With well over 20,000 species found in a wide range of habitats on every continent except Antarctica, orchids form one of the largest flowering plant families, exhibiting a huge diversity of form.
What makes orchids so distinctive is their unique flower structure. Typically, each flower is composed of three petal-like sepals and three petals, one of which, usually the lowest and known as the lip, is often shaped differently and distinctively marked.
The majority of orchids are found in tropical regions, where most grow as epiphytes (perching on trees), their dangling roots absorbing moisture and nutrients from the warm humid air. Orchids from temperate regions are often cultivated in the garden or a cool greenhouse, but tropical types are the best for use as houseplants. Most of the species described here will grow to 12 to 16 inches (30 to 40 cm) in height and spread; some cymbidium cultivars, however, may reach 3 feet (1 m).
General care: Being such a diverse group of plants, the requirements for individuals will vary. There are, though, a few basic rules to follow. Keep out of direct light and cold draughts, and grow in a free-draining, bark-based orchid compost. This might be a mix of medium-coarse bark (not mulching bark) and perlite.
Temperature: Widely varies for individual entries
Humidity: High. Stand on dampened pebbles
Light: Bright but indirect light, or as stated
Watering: Allow compost to dry out between thorough soakings, using rainwater or cooled boiled water. Water cymbidiums, oncidiums, dendrobiums and miltoniopsis sparingly during winter, when plant growth is reduced.
Feeding: Apply an orchid fertilizer or a quarter-strength houseplant fertilizer at every third or fourth watering during the growing season.
Progagation: Division of rootball, except for phalaenopsis, which can sometimes be propagated by offshoots or stem cuttings.
Pests and diseases: Mealy bugs, scale insects
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Orchids are known for their unique flower structure.
