On a gray February day, gardeners may be looking at colorful seed catalogs or even holiday brochures, dreaming of a trip to a tropical island. But this week it's time to leave your armchair gardening, because the tropics have come to Tokyo. The Japan Grand Prix International Orchid Festival offers a dazzling display of flowers, from showy tropical beauties arranged in great cascades of color to tiny wildflowers nestled in moss.

This is the largest orchid festival in the world, attracting amateur and professional growers from Japan and more than 20 other countries to its competitions and displays. Many specialists from countries as far afield as Hawaii and New Zealand have also brought plants for sale. So, if you are looking for a pretty houseplant or a special garden plant, you are bound to find something that will brighten up the last days of winter.

With more than 17,500 species, the Orchidaceae family is second only in size to the daisy or Compositae family of plants. The variety is almost overwhelming, but it helps to think of them in two major groups: the epiphytes, or air-loving types; and the terrestrials, or ground-hugging types. Many of the most gorgeous orchids, such as the cattleyas from the South American rain forests, are tropical epiphytes that grow by clinging on to rocks or trees. A minority, however, such as Japan's dainty ebine (literally, "shrimp-root orchid," known in English as the calanthe), grow in temperate woodlands or marshes, and these are mainly terrestrials.

While flamboyant orchids are very popular, and often pop up in wedding bouquets or hotel lobbies, other varieties are prized for their quiet beauty. For example, the oriental cymbidiums (including Japan's shun-ran, or "spring orchids"), usually have green or ivory-colored flowers that peep out from long slender leaves. Some are also fragrant, and for centuries Chinese and Japanese artists have enjoyed capturing their elegant lines with a few strokes of the brush.

Yet other varieties are prized for the rare beauty of their leaves, as you can see in the festival's display of "jewel orchids."

Luring visitors

For all their variety, however, orchid flowers follow a similar pattern: They are usually made up of three outer sepals and three inner petals. The low, middle petal is often the largest, acting as a lure, or "landing pad," for visiting insects. As for all those spots and stripes, they attract pollinators such as butterflies and bees.

This year's Grand Prix winner, Osamu Nobuhara from Bizen City in Okayama Prefecture, produced a plant with four superbly patterned blooms. As he received his 2 million yen prize money, though, he joked, "All I did was give it food and water!" In fact, according to the chief judge, Robert J. Griesbach, this hybrid orchid (Paphiopedilum rolfei) "is produced from two distinct species of parents, and we just don't know what triggers it to flower. It may only produce a single flower after many years -- if at all."

Indeed, one of the reasons that orchids are popular hobby plants is because they are full of mystery and challenge. Just consider how one of these exotic plants starts life in a rain forest. The seed is as fine as dust, so that it will lift and travel on the gentlest breeze. Unlike heavier seeds that carry their own food supply, orchid seeds need help in order to germinate, and this arrives in the form of a friendly fungus. The fungus invades the seed and gives it enough energy to develop a small corm. Gradually, the corm sprouts tiny leaves and roots. The roots are used to anchor the plant to its tree, but the orchid is not a parasite and is able to draw energy from sunlight and moisture.

Commercial nurseries imitate nature by growing seeds in a jelly primed with nutrients. But this takes time, and orchid seeds are very unpredictable, often sending up flowers quite different from the parent plant's. So to reproduce a promising hybrid in large numbers, a nursery will usually clone it via stem cuttings.

Fortunately, growing orchids in the home does not require laboratory conditions, as we can start off with ready-grown plants. Potted slipper orchids, for example, will be happy as long as they never dry out. However, they need gritty, free-draining compost in order to avoid root rot. The temperature must not fall below 10 degrees and they need plenty of indirect sunlight. Keen amateurs often use fluorescent-light cabinets to encourage growth.

Garden orchids are generally much easier to handle, as I discovered almost by chance. One variety is the beautiful white or amethyst-colored shi-ran (Bletilla striata), and two pots of this on my balcony are already sending up green shoots.

Bulblike critters

Originally, I bought a small shi-ran plant in order to sketch the flowers, and later put it outside without much hope. In winter, its leaves turned brown and fell off, but there were some interesting bulblike critters in the pot so I left it to have a rest. Luckily, the following spring these "pseudo" or false bulbs sent up new shoots and bore lovely flowers in May.

You can increase these plants by splitting off the leafless brown bulbs in early spring and planting them separately. Be sure to leave at least four green bulbs on the parent plants, repot them in good, well-draining compost and feed them to encourage flowering.

Japan is home to a number of lovely wild orchids, including the speckled-pink kumagai-so (Cypripedium japonicum), which has a puffy pouch and crisp, circular leaves that look as if they have been trimmed with scissors (some of these are on show at the festival.) It is thrilling to find orchids growing in the wild, but terrible to hear of colonies dying out because people have stolen them for their gardens. And how pointless it is to do so. Wild orchids usually die when they are dug up, and anyway, many are available from specialist growers.

I bought a delightful, fragrant pastel-colored ebine orchid at the show for just 2,000 yen. These orchids usually flower in April or May, so I will keep it indoors until it has finished flowering, then plant it outside. On the balcony or in a sheltered spot in the garden, it should survive to flower in future years.

Assam sensation

Unfortunately, orchids excite such passionate interest that they have a history of exploitation. It makes one's blood boil to read of 19th-century plant-hunters slashing down forests in their search for rare flowers. Some hunters destroyed all the plants they could not send back to Europe in order to prevent others finding them. And Assam's deep-blue orchid, the Vanda coerulea, caused such a sensation when it appeared in Victorian flower shows that ruthless collectors nearly hunted it to extinction.

Today, loss of natural habitat is another huge threat to wild orchids' survival, but organizations such as the American Orchid Society are trying to help. With 25,000 members worldwide, this is the largest plant organization in the world. Chief judge Griesbach, a third-generation orchid specialist and president of the society, assured me that half of their activities are related to conservation. "As well as influencing international treaties and laws, we go in to rescue plant species and habitats, seed pods and so on," he said. "We also give research grants. For example, a recent research project found that ants are essential to pollinate certain native Australian orchids, and this kind of information is vital to conservation."

It seems that orchids need as many friends as they can find.