights are used exclusively for growing plants indoors.

6. Metal Halide lamps are probably the most efficient to use indoors because they provide the type of highenergy light source which most plants require for growth. The hobby indoor gardener will tend to use either a400 watt version or a 1000 watt version.

Depending upon the plants to be grown as a very rough rule of thumb a 400 watt metal halide lamp with achina hat type reflector will provide enough light for a growing area 120 cm x 120 cm ( 4 foot x 4 foot ) A1000 watt metal halide lamp with a china hat type reflector will provide a growiing area 150 cm x 150 cm ( 5foot x 5 foot )

The light from the high performance lights contains rays that can cause eye problems similar to the effects of" welding flash " and " snow blindness " When in a growroom wear safety and protective eyeware.

High pressure sodium ( HPS ) and metal halide ( MH ) lighting systems are high performance units and because of the control mechanisms when switched on they draw an inductive current which can causeproblems with normal domestic timers and electrical circuits. Before buying or using any type of indoorlighting get professional electrical advice to make sure that what you plan to use is safe for your particularsituation. REMEMBER THAT ELECTRICITY WATER AND HUMANS CONNECTED TOGETHER IS AFATAL COMBINATION. ( The other consideration is that in the event of an insurance claim if the lights ortheir installation or operation was not disclosed to your insurance company then any claims on your insurance

policy may be denied before setting up growing lights indoors check your insurance policy ).

b) Commercial indoor cultivation.

--------------------------------

If the commercial grower has to provide a structure in order to grow plants then the capital cost of thestructure and its running costs must be paid for by the increased price the grower can obtain for the end

produce. It may be that the grower cultivating indoors or under cover may be able to supply plants when noneare available locally or the grower may be able to sell his plants before the same plants grown outdoors areready.

The cost of providing artificial lighting as well as a structure means that the financial and marketingconsiderations have to be correct otherwise the grower goes broke very quickly.

As soon as you start to grow plants inside a structure the following areas have to be considered.

Light controlHeat control


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Humidity controlAir movementPest and disease controlPollination ( for flowering and fruiting plants )Cultivation and harvesting systems

Nutrient and water systems

The notes on this page are to give you a quick summary of some of matters to consider if you intend to growplants indoors or under some sort of covering.http://www.olis.net.au/soladome/indoor.html

LIGHTMost plants, including orchids, require light to perform photosynthesis. There are many kindsof orchids and each has a different lighting requirement due to where they live in their naturalhabitat. Some are exposed to a bright tropical sun while others live deep within shady forests.You need to learn what types of orchids you have and try to provide them with the samelighting levels they would normally receive in nature.

Light is measured in a unit called a footcandle (fc). A footcandle is equivalent amount of lightthat is produced by a candle at the distance of one foot. To give you an idea of light levels, ona clear sunny summer day at noon, the light in the sun would be over 10,000 fc. At the sametime of day on a overcast winter day, the light level may be less than 500 fc.You most likely will not be able to tell the true light level in an area because the human eye istoo efficient at adjusting your vision to a broad range of light levels and can be fooled by thetype of light present. For example, a grocery store may appear brightly illuminated withflorescent lights, but in reality, the light level may be as little as 500 fc. To determine the lightlevel in the location you want to grow your orchids, you will need a light meter that will giveyou readings in footcandle units and is capable of measuring bright light up to at least 5,000footcandles. You can also determine the light levels at a location by using the built-in lightmeter of a SLR-type camera using a special table:

SLR CAMERA LIGHT MEASURING TABLE

IF you do not have a light meter or any other way of measuring light levels, here is a veryrough rule of thumb you might follow:

Full Sun: Direct sunlight that's unobstructed for six to eight hours a day.

Partial Sun: About four hours of direct sun a day or lightly shaded sunlight all day.

Partial Shade: About two hours or less of sunlight a day.

Filtered Sun orBroken Shade:

No direct sun, but some filtered light.

Dense Shade: No direct sun at all.

- - TOO LITTLE LIGHT - -

How do I know if I am not getting enough light?If your orchid is showing any of these signs, chances are it is not getting enough light.

1. Dark green leaves with no luster to them. The roots system is fine.
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2. Each new growth is smaller than the last growth.3. Your orchid is floppy and very weak looking.4. It has not bloomed or it has very few blooms.

How can I increase my light?You need to move your orchids into a better light source, a different window, open thecurtains, remove objects that maybe shading the window such as a tree or awning.

Be very careful when introducing you orchid (or any plant, for that matter) to more lightbecause a plant that has been in poor light for any length of time will have very delicateleaves that can burn easily. Move your plant to a higher light level gradually over severaldays. If you notice the plant leaves burning (they will turn brown and be very dry), move theplant further away from the light source or provide some shading for a week or two until theplant gets used to the increased light.If you are growing your orchids under electric lights:

1. Reduce the distance between the light and the plant.NOTE: If you are using incandescent lamps, be careful not to place the plants tooclose to the hot light.

2. Move the plant toward the center of the light.3. You should operate your lights 14 to 16 hours a day.4. Make sure the bulbs are not over a year old, older bulbs tend to give out less light.

5. Use a special "grow light" in your fixture.

- - TOO MUCH LIGHT - -How do I know if I am getting to much light?

There are several ways you can tell if your orchid is getting too much light:1. The leaves are showing burn spots. The spots can be yellow or brown dry patches

on the leaves. They could also be rough and slightly raised.2. The leaves feel hot to the touch. Leaves should be cool to the touch.3. The leaves start turning black and dropping off. A plant exposed to too much

sunlight will eventually die.4. The plant's growth is stunted and the leaves start to turn yellow.5. On some orchids, the color is bleached out of the leaves.

How can I reduce the amount of light?This is easier to control than not enough light.

1. Move the plant away from the hot sun. Remember that the sun coming thru awindow and maybe intensified by the glass.

2. Afternoon sun is also much "hotter" (brighter) than the morning sun, so move theplant to a East-facing window.

3. Place shear curtains in front of the windows.4. Provide shade if growing out doors. A plant that may be fine in the spring but could

get burned as the sun moves higher in the sky toward summer.If you are growing under lights, you usually don't run into this problem unless you leaveyour lights on all the time or the lights are too close to the plants.

Typical lighting requirements for the most commonly sold orchids:

Phalaenopsis1000-1500fc

Never exposed to direct sun light.

Paphiopedilums1000-3000fc

Expose to only early morning sun.

Miltonia1000-3000fc

Keep in diffused light.

Odontoglossums1500-2000

fc

Expose only to morning or evening sun.

Cattleyas1500-3500fc

Give plenty of light without burning their leaves.
http://www.orchidlady.com/dict-p.html#PHALAENOPSIShttp://www.orchidlady.com/dict-p.html#PAPHIOPEDILUMhttp://www.orchidlady.com/dict-m.html#MILTONIAhttp://www.orchidlady.com/dict-o.html#ODONTOGLOSSUMhttp://www.orchidlady.com/dict-c.html#CATTLEYAhttp://www.orchidlady.com/dict-p.html#PHALAENOPSIShttp://www.orchidlady.com/dict-p.html#PAPHIOPEDILUMhttp://www.orchidlady.com/dict-m.html#MILTONIAhttp://www.orchidlady.com/dict-o.html#ODONTOGLOSSUMhttp://www.orchidlady.com/dict-c.html#CATTLEYA


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Vanda1500-4000fc

They like strong light, full morning sun.

Oncidiums1500-4000fc

Same as above.

Dendrobiums1500-4000fc

Same as above.

Cymbidiums7000-8000fc

Give as much light as possible without burning theleaves. Provide lower light (2000-3000 fc) when flowerspike appears.

NOTE: there are species in these genera that may require different light levels.

How to measure your lighting level using a SLR camera(table data reproduced by permission from Jochim SaulHTML by Greg Brother)

f-stop

f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22

EX

P

O

S

U

R

E

T

I

M

1/4 0.5 1 2 4 8 16 32 64 1251/8 1 2 4 8 16 32 64 125 250

1/15 2 4 8 16 32 64 125 250 500

1/30 4 8 16 32 64 125 250 500 1000

1/60 8 16 32 64 125 250 500 1000 2000

1/125 16 32 64 125 250 500 1000 2000 4000

1/250 32 64 125 250 500 1000 2000 4000 8000

1/500 64 125 250 500 1000 2000 4000 8000 16000

1/1000 125 250 500 1000 2000 4000 8000 16000 32000

1/2000 250 500 1000 2000 4000 8000 16000 32000 64000

Light Intensity in Footcandles (fc)

~~ INSTRUCTIONS ~~1. Set the film speed of your camera to 100 ASA/ISO.2. Place a sheet of white paper in the location where you want to perform the measurement.

Position the paper so it will receive highest light intensity possible.

3. Point your camera to the paper and get close enough to it so that the

white paper fills the entire view finder. NOTE: You don't need to focus your camera.

4. Read the f-stop/exposure time values on your camera.5. Using the table above, find the corresponding light intensity in footcandles.

For example:

If the f-stop is f/11 and you get an exposure time of1/125 sec, this would mean there is a light

intensity of about 1000 fc.

Typical Lighting Requirements For OrchidsBrassavola 2000-4000 fc Masdevallia 1000-2500 fc

Brassia 2000-3500 fc Miltonia 1000-3000 fc

Cattleyas 1500-3500 fc Oncidiums 1500-2000 fc

Cymbidiums 7000-8000 fc Odontoglossums 1500-2000 fc

Cymbidiums in bloom 1500-3000 fc Paphiopedilums 1000-3000 fc

Dendrobiums 1500-4000 fc Phalaenopsis 1000-1500 fc

Epidendrum 1500-3500 fc Phragmipedium 2500-3500 fc

Laelia 2000-3500 fc Sophronitis 1500-3500 fc

Ludisia 1000-2000 fc Vanda 1500-4000 fc
http://www.orchidlady.com/dict-v.html#VANDAhttp://www.orchidlady.com/dict-o.html#ONCIDIUMhttp://www.orchidlady.com/dict-d.html#DENDROBIUMhttp://www.orchidlady.com/dict-c.html#CYMBIDIUMmailto:[email protected]:[email protected]:[email protected]://www.orchidlady.com/dict-v.html#VANDAhttp://www.orchidlady.com/dict-o.html#ONCIDIUMhttp://www.orchidlady.com/dict-d.html#DENDROBIUMhttp://www.orchidlady.com/dict-c.html#CYMBIDIUMmailto:[email protected]:[email protected]


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