The White Nun Orchid, scientifically known as Phaius tankervilleae, is a captivating terrestrial orchid species admired for its elegant appearance and impressive floral displays. This robust plant is a popular choice among orchid enthusiasts due to its relatively straightforward care compared to many other orchid varieties. Its common name, “Nun’s Orchid” or “Nun’s-hood Orchid,” is derived from the distinctive hooded shape of its blossoms, which are said to resemble a nun’s veil. Originating from tropical and subtropical regions of Asia to the Pacific Ocean, including China, India, and Australia, this orchid brings a touch of exotic beauty to any collection.
Characteristics of the White Nun Orchid
The White Nun Orchid is a large, evergreen, terrestrial herb with prominent, ovoid to conical pseudobulbs, typically 60-80 mm long and 30-60 mm wide. From these emerge two to eight large, pleated leaves, linear to lance-shaped, reaching 300-1,000 mm long and 80-200 mm wide. These thin, palm-like leaves form a lush, verdant clump.
Flowering stems, or inflorescences, grow 500 mm to 2 meters tall, bearing 10 to 35 showy flowers. Each substantial flower, typically 70-125 mm wide, has sepals and petals that are often whitish outside and rusty brown or reddish-brown inside. The three-lobed labellum (lip) is commonly purplish or pinkish with a white tip and white stripes, sometimes featuring maroon highlights or a yellow spur. These fragrant blossoms last about a month, with the entire inflorescence opening over up to six weeks.
Essential Care for White Nun Orchids
Light
White Nun Orchids thrive in bright, indirect light, preferring light shade during the hottest parts of the day. An east-facing window is ideal, or a shaded south or west-facing window. Too much direct sunlight can cause leaf scorch, appearing as bleached or yellowed areas, while insufficient light may result in a lack of blooms or leggy growth. Adapt the plant to higher light levels gradually to prevent damage.
Watering
These terrestrial orchids prefer consistent moisture and do not tolerate drying out completely, especially during active growth. Maintain an evenly moist environment, allowing the top two inches of potting mix to dry slightly between waterings. Good drainage is important to prevent root rot, so ensure pots have adequate drainage holes.
Humidity
White Nun Orchids appreciate moderate to high humidity, ideally around 50% or higher. In drier indoor environments, increase humidity by placing the potted plant on a pebble tray with water, ensuring the pot does not sit directly in the water. Regular misting around the plant, not directly on foliage, also contributes to a more humid microclimate.
Temperature
This orchid species adapts to a range of temperatures, considered hot to cool growing. The preferred daytime temperature range is 15-21°C (60-70°F). They can tolerate temperatures as low as 2-4°C (35-40°F) and as high as 30-35°C (90-95°F), but prolonged exposure to freezing temperatures below 0°C (32°F) can cause severe damage.
Potting Mix and Potting
A well-draining yet moisture-retentive potting mix is essential. An ideal mix often consists of materials suitable for terrestrial orchids, such as orchid bark, sphagnum moss, perlite, and humus-rich compost or peat. This blend provides aeration for roots and sufficient moisture retention. Repotting is best done after flowering; established plants can be divided, ensuring each new section has at least four pseudobulbs for robust growth.
Fertilization
During the active growing season, White Nun Orchids benefit from regular fertilization. A balanced, water-soluble fertilizer applied bi-weekly or a slow-release granular fertilizer every three months is suitable. Avoid over-fertilization, which can lead to salt buildup and root burn. Reduce or cease fertilization during cooler, less active periods.
Promoting Blooms
Encouraging White Nun Orchids to bloom involves specific environmental cues. The primary trigger for flowering, typically in late winter to early spring, is often reduced daylight hours. Providing cooler nighttime temperatures, ideally 15-21°C (60-70°F), during autumn and winter significantly contributes to flower spike initiation. This temperature differential mimics their natural habitat, signaling the plant to prepare for blooming.
Adjusting the fertilization regimen also supports bloom production. While balanced fertilizer is used for vegetative growth, a higher phosphorus content fertilizer is beneficial as the plant approaches its blooming season. This shift provides nutrients for flower development rather than just foliage. Optimal light exposure, without direct scorching sun, during the pre-bloom period further supports the plant’s energy for producing impressive flower spikes. After flowering, removing spent spikes redirects energy towards developing new pseudobulbs and preparing for the next cycle.
Addressing Common Issues
White Nun Orchids are generally robust, but can encounter common issues. Pests like spider mites, mealybugs, and aphids may affect foliage. Spider mites often appear in dry conditions, causing a stippled or dusty appearance on leaves, while mealybugs are small, cottony masses. Regular inspection, especially of undersides, helps detect infestations early; insecticidal soap or neem oil can treat them.
Fungal issues, such as Botrytis, can develop with poor air circulation and high humidity. Ensure good airflow to prevent these problems. Signs of distress include yellowing leaves, indicating overwatering, nutrient deficiencies, or too much direct sunlight. Stunted growth may point to inadequate fertilization or root issues. A lack of blooms, despite proper care, often suggests insufficient light or cool night temperatures. Addressing these factors by adjusting care practices helps the orchid recover and thrive.