Phaius tankervilleae, commonly known as the Nun’s Orchid, is a large, terrestrial orchid species valued for its impressive size and ease of cultivation. Native to the tropical and subtropical regions of Asia and Australia, this plant is a ground-dweller, unlike many epiphytic (tree-dwelling) orchids. Its common name comes from the hooded shape of its petals and sepals, which bloom in shades of rusty brown, pink, and purple with a distinct purplish lip. This straightforward care regimen makes the Nun’s Orchid an excellent choice for individuals new to growing orchids.
Essential Environmental Conditions
The correct placement of P. tankervilleae is important for its long-term health and consistent flowering. This species thrives in bright, filtered light, similar to what it receives under a forest canopy. Direct, harsh sunlight, particularly during midday, should be avoided as it can scorch the pleated leaves, causing yellow spots.
An ideal location provides light equivalent to several feet away from a south-facing window or near an east-facing window. During the active growing season, temperatures should be intermediate to warm. Daytime temperatures should ideally remain between 65°F and 75°F, with a slight drop at night to 55°F to 60°F.
Maintaining moderate to high humidity (50% to 70%) is optimal. This range can be achieved indoors using a pebble tray filled with water beneath the pot, ensuring the pot rests above the waterline. Grouping the orchid with other houseplants or using a cool-mist humidifier helps create a localized, moisture-rich microclimate. Consistent air circulation is also beneficial, as it helps prevent fungal issues like botrytis.
Watering and Nutritional Needs
As a terrestrial orchid, P. tankervilleae requires more consistent moisture than many epiphytic varieties. During the spring and summer active growth period, the potting medium should be kept evenly moist but never waterlogged or soggy. Water thoroughly until it flows freely from the drainage holes, allowing the top layer of the substrate to dry slightly before watering again.
The quality of the water used can influence the plant’s nutrient uptake. Using rainwater, reverse osmosis water, or distilled water is preferable over hard tap water, which can leave mineral salt deposits. Apply water directly to the substrate to avoid splashing the large, pleated leaves, which can encourage bacterial growth or black spots.
This orchid is a heavy feeder and requires a regular supply of nutrients throughout the growing season to support its vigorous growth and large flower spikes. A balanced, water-soluble fertilizer (e.g., 20-20-20 or 18-18-18) should be applied frequently. Many growers suggest using the fertilizer diluted to half the recommended strength with every second or third watering during the spring and summer months. Alternatively, a slow-release fertilizer can be incorporated into the potting mix at the beginning of the growing season.
Substrate and Repotting Procedures
Since P. tankervilleae grows on the ground in its native habitat, it requires a potting mix that is richer and more moisture-retentive than the coarse bark mixes used for epiphytes. The medium must still offer excellent drainage and aeration to prevent root rot, which is a common problem in saturated mixes. A suitable terrestrial orchid mix typically combines fine fir bark, peat moss, and a draining material such as perlite or sponge rock.
Some successful growers also incorporate standard potting soil or composted organic material into the mix to provide the humus-rich environment the plant favors. The ideal substrate remains loose and fertile, providing both the necessary water retention and structural support for the plant’s large size. When selecting a container, a deep, large pot is recommended to provide stability and ample room for the extensive root system this species develops.
Repotting is generally necessary every one to three years, or whenever the plant has noticeably outgrown its container. The best time to perform this procedure is in the early spring, immediately after the plant has finished flowering. This timing allows the orchid to quickly acclimate and establish new roots before the onset of the next active growth cycle. During repotting, the plant can be divided by separating the pseudobulb clumps, ensuring each new section retains at least three to four healthy pseudobulbs and a robust root mass.
Managing Seasonal Dormancy
A defined winter rest period is an important requirement for P. tankervilleae to successfully initiate its flower spikes in the following spring. As autumn transitions into winter, care protocols must be adjusted to signal this resting phase to the plant. This species benefits from a slight reduction in temperature during the winter months, preferably allowing night temperatures to drop toward the lower end of the recommended range, around 55°F.
The frequency and volume of watering must be significantly reduced once the new growth has matured and the weather cools. The goal is to keep the potting mix from becoming completely dry, providing just enough moisture to prevent the pseudobulbs from shriveling. All applications of fertilizer should be stopped completely during this cooler, drier resting period. The plant may shed some of its older, pleated leaves during this time, which is a normal process indicating the plant is conserving energy for the coming bloom cycle.