There are more than 20,000 species of orchids that grow on every continent except Antarctica. Tropical orchids are good to grow as houseplants. Most grow to 12 to 16 inches tall. The plants produce flower stems throughout the year and are easy to grow. The main needs for orchids are correct soil composition and humidity level; some require a draft-free environment. Grow orchids in simple containers, terrariums or plant windows.
Replace potting soil with orchid-specific potting mix. If you bought your orchid at a garden center or a plant sale and are not sure about the soil, re-pot your orchid using special orchid potting mix designed to provide free drainage. The mixture will resemble mulch more than soil. To re-pot, remove flower stems that have towered from the base. Water the plant. Place a 1.5-inch layer of broken pottery or gravel in a new pot. Half-fill the pot with orchid mix soil. Gently remove the orchid from its container and shake the old soil from its roots. Prune dead and damaged roots, then position the orchid in the center of new pot. Gently fill orchid mix around the orchid. Lightly water to settle the mix, then add more potting mixture if needed. Leave the orchid in a shady spot for two weeks, then move it to a spot with indirect sunlight.
Create humidity for your orchid. If you live in a dry climate, or during dry periods, create humidity in your house. Ways to create humidity include using a humidifier in the room with your orchid, grouping your orchids with other houseplants (the mass foliage of grouped plants creates extra humidity), and setting pots in a shallow tray with pebbles and water. The water should barely cover the pebbles.
Place your orchid in the correct light. Certain orchids--such as the phalaenopsis, oncidium and lady slipper--do well if you place them on window panes. You can use muslin as a window screen to create indirect light before you place your orchid on windows. Heat-loving varieties, such as cattleya and vanda, do well in direct sunlight. Orchids require 10 to 12 hours of sunlight a day. Place a daylight-simulating lamp, available at most garden centers, near orchids during winter months to give the plants the light required.
Water your orchids early in the day using collected water that is at room temperature. The rain water ensures that no added chemicals are in the water you give your orchids, and watering in the morning allows the roots to dry out at night. Orchids are sensitive to outside sources, and roots can go into shock if water is too cold or too hot. Water your orchids once a week during the winter and twice a week when the weather is hot and dry. Don't allow water to get trapped between leaves. This promotes fungus and disease.
Apply an orchid fertilizer every fourth watering during growing season. Use the measuring scoop that comes with the fertilizer to ensure you get the exact amount of food to the plant. Mix as directed with water, then fertilize the orchid plant.
Place your orchid outdoors in light shade for about two weeks or more during summer months to increase healthiness of the plant. This allows the plant to get more sunlight and natural ventilation. If the orchid does not get ventilation, it can die of rot or disease. Most plants grow well indoors year-round if you create ventilation by opening windows and allowing a slight breeze during warm months, or use an oscillating fan for a few hours each day to mimic a gentle breeze.
Be sure you don't dry out plants when ventilating. Stick your finger 1 inch into potting mix; if it feels dry, water the orchid.