Rhododendron Bloom Control Techniques and Methods Explained in Detail

Rhododendron, also known as yingshanhong and juanhong, is divided into 4 categories according to flowering period and source of introduction: mao juan, xia juan, dong juan and xi juan, and the flowering period varies with the variety. If its temperature, humidity and other conditions are regulated artificially, the flowering time can be made earlier or later according to personal preference.

1. Forcing early bloom: Rhododendron flower buds generally begin to differentiate in autumn. In the cold winter season, move the rhododendron into a greenhouse for cultivation, maintain a room temperature of 20-25°C, and frequently spray water on the branches with a fine sprayer to keep humidity high; after 45-50 days it will produce dense blooms. If an even earlier flowering is needed, first give it a low-temperature treatment for 1-2 weeks before moving it into the greenhouse for cultivation, with the temperature controlled below 0°C. Then move it into the greenhouse for heated cultivation and spray water frequently, and it can bloom at the end of December or the beginning of January.

2. Delaying bloom: After the flower buds have formed, if the rhododendron is kept in a low-temperature state all along, it will temporarily not bloom. The specific method is: in early March, place the plants with formed flower buds in a cold room to avoid blooming due to the natural rise in spring temperature. The cold room temperature can be maintained at 1-3°C; water when the soil in the pot is dry, and check once every 10 days. If the storage period is long, a light should be installed in the cold room so that photosynthesis can take place. The date of removal from the cold room should be calculated according to the date on which flowering is needed and the temperature conditions at that time. For flowering between July and October, take them out about 15-20 days before the desired flowering date. The time of removal should be after 4 p.m. or before 9 a.m.; after removal they should be placed in a shaded, cool, wind-protected spot for cultivation, then sprayed with water on the plants, and after 4-5 days, once they have recovered their vitality, they can be exposed to more sunlight. A little light fertilizer can also be applied to make them bloom abundantly, with many and long-lasting flowers; even during hot weather, the flowering period can still be maintained for 20 days without wilting.