What does vernalization mean for orchids? A detailed explanation of vernalization
Growing orchids is a profound field of study, especially for beginner flower enthusiasts, as there is so much to learn. For example, some flower enthusiasts do not know that orchid vernalization refers to the low-temperature process that orchids must undergo during their reproductive growth period; simply put, it is low-temperature treatment. The vernalization of orchids plays a role that cannot be ignored in promoting the growth of flower buds, and the vernalization time for orchids varies greatly depending on the region.
Different orchid varieties also have different requirements for vernalization temperature. For example, Cymbidium ensifolium, Cymbidium kanran, and Cymbidium sinense do not need special low-temperature vernalization to bloom naturally, but for Cymbidium sinense, the temperature from the bud stage to before flowering and even during the flowering period is best kept between 10-15°C. If the temperature is too low or too high, Cymbidium sinense is prone to developing dormant buds and bud abortion; even if it barely opens, the flowering result is very unsatisfactory and its charm is greatly reduced.
Many orchid growers wonder: when is the most suitable time to vernalize orchid plants with flower buds? For orchid growers in orchid-producing areas, there is no need to worry about this question at all; just let nature take its course (except when controlling the flowering period for exhibitions) and let them bloom normally. For northern orchid growers, timing must be chosen appropriately. Usually, when the flower bud emerges about 3-4 cm and stops growing taller, with development appearing slightly rounded and swollen, vernalization can begin as long as the temperature at the vernalization location is appropriate (4-10°C).
During the vernalization period, the ideal temperature is between 4-10°C. If the temperature is too low or too high, it will have a certain impact on the growth of flower buds, bud formation, and nutrient accumulation. Humidity should not be too high, as it easily causes root rot and bud rot. Therefore, as much as possible according to the situation, keep the plants on the drier side and delay watering time.
The duration of vernalization is provided only as a reference for orchid growers; of course, the more thorough the vernalization, the better. Usually Cymbidium goeringii needs 30-40 days of vernalization. Cymbidium goeringii in the Yunnan-Guizhou-Sichuan region has lower vernalization requirements and is relatively easier, and some can even bloom normally without vernalization. For Cymbidium goeringii in the Jiangsu-Zhejiang region, due to factors such as geography and climate, it is better to appropriately extend the vernalization time. For Cymbidium swordii and Cymbidium lianpan, about 40-50 days is suitable, while for Cymbidium faberi and Songchun, it is best to have more than 60 days. In order for orchid plants to achieve the effect of accumulating nutrients through vernalization, before vernalization, a foliar spray of 1000-fold monopotassium phosphate solution can be applied once, and then vernalization can begin. This promotes nutrient accumulation, resulting in larger flowers and more vivid colors. During the vernalization period, avoid applying nitrogen fertilizer, because at lower vernalization temperatures orchid seedlings cannot absorb nitrogen fertilizer, which easily causes fertilizer burn and root rot.
After vernalization ends, water thoroughly (avoid water entering the flower buds, which can cause bud rot), and the orchid pot can be placed in a location at about 15°C for 1-2 days, then moved to normal room temperature. This can effectively avoid heat-induced dormant buds and bud abortion caused by a sudden temperature rise. After moving to normal room temperature (18-24°C), the flower stem usually elongates rapidly (except for certain varieties), and flowers will open in about 5-15 days.
For watering after vernalization is completed, treat appropriately according to different growing media. Usually for petal-type flowers (lotus petals, plum petals, narcissus petals, etc.) and colored flowers (red flowers, golden-yellow flowers, pink flowers, etc.), try not to let the growing medium become too wet in the 7 days before and after flowering; keeping them slightly on the drier side for flowering gives more ideal petal shape and color. Otherwise, the petals will quickly elongate, the shape will change, the color will fade, and the fragrance will also be greatly reduced (after vernalization ends for colored flowers, it is best to keep the flowering period at a slightly lower temperature for better color). For exotic flowers, the opposite is true. Especially for multi-petal exotic flowers, keep them on the wetter side; if water is insufficient, some small petals will appear semi-dehydrated when flowering and will not look energetic enough. Sufficient water will make them bloom even more outstandingly and beautifully.
These are shallow remarks, and I hope they can be of some help to new orchid growers. For any shortcomings, I sincerely ask teachers to generously offer guidance.