Cattalya "violacea" orchid in bloom.
image by Hellen Perrone:commons.wikimedia.org
Orchids are a diverse family of flowering perennial plants with more than 20,000 species and 100,000 hybrid varietals. While orchid care can vary somewhat among varietals, the basic elements of care and maintenance are consistent. High humidity, bright indirect light and good air circulation are the three elements that are required for any orchid to thrive, be it terrestrial or epiphytic and grown either indoors or outdoors.
Provide orchids with bright, indirect light, which is the most universally desired light level for orchids. As a general rule keep blooming orchids in dimmer light levels to preserve the bloom for the longest period. When out of bloom place in brighter light to feed the plant. Direct morning or late afternoon sunlight can be tolerated but can dry the plant so humidity and watering will need to be increased a bit to accommodate some direct sunlight. Outdoor orchids can tolerate some morning sunlight or dappled light under a pierced tree canopy.
Water your orchid regularly and provide ambient humidity for optimal plant performance. Water by holding the pot under a slow flowing stream of tepid water over the sink. Completely soak the medium and roots and allow the excess water to escape before placing back in its saucer or decorative container. Depending on your orchid type, you will either water when the planting medium is barely moist or when it has dried out a bit. This can mean watering every 5 days to every two weeks depending on the plant, growing climate and ambient humidity. Misting orchids to raise the humidity around them is always welcome and can be done daily. For dry climates or where air conditioning or heating is in use, create a humidity tray for your orchid to sit atop. Place small stones in a shallow tray or saucer and fill with water, replenishing the water as it evaporates.
Fertilize your orchid plant once a month with a well-diluted water soluble orchid food or high nitrogen general purpose plant fertilizer. Always apply fertilizer over orchid roots and potting medium that as been watered just prior to feeding. This will prevent burn to the roots and actually help with the uptake of the nutrients. Mix your fertilizer with water according to the label directions, cutting the fertilizer dose roughly in half. Less intense fertilization more frequently is preferred over heavier doses, which can damage the plant and cause the blooms to wilt. Pour the diluted fertilizer solution over the plant roots and medium, bypassing the leaves, and allow the excess solution to drain through.
Tidy and prune your orchid by removing leaves and bloom spikes after they have died back, yellowed or dried to a crispy state. Orchids draw nutrients from fading parts of the plant back into the stem and roots so always allow the plant to go through that process before cutting off stems and pulling off leaves. When an orchid leaf is ready to remove it will be wilted, yellowed and will lift off the stem with the gentlest of tugs without pulling the skin of the stem. For bloom spikes let them die back and dry in situ and when completely brown simply cut off the stem as the base of the plant with clean sharp secateurs or scissors. Pruning orchid roots is rarely a good idea as what looks dead to you may actually be live tissue. If you have completely brown, flat roots that are dessicated to a crispy state and they are protruding from the top of the plant go ahead and trim them off with clean scissors but do so sparingly and infrequently.
Repot your orchids every two to three years or when the roots are busting out of the top of the pot. When repotting step up the size of the pot between 1 and 5 inches larger in diameter than the previous one. The roots need some room to spread but planting in pots significantly larger than the root system can impede air and water flow through the roots causing rot. For terrestrial orchids use a bagged commercial orchid mix that contains bark, charcoal, peat and some potting mix. For epiphytic orchids, choose a bagged orchid mix that includes coarse bark, charcoal, and vermiculite but no soil. The former holds a bit more moisture at the root while the latter is very fast draining and drying.