Houseplants thrive in native tropics

During this chilly and rainy time of year, many folks turn to cultivating houseplants to satisfy their gardening urges. If you have houseplants, you may have wondered from which part of the world they originated. Recently, I spent 10 days in the southern Caribbean, in the tropical two-island nation of Trinidad and Tobago, located near the equator where the weather is hot and humid all year. The primary purpose of the trip was bird watching but of course I was very aware of the plant life as well. And everywhere I looked, I saw familiar plants, wild in Trinidad but usually grown as houseplants in the U.S. It was great fun to recognize old friends, and see them growing in their native environment. It gave me a new appreciation of their needs in our own cooler and drier climate, and awe at their ability to survive in the alien surroundings we offer them.

Since we were searching for birds, we spent lots of time in the rainforest on the mountainsides. There, enormous trees form a canopy that creates shady conditions on the forest floor. Younger trees and vining plants do their best to grow up into the light, and many shrubs and herbaceous plants have evolved to make the most of the dappled sunlight that can make it through the heavy leaf cover above. The frequent rains and warm temperatures keep the air saturated with moisture.

Orchids, bromeliads and ferns are abundant, rooted in the moss that forms on branches. They grow happily without soil high in the air, making do with fallen leaf litter, tiny insect bodies and any organic material that collects around their roots. The ground is covered with smaller plants and grasses, filling every available niche. The soil is poor but the constant leaf fall creates a rich surface organic layer that supplies nutrients.

The epiphytes plants like orchids and bromeliads that grow on trees in the tropics are often used here as houseplants, since they will tolerate our indoor conditions. However, our windless, dry and low-light homes do not really mimic the humid, airy rainforest.

In the wild, though warm rains are frequent and the air is moisture-laden, water quickly drains away from roots and crown. In our much cooler homes, most of us tend to overwater these plants, leading to cultural problems and disease. Orchids especially benefit from a situation that includes air movement perhaps from a ceiling fan and in winter, with fewer daylight hours and cool temperatures, less frequent watering, allowing the planting medium to dry out somewhat between irrigations. Misting can add moisture to the air around plants without saturating the growing medium, and placing the pots on saucers that contain pebbles and water so the pot bottoms don't touch the water can also add needed humidity, more closely resembling rainforest conditions.

Besides epiphytes, other "houseplants" that I saw growing there include many palm species, coffee trees, Dracaena, Begonia, Philodendron, Pothos, Diffenbachia, Ficus and Tradescantia Wandering Jew. Tiny Begonias, Tradescantias and ferns covered the steeply cut banks and stone walls around Asa Wright Nature Centre on Trinidad where we were staying, making me wish that I was able to bring cuttings and seed back with me.

Homes all over both islands displayed colorful potted plants around their doorways and front gardens, making even very humble houses cheerful and bright. And at the beautiful Cuffie River Nature Retreat on Tobago, owner Regina Sanchez showed me what she considers an exotic potted plant: our common fall-flowering favorite, a Chrysanthemum with small bright yellow double flowers. She has given them a place of honor beside her front door and said that they bloom all year long for her, needing only an occasional pinching back to keep them compact. I laughed to myself as I recognized a kindred spirit in Regina: like most gardeners, she treasures what is unusual or rare in her climate, and enjoys testing the limits of what a plant will tolerate.

-Sharon Hull