Ground orchids, also known as terrestrial orchids, grow directly in the soil, unlike their epiphytic relatives that cling to trees or rocks. This difference means ground orchids, such as Spathoglottis or Paphiopedilum species, require a different approach to cultivation. Terrestrial varieties behave more like typical garden plants, growing from rhizomes or pseudobulbs buried beneath the surface, rather than needing bark-based mixes. Understanding their specific needs is the first step toward successfully growing them.
Establishing the Ideal Environment
Terrestrial orchids thrive in conditions that balance light, temperature, and humidity. Most ground orchids prefer bright, indirect light, such as partial sun or dappled shade. Too little light inhibits flowering, resulting in dark green foliage, while too much direct sun can scorch the leaves, sometimes indicated by a bleached or reddish edge.
Temperature requirements vary, but tropical ground orchids generally prefer 65°F to 85°F during the day, with a 10°F to 15°F drop at night to promote blooming. Many outdoor varieties tolerate a wider range, and some require a cool rest period to flower the following spring.
Humidity levels between 40% and 70% are beneficial, helping reduce water loss through the leaves. Unlike epiphytes, terrestrial orchids do not absorb water through their leaves, making misting less effective.
Substrate and Planting Requirements
The growing medium for ground orchids requires a blend that retains moisture while offering excellent drainage and aeration. Since terrestrial orchids are prone to root rot, the mix must prevent sogginess.
A suitable potting blend incorporates loamy soil, which is light and non-compacted, mixed with organic material like peat moss, compost, or vermicompost. To ensure superior drainage, components such as perlite, fine-grained fir bark, or charcoal should be added to the mixture. A common ratio for container-grown plants is 60% loamy soil or peat with 40% perlite and bark.
When planting, ensure good drainage by using pots with holes or amending heavy garden soil with grit or organic matter. For orchids growing from shallow rhizomes or pseudobulbs, the container width is often more important than the depth.
Essential Routine Care
Consistent hydration and appropriate feeding are essential components of routine ground orchid care during the active growing season. While they tolerate more moisture retention than epiphytes, watering should be done thoroughly, allowing the top two to three inches of the potting mix to dry slightly before watering again. The frequency of watering depends on environmental factors like light, temperature, and the specific mix used.
Fertilization is most effective during the vegetative growth period, before flower buds appear, and should be applied regularly in a diluted form. A balanced water-soluble fertilizer, such as a 20-20-20 formula, is recommended. The “weakly weekly” method involves feeding the orchid with a highly diluted solution at nearly every watering, or at least once a month. To prevent the build-up of mineral salts, flush the pot with plain, clean water at least once a month.
Addressing Common Issues and Dormancy
Managing pest and disease risks is important for ground orchids, which are susceptible to issues common to both traditional garden plants and other orchids. Pests like slugs and snails can be a problem for terrestrial types, particularly in garden beds, while common orchid pests like scale and mealybugs may also infest the foliage. Fungal issues, such as root rot caused by organisms like Pythium and Phytophthora, frequently result from overly wet or poorly draining soil.
Minor pest issues can be treated by physically removing insects with a cotton swab dipped in isopropyl alcohol or by using horticultural soap. Fungal root rot requires immediate action: remove the plant, trim all dark, soft, or foul-smelling roots with sterilized shears, and repot in fresh, well-draining substrate.
Many ground orchids, especially those from temperate regions, enter a natural dormancy period during cooler months. During this rest phase, the plant may lose leaves or its growth will slow, requiring a reduction in both watering and feeding until new growth appears in the spring.