Orchid Winter Temperature Management Methods and Precautions

There are many species of Chinese orchids, and their cold tolerance varies; they will not suffer frost damage above 0°C. For growing orchids in the Yangtze River basin, overwintering only requires placing the orchids under a south-facing corridor that is sheltered from the wind; when there is wind, snow, or severe cold, they can be temporarily brought indoors, and moved out again as soon as the weather clears. For growing orchids over winter in the southern provinces, because the frost-free period is long and winter temperatures do not drop to 0°C, there is no concern about freezing. In the north, the overwintering period for orchids is long, but every household has heating facilities, so the orchids can simply be brought indoors. The key is not how to prevent freezing but how to prevent stuffiness. Orchid-growing practice shows that in winter, orchids often die nine times out of ten from stuffiness and one time out of ten from freezing. Reasonably heating orchids in winter is not aimed at preventing freezing, but at extending the vegetative growth period. Chinese orchids usually enter vegetative growth at a temperature of 15°C, together with sufficient light and suitable humidity. This growth condition only needs 6 to 8 hours per day. Winter heating can reasonably be divided into two periods for comparison.

In winter, if the weather is clear and fine, the temperature in the orchid house can exceed 15°C; only when the weather is cloudy, rainy, windy, or snowy does the room temperature drop, and at this time heating and supplemental lighting should be used to keep the room temperature at 15°C. No heating is needed at night; maintaining 5°C is sufficient. Heating can be carried out in late autumn and early winter, with the purpose of promoting the full maturity of the current year's new plants. However, from after mid-December to the end of January, heating is not necessary; keeping the room temperature no lower than 5°C is sufficient, allowing its vegetative growth to remain in a very slow state. Starting from February, increase humidity, add heat, and provide sufficient light to bring the orchids into the growth period ahead of time. After heating, new buds sprout early; generally, after 45 days of heating, new buds emerge from the soil. After another 90 days, they can become mature plants. By mid-June, the second batch of new buds emerges from the soil again, thereby achieving the effect of growing two batches of new seedlings in one year. When heating in winter, note that lighting must be added, but never heat continuously for 24 hours in a way that results in no temperature difference. In addition, heating should not be too high; exceeding 25°C is harmful rather than beneficial.