Cymbidium orchids are a popular choice for home growers because they are relatively hardy and produce striking, long-lasting flower sprays. The primary challenge for many enthusiasts is convincing them to rebloom after their initial flowering. Successfully triggering a new bloom cycle requires the grower to accurately mimic the plant’s natural seasonal cues, specifically through careful adjustments to light, temperature, and feeding schedules.
Essential Light Requirements for Bloom Energy
The foundation for future flowers is built on the energy reserves stored in the plant’s pseudobulbs. Cymbidiums need bright, filtered light throughout the spring and summer growing season to accumulate enough energy to support a flower spike. Optimal light levels are typically between 3,000 and 6,000 foot-candles, which translates to a south-facing window shaded by a sheer curtain or a location that receives several hours of morning sun.
A plant receiving sufficient light will develop leaves that are an apple-green or yellowish-green color. If the foliage is a deep, dark green, it suggests insufficient light, and the plant is unlikely to bloom. Conversely, too much direct, intense sun can cause leaf burn and bleaching, which damages the plant’s ability to create food.
Temperature Differential for Spike Initiation
The primary trigger for reblooming is providing a cool rest period. This process, known as spike initiation, must occur in late summer or early autumn. The plant requires a consistent temperature differential between day and night for several weeks to form a flower spike.
Cymbidiums need daytime temperatures around 75°F (24°C) but require nighttime temperatures to drop significantly into the 50–55°F (10–13°C) range. This 15 to 20-degree drop initiates the formation of flower buds rather than new vegetative growth. Without this distinct cooling period, the plant will continue to produce lush foliage but fail to bloom.
Achieving this differential involves moving the plant outdoors during late summer, placing it in a protected area where it benefits from the cool night air. The plant should be moved back indoors only when there is a risk of frost, which typically occurs when temperatures fall below 40°F (4°C).
Adjusting Fertilization Cycles
Nutrient application must be timed to support the two distinct phases of the Cymbidium’s growth cycle. During the active vegetative growth phase in spring and early summer, the plant needs a high-nitrogen fertilizer. A formulation with a high first number, such as a 30-10-10 ratio, supports this vigorous growth.
As late summer approaches and the cool rest period begins, the fertilization focus must shift to avoid encouraging continued leaf growth. The grower should switch to a low-nitrogen, high-phosphorus and potassium formula, such as a 3-12-6 ratio. Continuing to feed with high nitrogen at this stage can inhibit flowering.
Post-Flowering Care
Once the current season’s flowers have faded, the grower must prepare the plant for the following year. The spent flower spike should be cut cleanly, using a sterilized tool, down to the base of the plant. This removal directs the plant’s energy toward new vegetative growth.
Repotting should be performed after flowering, during the spring when new growth and roots are beginning to emerge. Cymbidiums prefer to be slightly root-bound, so repotting is necessary every two to three years, or when the potting medium has decomposed. This is the appropriate time to inspect the plant and remove any shriveled, leafless backbulbs.