How to Control an Overly Early Blooming Period in Cymbidium Hybrids

When the blooming period falls outside the main sales season, the flowers not only fail to fetch a good price, but sales volume is also very limited. What factors cause Cymbidium orchid blooming periods to come too early? When early blooming is detected, how should growers respond and remedy the situation? On this topic, Mr. Tomohiko Sakuruma, who has worked for 32 years on Cymbidium hybrid-related work at Kono Mericlone Co., Ltd. in Japan, shared his experience.
Cymbidium hybrids
Choose good varieties and keep proper production records
    To regulate the phenomenon of early blooming, one must first understand the causes of early blooming. Sakuruma analyzed that there are many reasons causing Cymbidium hybrids to bloom too early, including variety characteristics, weather conditions, the timing of retaining flowering buds, and the temperature, light and fertilizer conditions inside the facility. Regarding varieties, this involves the source of the varieties. At present, China mainly plants Japanese seedlings, generally obtained through tissue culture. Most of these varieties were obtained by crossing and improving large-flowered European types with local Japanese varieties, and the breeding goal for the blooming period was to meet demand around New Year in Japan. Therefore, when used for production targeting the Chinese Spring Festival, early blooming often occurs. For this reason, Sakuruma suggested that growers should first choose different varieties with early, middle and late blooming periods according to the climate conditions of their own bases and their existing facility conditions.
Weather conditions and the facility environment are also important factors affecting the blooming period of Cymbidium hybrids. In the second half of this year, Kunming, Yuxi and other places in Yunnan had many clear days, flower buds grew faster, and most growers used simple greenhouse temperature control equipment, leading to an earlier blooming period. Sakuruma told reporters that some growers in Yunnan used greenhouses originally for producing herbaceous flowers or cut flowers for Cymbidium hybrid production. Although these were renovated, they still could not well meet the temperature and light requirements for blooming period regulation of Cymbidium hybrids. Professional facilities are a guarantee for effective blooming period regulation.
The timing of retaining flowering buds has a direct impact on the blooming period. Growers generally count backward from the optimal sales period to determine when to retain buds. For example, large varieties generally need four to five months from the appearance of flower buds to market, and about forty to fifty days from the beginning of bud emergence to the opening of the first bud. If the target is January market, then August buds are suitable. This is a common rule. However, considering factors such as weather and pot diameter, growers are often afraid that the plants will not bloom by the sales season, so they usually retain buds earlier. In addition, 4-year-old plants of the same variety grow vigorously, and with the same bud retention time, they often bloom earlier than 3-year-old plants. This is also one reason why some Cymbidium hybrids bloomed earlier this year.
In this regard, Sakuruma said that data is the best basis for production operations. Growers need to arrange operations according to their own actual conditions, understand the regional climate and greenhouse characteristics well, and record various data on the blooming conditions of different varieties observed each year, such as which day buds were removed and how many times buds were removed, for reference in the next year. Only by accumulating experience year by year can the blooming period be well controlled in a region.
Shading and cooling during the blooming season to control the blooming period
Before the end of November this year, many Cymbidium hybrid buds in Yunnan had already opened. Yunnan Kono Kyodai Agricultural Technology Co., Ltd. has always approached flower control from two aspects: first, pulling shade nets, with one layer of outer shading at 50% shading rate and two layers of inner shading at 30%, and from October to November all three shade nets were pulled over. In early December, the light intensity in Kunming is about 90,000 lux. After three layers of shading, in some areas the light can drop to two thousand to three thousand lux, which is relatively suitable for controlling very early-blooming varieties; second, ventilation and cooling, opening both sides of the greenhouse and ventilating 24 hours a day so that cold air at night enters the greenhouse. If the temperature inside the greenhouse is kept below 20°C during the day and at 4°C at night, the blooming period can be effectively controlled. “We did experiments. In a room at 5°C to 7°C with no light, Cymbidium hybrids basically go dormant and do not grow, and the buds do not change color. Based on this phenomenon, different degrees of early blooming symptoms can be treated with different degrees of shading and temperature control.” Sakuruma said.
Some growers worry that low temperatures are unfavorable for ensuring the quality of Cymbidium hybrids. Sakuruma said that as long as the temperature is not too low, there is generally no impact, and it may even improve the quality of some varieties. For example, in pink-flowered varieties, low temperatures help coloring and make the flower color better. Some varieties have already colored before shading. If only shading is used and the temperature cannot be lowered, the flower color may gradually become lighter. Only when the temperature is a bit lower can the flower color be ensured while also achieving the purpose of flower control. During the shading and flower-control period, water only when the pot is very dry. In the current season, the Kono Yunnan base generally waters once every three to four days. Too much water can cause rot at the base of the flower stalk.
When the blooming season is needed, the light exposure rate should be increased step by step. Kono Kyodai’s approach is: first remove two layers of inner shading to let light increase partly, and after the temperature rises somewhat, pull back the outer shading; watering also gradually transitions from once every three to four days to once every two days, and then to once a day. If all shade nets are opened at once and the flowers are directly exposed to the sun, dried buds are likely to occur.
During the shading-based flower-control period, some varieties also perform differently from their normal blooming period. For example, under shading conditions, the flower stems of ‘Pianist’ are relatively soft, and if not supported in time, they tend to bend. Sakuruma suggested using flower stem guide hooks, which can adjust the position of the flower stems at any time so that the finished flower stems remain upright and straight.