When is the most suitable time to divide and repot orchids

When is the best time to divide and repot orchids Potted orchids are limited by their pots; vigorous, robust root clusters coil and interlace so they cannot stretch out, and they keep arching up toward the pot surface, which makes watering and fertilizing difficult. On the other hand, too many plants in the pot creates dense, airless conditions that make them prone to pest and disease damage, and also make later division difficult. For ordinary varieties, divide and repot every two or three years; for precious varieties, divide and repot every three or four years. Generally speaking, the timing of division is determined by how dense or sparse the plants in the pot are, the condition of the potting medium, and pest and disease conditions. As to exactly when to divide and repot, famous orchid growers through the ages have each had their own views: The Song Dynasty "Jinzhang Orchid Manual" records: orchids should be divided after Cold Dew and before Start of Winter (early October—mid November). This takes advantage of the time when all things return to their roots, and their leaves are then withered and their roots then old. The Qing Dynasty "Linghai Orchid Sayings" records: divide Cymbidium sinense after the Spring Equinox (March); divide autumn orchids after Minor Cold, when the old leaves have all dropped and new shoots are about to grow, and there is no failure at all. Deng Chengkang of Sichuan, in his book "Growing Orchids", advocates: orchids should preferably be divided in spring and autumn. For types that bloom in summer and autumn, divide in spring; for types that bloom in spring, divide in autumn or spring. Shen Yuan of Jiangsu says in his book "Orchids": within a year, division and repotting can be done in spring, autumn, and winter, as long as severe heat and freezing are avoided. The most appropriate time is after the 'Spring Equinox' and before 'Start of Summer', or after the 'Autumn Equinox' and before 'Start of Winter'. Mr. Li Zonghou, an orchid expert from Taiwan, China, proposes three periods in his book "Collection of Famous Flowers": first, the period when new shoots first grow; second, the period when new plants grow roots; third, after flowering. Through various experiments, I have found that the vegetative growth period and reproductive growth period of different kinds of orchid plants are very difficult to divide sharply, and often proceed in an interlaced way. Flower bud differentiation begins six or seven months before flowering; if division and repotting are done in the early flowering stage, there is a possibility of fewer flowers or no flowers; likewise, the tillering of leaf buds cannot be detected, and if division is done at this stage, the leaf buds will be injured to varying degrees. Moreover, the tillering of leaf buds and the differentiation of flower buds, besides differing by variety, also differ according to light, temperature, humidity, nutrition, the strength or weakness of the plant body's constitution, and the degree of external interference such as pests and diseases, so it is very difficult to choose the period with the least harm for division and repotting. But I have found that when flowering, the vegetative growth genes are in a diapause period; when the flowers fade, the reproductive genes enter dormancy, while the vegetative growth genes gradually shift from diapause into an active period. If we can seize the half-month after the flowers fade to divide and repot, it will neither affect flowering nor lose leaf buds, and through division can also promote leaf bud tillering. Therefore, division and repotting after flowering is the best time.