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Growing Better with More Light Fred Bergman
A search of the literature produced a list of possible factors that could improve my Phalaenopsis culture . The list included light , mix , temperature , humidity , and fertilization . Because of prior experience I decided to continue to use a peat-based mix with the high and low temperatures dictated by utility costs . Fertilization would remain unchanged at the rate of 200 ppm of nitrogen . I planned to add shading only as required to limit greenhouse temperature . Remaining was the single question : would plants benefit from an increase in light ? These studies used a definition of minimum light as the amount of light just sufficient to produce flowers . Maximum light is defined as the amount of light Phals could beneficially use . What I found was increased light produced plants faster that were bigger and had more growths and blooms . In addition , Phals receiving high levels of light produce multiple side shoots and keikis . Limited tissue analysis indicated increased fertilizer utilization . As light was increased it became obvious that there was a need to increase humidity , air movement , and frequency of watering . Failure to increase these caused plants to suffer from dehydration and associated burning . Remaining is the question : does the literature describe the minimum light required or what can be profitably used ? Cur- rently I grow Asocenda , Phragmipedium , Paphiopedilum , Phalaenopsis , Lycaste and Cattleya ; all receive the same light and bloom freely .
What can be done to increase the amount of light ? In greenhouses , the light intensity can be maximized by installing a good cooling system . One common system uses fans to remove hot air replacing it with cooler air from pads moistened with water . Many hobby greenhouses lack a cooling system or have systems that are far too small . You can properly size an evaporative system by first calculating the volume of your greenhouse and dividing by 2 . This equals the required fan size . Divide the fan size by 30 to find the area of wet pad for a pad air exit velocity of 30 lineal feet ( 9.8 meters ) per minute . This system will allow you to increase your light until plants start to feel warm to the touch . The cost of operation is minimized by using a high-efficiency fan . Obtain a fan that removes sufficient air operating at 1.25 mm differential pressure .
Increasing the humidity will assist when increasing your light . Under-bench mist systems installed with spray heads about every 4-6 feet ( 1-2 m ) should be pulsed to produce the highest humidity . Pulsing increases humidity , while a continuous spray can actually dehumidify . My sprays are on and off 50 % of the time .
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Under light Phalaenopsis culture
2011 Third Quarter , Vol . 21 ( 1 ) - Phalaenopsis