GARDENING : GROWING HEALTHY PLANTS INDOORS IS AN ART.

Byline: Joshua Siskin

Never has more information about more kinds of plants been so abundantly available. Browse the garden section of any bookstore and you will be overwhelmed by the glut of books on plants. You could buy several volumes. But then again, frustrated by this plethora of knowledge, you might just throw up your hands at the idea of becoming a master gardener and walk away empty-handed. Luckily, horticulture is an inexact science. There are plenty of gardeners in this city who have never opened a book on horticulture and cultivate magnificent gardens.

Indoor plants, however, are a different matter. For many people, growing indoor plants proves to be virtually impossible. In order to help these plantless individuals overcome their problem, perhaps we should change the category or the concept of ``indoor plants'' to ``growing plants indoors.'' Like city kids who, when asked where milk and bread come from, say ``the supermarket,'' we have to remember that the natural habitat of indoor plants is the great outdoors, albeit the tropical outdoors, and not a fancy plant shop.

Many of our rooms - in homes, apartments and offices - are inadequate to the task of providing the conditions necessary for the growth of more than a handful of indoor plants. This is especially true in winter, when central heating desiccates air that must be sufficiently humidified for indoor plants to grow; to make matters worse, relative humidity in Los Angeles is lowest during winter months. Humidifiers, which come in all sizes, can be used for maintaining air moisture in single rooms or even around individual plants.

Light is also frequently in short supply when it comes to growing healthy indoor plants. Los Angeles residences are often located on small lots surrounded by mature trees, and property lines are delineated by hedges that grow 10 feet high or more. As a result, scant light may filter through windows behind which indoor plants are placed. There is really no cure for this problem short of supplemental indoor lighting, such as that provided by grow lights or landscaping with smaller trees and keeping the hedges trimmed low. A more radical solution would be to cut through the roof and create skylight windows.

Once you've moistened the air and improved the lighting, there's the matter of watering. Most indoor plants die from overwatering or, to put it otherwise, from water that couldn't drain through the pot because the soil was too heavy. Conventional potting soil can be lightened by mixing in a generous portion of perlite. Remember that in perfectly drained soil, the danger of overwatering is reduced if not eliminated.

Another mistake is to allow water to stand in dishes that are placed beneath indoor or any other containerized plants. Plants sitting in dishes of water are susceptible to root fungus. Either water the plants outdoors or put them in shallow buckets or tubs where they can take up water, through their container holes, by capillary action; then set them on the patio or balcony to dry before moving them back inside. By the same token, a plant will happily sit on a layer of wet pebbles that fill a dish, enjoying the water vapor that evaporates from the pebble pores.

Water quality should also be a concern with a number of indoor and other potted plants such as begonias, orchids, gardenias, ferns and palms, many of which do not appreciate the hard, alkaline water that comes out of our taps. Softened, but not distilled, water is preferred by these species. The temperature of the water given to indoor plants should ideally be that of their soil, a result achieved by allowing a filled watering can to sit in your plants' room for about a day prior to watering them.

``The House Plant Encyclopedia'' (Firefly Books, 1997), is full of succinct, practical information for taking care of many of our favorite plants, nearly all of which can be grown in containers - whether indoors or out. More than 1,000 plants are illustrated together with guidelines for their care. Directions for propagation of each plant are included.

Grevillea robusta, an enormous freeway tree in the Valley that will soon be full of golden, comb-shaped blooms, is recommended for container growing. Its flowers, though, are unessential to its beauty since lacy, fernlike leaves make it a delectable study in green all year long.

Tip of the week: Not to be intimidated by indoor plants, there are several that even the most horticulturally challenged can grow. Umbrella plant (Cyperus alternifolius) is the one species on Earth that cannot be killed by overwatering. Snake plant (Sansevieria trifasciata), spider plant (Chlorophytum comosum) and cast iron plant (Aspidistra elatior) are relatively indestructible as well.

CAPTION(S):

Photo

Photo: Successfully growing indoor plants requires giving it the right light, soil, water and even making sure there is enough moisture in the air.