Properly selected and cared for, orchids can be among the showiest and most exotic of all garden or patio plants. There are many areas throughout the southern and central United States where temperatures for a good portion of the year are compatible with the requirements of outdoor orchid growing. Some coastal areas are nearly frost-free year round. In these areas, with some protection from excessive sun, wind and rain, lovely orchid plants can be successfully cultivated on the patio or as a part of the landscape. In frost-free areas, the plants can be left in place all year. Where frost or temperatures below 40ºF threaten, plants can be brought into the home to be grown on windowsills, under lights or on an unheated patio where the coldest temperatures are avoided. The trick is in selecting plants that are already adapted to your particular area. First, though, consider some basic cultural needs of the plants.
LIGHT
No flowering plant will do well in deeper shade, and orchids are no exception. Orchids generally come from environments where dappled light is the norm. The hotter the sun, the more midday shade is required. In humid or coastal areas, more sun can be given. The required amount of light will also dictate your selection of plants. If you can offer only one light situation, select only plants that can do well under those conditions.
TEMPERATURE
In most cases, you will be limited to whatever Mother Nature provides, eased only by the amount of shade you supply. Generally, there are many lovely orchids that will do well in the temperature range from 40º to 90ºF. Your particular temperature conditions will influence your choice of plants.
HUMIDITY
Most areas with satisfactory temperatures will have adequate humidity. Anywhere from 40 percent and up will do. Only in the deserts will it be unsatisfactory. In such areas, grouping orchids with other plants can create a microclimate that will suit them.
WATERING
This will depend greatly on your plant selection, and whether the plants are grown under cover. In general: Most orchids require at least some air circulation around their roots yet are intolerant of excessive moisture at the roots.
FERTILIZER
Fertilize regularly, at a low dosage, with a fertilizer appropriate to the potting mix in which the plants are grown.
A selection of plants that may be grown outdoors
- Cattleya Alliance Hybrids: Especially good are hybrids with Laelia anceps in their ancestry; half sun, temperature-tolerant.
- Cymbidiums: Only in areas with coot summer nights, not for the Gulf states; nearly full sun.
- Dendrobiums: Among the many choices, Indian and Australian types best; half sun, temperature-tolerant.
- Encyclia Species and Hybrids: Half sun, very temperature-tolerant.
- Epidendrums: Especially the brilliant reed-stem types; need almost full sun, temperature-tolerant.
- Oncidiums: Mexican species, or higher-elevation types; bright shade to half sun.
- Paphiopedilums: Lady’s-slipper orchids are for the shaded garden.
- Phaius: The nun orchid, with broad leaves and tall spikes; shade to half sun, keep moist.
- Spathoglottis: Broad, palmlike leaves and spikes of purple and yellow flowers; shade to half sun.