The Clam Shell Orchid, known scientifically as Prosthechea cochleata (previously Encyclia cochleata or Epidendrum cochleatum), is a distinctive and popular choice among orchid enthusiasts. Its unique common name stems from its clam shell-like blooms. This orchid’s ease of care and long-lasting, unique flowers contribute to its appeal for both novice and experienced growers.
Identifying Your Clam Shell Orchid
The Clam Shell Orchid is named for its distinctive flower, which features a non-resupinate labellum—a prominent, shell-like lip positioned at the top, unlike most orchids. The labellum is usually a deep dark purple, often with yellow-green or cream markings, forming a hood. Below it, long, thin, twisted yellowish-green petals and sepals hang downwards, giving a “squid-like” appearance. These orchids are sympodial epiphytes, producing ovoid to oblong pseudobulbs that store water and nutrients. Each pseudobulb typically bears one to three long, strap-like leaves.
Clam Shell Orchid Care Guide
Light
Clam Shell Orchids thrive in bright, indirect light, mimicking their natural habitat under a filtered canopy. An east-facing window providing morning sunlight, protected from intense afternoon sun, is ideal. Too much direct sunlight can scorch their leaves, while insufficient light may result in reduced flowering. Healthy leaves are typically a medium green, indicating proper light levels.
Watering
Allow the potting medium to dry out almost completely between waterings to prevent root rot. During the active growing and flowering season (summer through winter), watering about once per week is sufficient. When new growths mature in the autumn, reducing watering frequency to every two to three weeks is advisable.
Temperature and Humidity
These orchids prefer intermediate to warm temperatures, with a daytime range of 71-80°F (22-27°C) and nighttime temperatures in the low 60s (16-17°C). They tolerate temperature fluctuations, tolerating extremes from 41°F (5°C) to 113°F (45°C), though consistent moderate temperatures are preferred. Clam Shell Orchids appreciate moderate to high humidity, ideally between 50-70%. To increase humidity indoors, placing the pot on a tray of damp pebbles or misting the plant regularly.
Potting and Repotting
Clam Shell Orchids thrive in well-draining, aerated potting media allowing roots to dry quickly, such as medium-grain fir bark, charcoal, perlite, or coconut husk chunks. As epiphytes, they require a substrate that provides ample air circulation, not soil. Repotting is recommended every two to three years or when the plant outgrows its container, ideally in spring after blooming and new root growth begins. When repotting, carefully remove the plant, trim dead roots, and place it in a slightly larger pot with fresh orchid mix, ensuring the pseudobulbs are not buried deeply.
Fertilization
During the active growing season, Clam Shell Orchids benefit from regular fertilization. A balanced orchid fertilizer (e.g., 20-20-20), diluted to one-quarter or one-half strength, can be applied every two to four weeks. Some growers also use a phosphorus-enriched fertilizer in late summer and autumn to promote flowering. Apply fertilizer to moist soil to prevent root burn, and reduce or withhold fertilization during the dormant winter period.
Flowering and Common Challenges
Flowering
The Clam Shell Orchid is renowned for its long-lasting and often sequential blooms. Flowering typically occurs from late fall through early spring, with some mature plants blooming for several months or even intermittently throughout the year. Each flower spike can produce one to fifteen blooms, and the stems often continue to grow and produce new flowers even after older ones fade. A slight temperature drop can encourage blooming.
Common Challenges
While generally robust, Clam Shell Orchids can encounter issues. Overwatering is a frequent problem, leading to root rot, which is often the primary cause of decline. Signs of distress include yellowing leaves, stunted growth, or shriveling pseudobulbs if under-watered. Pests like aphids, glasshouse red spider mites, and mealybugs can affect the plant. Mealybugs are often found near leaf midribs, under leaf sheaths, or at the base of new leaf shoots. Ensuring good air circulation helps prevent fungal and bacterial issues.