Hibiscus, bougainvilleas, philodendrons and so many of the tropical and subtropical plants that we can enjoy in our gardens can only survive through winter in greenhouses in most other climates in America. Many of our tropical houseplants though, seem to be the same everywhere. Houseplants are generally grown in our homes not because they cannot survive in our gardens, but because they can survive in our homes.

Yes, houseplants are merely any plants, tropical or otherwise, that we grow in our houses. Yet, most and perhaps almost all of the plants that are best adapted to surviving as houseplants happen to be tropical plants.

Tropicals do not need the seasons that they would get outside. Because many are native to dense and very competitive tropical forest environments, they are adapted to the sort of shade that they get in our homes, and survive on minimal volumes of soil that they have available while potted.

Nonetheless, they miss their tropical lifestyles. They tolerate dry interior air, but would prefer more humidity. They would likewise prefer to be rinsed of dust more often than they can be in indoors. A regular supply of fresh organic debris to supply nutrients would be nice. However, if merely fertilized instead, tropicals are sensitive to salts and other toxins that eventually accumulate in the soil.


This is why some of the more resilient houseplants like to be brought outside for a gentle rinsing during a mild rain. As long as it is not too cool or windy, gentle rain rinses dust from the foliage and toxins from the soil. Plants can be brought out in the morning and brought in late to get as much time out in the rain as possible, but should not be left out overnight when it may get too cool. Even though they do not need any more moisture, plants can be watered by hose a few times to allow water to rinse freely through the soil.

Plants in overly decomposed potting soil are easier to repot with fresh soil while they are outside. Those that do not need to be repotted might still like getting grungy and potentially toxic mineral deposits scrubbed from their pots and drainage pans.

Flower of the Week: Hibiscus

This humongous 6-inch-wide tropical hibiscus, Hibiscus rosa-sinensis, looks like it might be from Hawaii or Florida, but was actually found in K and K Nursery and Landscape of Norman, just south of Oklahoma City, where winter nights are already seriously cold by our coastal California standards. It is happy to bloom so impressively only because it is in a greenhouse.

Even here in our pleasantly mild climates, tropical hibiscus are happiest where sheltered above from frost, by eaves or evergreen shade trees that are high enough to also allow warming sunlight through. In the cooler spots, even sheltered plants occasionally get damaged by frost, and need some time to regenerate after winter.

Some of the classic tropical hibiscus that typically have smaller flowers can grow above single story eaves if not pruned down. Most modern varieties with larger or ruffly double flowers rarely reach the eaves, and many stay less than 6 feet tall even without pruning. The evergreen foliage has an appealing glossy sheen, which is an ideal backdrop for the red, pink, white, yellow or orange flowers.

Horticulturist Tony Tomeo can be contacted at 408.551 9931 or lghorticulture@aol.com.