Asian Cymbidium Orchids, traditional Chinese, Korean and Japanese Orchid Containers

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Controlled Growing Conditions (Continued)

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Cymbidium sinense (left), compared to the named clones Ta Ming (center) and Dou Mo (right)

Temperature

Generally, the ideal cultivation temperature for Cymbidiums is 20-30C. With a 10C drop between the day and night temperature. However, different species will grow optimally at different temperatures. For example, faberi and gorengi, found in nature at the higher altitudes, prefer temperatures of 15-25C, and can withstand winter temperature close to freezing. Summer temperatures over 30C will hinder their growth, and ability to flower. On the other hand, sinense, which is found at lower elevations, cannot withstand extended periods of temperature below 5 C without suffering some reduction in growth, but are tolerant of higher summer temperatures (over 30C) as long as they are accompanied by high humidity. The reduction of growth caused by high summer temperatures is manifested in either stunted spikes no flowering during the following season. When growing in climates where summer temperatures can approach 30 C one must increase the air circulation and use automatic misting or evaporative cooling to increase humidity and keep the temperature down.

Humidity

There are two distinct periods for both watering and humidity control. During the winter rest months, October to March, the humidity can be controlled to 40 - 60%. During the growth season, between April to September, the humidity should be maintained at over 80%, while maintaining good air circulation. Indoor growers can boost the humidity by using water trays underneath the plants. These trays can be filled with pea gravel to keep the water from touching the plant roots while creating a suitable microclimate for the plant. Outdoor growers, using a lathe house for shade, may prefer sprinkling in the mornings coupled with misting throughout the day to raise the humidity around the plants. When using this method caution is advised during the new growth period. Water can collect in the center of the new growth and cause crown rot. This will kill the new growth.

Ventilation

Asian Cymbidium species all like good ventilation. Poor ventilation will encourage plant diseases, insect infestation, and encourage mold and rapid breakdown of the growing media. Oscillating fans, large box fans and high volume exhaust fans can all be used. In my greenhouse, I have several tiered shelves of plants. The shelves have holes in them so that the Asian Cymbidium vases hang below the shelf, and the plant is above. This arrangement requires extra ventilation. I keep the box fans and reciprocating fans running constantly for general air circulation. The exhaust fans and automatic roof vents are on temperature control. If the greenhouse is overheating, the exhaust fans will draw in outside air to cool the greenhouse. I also use two misting systems, one on humidity control, and the other that comes on automatically in conjunction with the exhaust fan to cool, and replace the humidity lost in the exhaust.

This two-part article appeared in the American Orchid Society Magazine "Orchids" in July 1999 and August 1999. All photographs are copyright of Charles Marden Fitch 1999 and cannot be used without permission of him or the author.