Cymbidium orchids, often called “boat orchids,” are highly sought after for their large, striking flowers that can last for weeks on the plant. Compared to many other popular orchid varieties, Cymbidiums are relatively robust and forgiving, making them a good choice for those new to orchid cultivation. They are native to cooler, high-altitude regions of Asia, and their care requirements reflect this heritage, demanding a specific seasonal shift in environment to encourage their spectacular blooming. Understanding these natural needs is the first step in successfully growing these magnificent plants.
Creating the Ideal Climate for Blooming
Achieving the characteristic long-lasting blooms of a Cymbidium orchid depends heavily on providing the correct seasonal temperature fluctuations. During the spring and summer growing season, the plants thrive in moderately warm conditions, with daytime temperatures ideally ranging between 65°F to 80°F (18°C to 27°C). The most crucial environmental signal for flowering occurs in the late summer and early autumn when the plant begins to form flower spikes.
This process requires a distinct and sustained drop in nighttime temperatures, typically needing consistent temperatures between 50°F and 60°F (10°C to 15°C) for several weeks. Failure to provide this autumn chill is the most common reason a healthy Cymbidium plant will not produce flowers. While the plant is growing, it requires bright, indirect light, which is more intense than what many other houseplant orchids prefer. A simple indicator of proper light intensity is the color of the leaves, which should be a vibrant apple-green, as dark green leaves suggest insufficient light to support blooming. Good air circulation is also important, helping to prevent the development of fungal issues.
Hydration and Nutritional Needs
Cymbidium orchids are semi-terrestrial, and this affects their watering needs. During the active growth period of spring and summer, they are heavy drinkers and require the potting medium to be kept consistently moist, though never waterlogged. Allowing the roots to become “bone dry” during this phase can stress the plant and hinder the development of new pseudobulbs.
As the weather cools and flower spikes begin to emerge in the autumn, the watering frequency must be significantly reduced. The medium should be allowed to dry slightly between waterings during the cooler pre-blooming and blooming season. Using rainwater, distilled water, or reverse osmosis water is often preferred, as these plants can be sensitive to the mineral salts and chemicals found in tap water, which can lead to browning leaf tips. Maintaining moderate humidity is also beneficial, and can be achieved indoors using a humidity tray or a room humidifier.
Fertilization should be consistent during the active growth phase with a balanced orchid fertilizer. A high-nitrogen formula is used early in the growing season (spring) to support foliage and pseudobulb development. This is then switched to a lower-nitrogen, high-phosphorus “bloom booster” formula from late summer through the early stages of spike formation to promote flowering. Fertilizing should be stopped entirely during the cool winter rest period, and the potting medium should be flushed with clean water monthly to prevent the buildup of fertilizer salts.
Selecting the Right Potting Mix and Repotting
The semi-terrestrial nature of Cymbidiums means they require a potting mix that retains more moisture than coarse bark mixes. A suitable substrate is typically a blend of materials like fine-to-medium orchid bark, perlite, and coconut husk chips, sometimes including peat or sphagnum moss. This combination provides both the necessary drainage to prevent root rot and enough moisture retention to support the plant’s heavy drinking habit. When repotting, plastic pots are often favored over clay because they help to slow the evaporation of moisture from the medium.
Cymbidiums prefer to be slightly root-bound and should only be repotted every two to three years, or when the potting mix has begun to break down. The ideal time for repotting is in the spring, immediately after the plant has finished flowering and new growth is just beginning. When repotting, the plant should be removed, and all the old, decomposed mix should be carefully shaken off the roots.
If the plant is overcrowded, it can be divided, ensuring each new division retains at least three to four healthy pseudobulbs and one new growth. When placing the orchid in its new pot, ensure the pseudobulbs are sitting just at or slightly below the surface of the fresh mix, not buried deeply. After repotting, avoid heavy watering for a few days to allow any damaged roots to callus, which helps prevent fungal infection.
Diagnosing and Managing Common Issues
Cymbidium orchids are generally tough, but they can occasionally face issues, with improper care often being the root cause. Pests like scale insects, mealybugs, and spider mites are common. Scale appears as small, waxy bumps on the leaves, while mealybugs look like tiny cottony clusters, and spider mites cause a fine stippling or yellowing on the leaf surface.
For minor infestations, these pests can often be physically wiped off the leaves with a cotton swab dipped in rubbing alcohol or a damp cloth. Horticultural oil or neem oil sprays are effective methods for controlling larger populations. Fungal and bacterial diseases, such as root rot and leaf spot, typically arise from overwatering or poor air circulation, especially when the plant is kept too cool and damp.
Root rot manifests as yellowing foliage and wilting, despite the pot being moist, and is best prevented by ensuring the potting mix drains well and not allowing the plant to sit in standing water. A common non-pest issue is the browning of leaf tips, which is often a sign of mineral salt buildup from tap water or fertilizer. Regularly flushing the pot with clean water helps to wash away these excess salts.