How many centimeters should Cymbidium goeringii and Cymbidium faberi flower buds grow to before vernalization can be carried out?

The so-called vernalization means that the day-night temperature difference for the orchid's daily growth must be greater than 15°C, and the optimal time is when the minimum temperature is below 15°C. Therefore, the timing of vernalization for orchids is not determined by the flower buds, but depends on the temperature of the orchid's growing environment.

For the many orchid growers in the north, vernalization is a skilled task, because winters in the north are severely cold, and if you are not careful, the orchid seedlings can easily suffer frostbite. Based on orchid-growing experience, when the outdoor minimum temperature drops below 15°C, vernalization can begin, and it continues until the minimum temperature is around 5°C; to prevent the orchids from suffering frostbite, vernalization should be ended immediately. Do not believe what is promoted on the internet, that orchids can be kept outdoors even at minus ten-plus degrees with heavy snow sealing the mountains. Such statements harm both oneself and others, and valuable orchid plants should never be used to take such risks.

In addition, the vernalization of Cymbidium goeringii and Cymbidium faberi has a time requirement, with the optimal period being 45-60 days. If the time is too short, the vernalization effect will not be achieved; if the time is too long, the orchid seedlings are prone to frostbite, and the loss outweighs the gain.

There is no clear distinction between the start and end of vernalization for orchids. For example, wild orchids gradually experience low temperatures in the wild and bloom only when the weather warms up the following spring.

Therefore, the orchids we grow also do not have an exact time to begin vernalization. As long as we persist in letting them be exposed to outdoor temperatures and enjoy the temperature difference between day and night, that is enough. In late autumn, this is precisely when the temperature difference in orchid-producing areas is greatest; often you wear a cotton-padded jacket in the morning and drape on a thin unlined jacket at noon. This kind of temperature difference is very much liked by plants, because the energy produced during the day can be stored to the greatest extent.