There are more than 25,000 species of orchids in 880 genera, making up about 10 percent of all the flowering plant species. There are also some 100,000 registered orchid hybrids. Of all the species of orchids, only Vanilla planifolia or the vanilla orchid, yields an edible product in the vanilla bean. While many people believe that orchids are difficult to grow, a few techniques exist that increase your chances of growing orchids successfully.
Orchids with large leaves need high light levels, while those with slender leaves need lower levels. Yellow or pale foliage can be a sign that an orchid is getting too much light. Soft or dark green foliage can suggest that the plant needs more light. Healthy orchid foliage is a consistent light green.
Many people erroneously believe that all orchids need a lot of water. In fact, forest orchids grow epiphytically on tree trunks and branches with little soil and exposed roots. Frequently soaked by rain, they dry rapidly between storms. Constant exposure to wet soil will cause orchid roots to rot and kill the plant. Water orchids tepid rainwater or distilled water and allow the excess to drain out completely. Only rewater when the substrate is almost completely dry.
Use standard houseplant fertilizer at 1/4 the recommended strength every week to feed orchids during the growing season and once a month while the plants are dormant. Choose a fertilizer enriched with trace elements. Use rainwater or distilled water to dilute fertilizer. Many orchids are highly intolerant of the mineral salts present in hard tap water.
Orchids in nature grow in areas with natural humidity of 70 percent or higher. This level of humidity is difficult to duplicate, especially inside the house. Keep several orchid plants close together to keep humidity levels high. Keep orchid pots in a shallow, pebble-filled tray but make sure that the base of the pot is not in the water itself. Avoid drafty spots, as even a light gust of air can make humidity levels plummet.
Most species of orchid thrive in daytime temperatures between 65 and 80 degrees F. Many prefer a nighttime temperature down to a minimum of 55 degrees F and will not flower without a period of cool nights.
Use commonly available shish kebab sticks to stake up flower spikes and prevent them from toppling over or snapping. Kebab sticks are cheap, sterile and long enough to hold up almost all orchid flower spikes.