Air humidity and Orchid cultivation in Northern families

Chinese orchids are required to grow in high air humidity, which is a genetic characteristic formed by long-term elimination selection in nature. many experts, scholars and orchid experts have studied, explored and summarized the relatively high air humidity needed by orchids. The complete Book of Chinese Orchids edited by Chen Xinqi (China Forestry Publishing House, 1998 edition, P260) points out that "the humidity of cultivated orchids should not be less than 70% in summer and 90% for special species of orchids." but the winter dormancy period can be reduced to 50%. Mr. Wu Yingxiang believes that Chinese orchids "in the growing period, the air relative humidity should be 60%, 70%, dormant period can be lower, about 50%." (Chinese Orchid, China Forestry Publishing House, 1991, P68) Mr. Xu Dongsheng examined that "the orchid originates from the valley forest, has a good natural shade, and is dry but not dry. the relative humidity of the air is 50% 55% in winter, 75% in spring, 65% in summer and 75% in summer and autumn. Therefore, artificial cultivation of orchid plants should meet their air relative humidity requirements as far as possible, generally speaking, the dormant period should not be less than 50%, and the growing period should not be less than 70% 80%." (Chinese Orchid cultivation and appreciation, Golden Shield Press, 2002, P26); Li Shaoqiu and Hu Songhua pointed out in Chinese Orchid (Guangdong Science and Technology Press, 1995 edition P87) that "humidity should be maintained at more than 80% during the April-September growing period for Lanhui, and it can also be reduced to 50% in winter." Yang Nianci believes that (common flower cultivation and appreciation, Shandong Science and Technology Press, 1982, P254) "the environment with high air humidity is beneficial to the growth of orchids, and it is appropriate to maintain 60%, 70%, 70% humidity." Li Renyun pointed out in "Lan Yun" (Anhui Science and Technology Press, 1999 edition, P21), "the relative humidity needed during the growing period should not be less than 70%, and the winter dormant period should be 50%." The textbook "Florology" (China Forestry Press, 1988 edition, P585), compiled by the Flower Teaching and Research Group of the Garden and Forestry Department of Beijing Forestry University, holds that "ground orchids require moisture in both air and soil, and summer is the growing season. In addition to keeping the soil moist, keep the air humidity at 45% by spraying water or spray at 65%." Ji Junzhao and Huang Lingyan said in the handout on Flower cultivation (China Forestry Publishing House, 1985 edition, P315) that "orchids install fogging machines in summer to maintain more than 90% air humidity."

The above are some influential orchid experts, scholars and orchid experts who have studied and summarized the relative humidity requirements of orchids from different angles. most of them think that 60% of relative humidity is needed during the growing period. A few documents think that 80%-90%, and some individual pages propose that 45% can also grow well. obviously, the data are not completely consistent, which makes it difficult for growers to refer to planting. As an orchid farmer in the north, he very much hopes that the humidity needed for orchid growth is lower, so it is easier to solve the problem for northern families to raise orchids. It is indeed necessary to continue to carry out more in-depth research to find out a more scientific and reasonable humidity index for orchids growing in hot climate areas in the north. It is an indisputable fact that orchids grow better under higher air humidity, but whether orchids cannot grow at a lower level, northern orchids must consider solving. Although Beijing is not too cold compared with northeast winter, it is dry and hot in spring and summer. The following table shows the average temperature and humidity in Beijing over the past 20 years. And the relative humidity has another characteristic, that is, it is very low during the day and rises at night, so the average relative humidity does not seem to be low. The following table shows the daily minimum and night maximum relative humidity recorded by me in Beijing in May, June and July 2003. It can be seen that although the average humidity is not necessarily very low, the humidity is below 50% most of the time during orchid photosynthesis during the day, which is disadvantageous to the normal growth and development of orchids. The dry and hot climate in spring and summer in Beijing is very different from the cool and humid climatic conditions of orchids, especially family orchids, because large-scale cultivation can be cultivated in facilities. for example, greenhouse or flower cellar can be built to control temperature, humidity and light to meet or approach the environmental requirements of orchid growth by spraying, ventilation and shading, but it is not easy for families to do so. Because the places where families raise orchids are connected with or are part of the bedroom, it is impossible to maintain a humidity of more than 60% for a long time. However, there are indeed a group of successful family orchids in Beijing who attach great importance to meeting the higher air humidity of orchids, and the methods adopted to solve the humidity problem are also different:

1. Spray water

Foliar and basin water spraying is a regular operation of family orchid cultivation, its purpose is to clean the leaf surface, and the other is to increase humidity. The effect of the former is obvious, and the unclean matter on the leaf surface can be removed more easily after spraying water. Humidification can also be achieved immediately, but the time effect on the increase of air relative humidity near the orchid basin is limited. Table 3 is the result of my actual measurement. Water spraying can immediately increase the local air relative humidity and decrease the temperature, but the maintenance time is not long. After spraying water, the increase in humidity of 40km / 60' is no longer obvious, and basically returns to the level before spraying. In order to maintain a high humidity for a long time, it is necessary to keep spraying water, which will lead to other problems, such as carelessness in the water of new buds can easily lead to "rotten bud core" (some data think so). At the same time, spraying too much water will cause the basin to be too wet, and it will cause the salt in the basin to move adversely with the spraying of water.

2. Increase the water area of orchid cultivation sites

The general and simpler method is to spread water-absorbing articles (such as old carpets, sponges, hemp bags and fine sand) on the floor or walls of orchid-raising places, sprinkle water on them, and often keep them moist. The effect of this method is remarkable and lasting, but not every family can do it, especially the small balcony or orchid places connected with the bedroom are sometimes not easy to control. Another method is to set up a water plate under the orchid basin, in which the supports (such as red bricks, wood strips, etc.) are added with water, and the orchid pots are placed on the supports, so that the water can be easily controlled. This year, the author tests and compares the temperature and humidity of different places (outdoor shade shed, indoor balcony, indoor balcony water plate and small greenhouse in balcony):

The above table can see several points. First of all, the air humidity of the orchid basin put on the water plate is significantly higher than that without the water plate, and it is higher than the other two groups during the day, the humidification effect is lasting, and the temperature is lower than that without the water plate (but the humidity is lower than that in the small greenhouse in the balcony). Secondly, the change range of temperature and humidity under the outdoor shade net is larger than that in the balcony, the temperature difference is 13.5 ℃, and the humidity difference is more than 60%, while the change of temperature and humidity in the balcony is relatively stable, so before the rainy season comes, the orchid pot is more advantageous to be put indoors than outside, but pay attention to ventilation and move to the outside again in the rainy season. Although I have not tested the effect of sprinkling water on the ground and wall absorbers to regulate humidity, it can be estimated that as long as the evaporation area is no worse than the water plate at the bottom of the basin. The area of the water plate tested above is about 0.6 inches. If the water area is increased, the effect of microclimate improvement will be good.

3. Family "facilities" to raise orchids

The so-called "facilities" actually refer to some equipment and measures adopted by northern families to raise orchids in order to create a microclimate suitable for orchid growth. the simplest "facility" is to add a transparent plastic cover to the orchid pot. in addition to watering and other management to open the cover is basically no longer open until flowering and orchid appreciation. This method is not only related to the Orchid Journal (Chinese Orchid 2000 5p13). In addition to the introduction of "Orchid", I have tried it, and orchid farmers in Beijing and Tianjin have also adopted this method. Although this is contrary to the traditional orchid ventilation, it is the most simple and effective way to increase air humidity, and there is no way, because northern orchid farmers think that it is more important to increase air humidity in the north ("Chinese Orchid", 20005p13). The use of this "facility" has indeed achieved good results. As for how to unify the traditional "ventilation" and the "humidity" emphasized in the north, it remains to be further explored.

Another kind of "facility" is to surround a relatively closed space with plastic or glass, the area depends on the conditions, commonly known as a small greenhouse, I seal a small greenhouse with aluminum alloy and glass in the balcony, the effect is very good from the moisturizing point of view, the measured data are as shown in Table 4 above. Judging from the actual situation of orchid cultivation, the advantage of this facility in the driest and hottest months in Beijing (orchids begin to grow) can first maintain moisture, and in addition, the temperature can be adjusted. When the temperature is low in early spring, the temperature in the small greenhouse is higher than that outside, and when the temperature outside is high, the temperature in the small greenhouse is lower than outside, which is conducive to the early germination and growth of orchid seedlings. But there are also deficiencies, after late June, pay attention to ventilation, I use a fan, at the same time, combined with the switch of the door of the small greenhouse to control the temperature and humidity will not form a high temperature and humidity adverse to the growth of orchids. Mr. Wei Yasheng, a famous family orchid grower in Beijing, raised orchids in a small greenhouse modified with east-facing windows, which was very successful, and summed up a set of rich experience of family orchid cultivation. Recently, there are new improvements to this kind of small greenhouse. In the small greenhouse, a water curtain is set up, the water is pumped to the top of the water curtain through a pump, and then it flows down by gravity. Through circulating water, it can reduce the temperature and humidity. The effect is quite good. It is said that it can reduce the temperature by 2 ℃, and the humidity can reach more than 75%. Larger orchid rooms use automatic temperature and humidity control equipment, the effect is better, but there are not many conditions for ordinary families to raise orchids. The author also saw a kind of Taiwan-made "plant cultivation box" introduced by Mr. Huang Zehua (Orchid New Spectrum, Guangdong Science and Technology Publishing House, 1996 edition, PIZ), with color photos of "planting box", which is really beautiful and generous. The basic idea is the same, that is, to create a microclimate suitable for orchid growth, but it is more advanced and can automatically control temperature and humidity, light and ventilation. Of course, the cost is also high, if the effect is satisfactory, it may be the direction of the family to raise orchids.

Of course, there are many ways to increase humidity, such as orchids and other plants, group transpiration is beneficial to the improvement of humidity in the small environment.

Author: Yu Fengyi

Mailing address: P. O. Box 5109, Beijing (100094)

Tel:010-62815876 (0)

E-mail:yfy686133@sohu.com