The kinds of plants you can grow indoors usually is determined by the amount and kind of light you can provide.

Window light alone limits the varieties of plants or the areas where you can place plants. But if you supplement natural light with artificial light, you increase the potential for using plants to decorate your home or office.

Plants grow and bloom best under lighting that, like the sun, provides high intensities of blue and red radiation.

Wonderlite, a new plant growth display lamp developed and marketed in the last year, is a reflector flood light that emits both types of rays. It combines incandescent and mercury vapor lighting with a new ingredient that results in a pleasant, true daylight color most similar to sunlight.

The Wonderlite is a 160-watt bulb that looks just like the incandescent spot lamps so often used for ceiling illumination. It fits an ordinary incandescent bulb fixture but, as with all reflector bulbs, the socket must be made of ceramic material.

Incandescent reflector bulbs lack the necessary amount of blue light and have a relatively short life. Some are very hot. Wonderlite burns at a cooler temperature than incandescents. Special heat resistant glass prevents shattering from mist spraying while the lamp is it.

Wonderlite lasts 12,000 hours, as compared with less than 1,000 hours of an incandescent bulb. At present, it costs about $40 retail - about the same as lamps that are far less effective.

George Elbert, a founder and past president of the Indoor Light Gardening Society of America, estimates that the Wonderlite's "long-term cost is no greater than fluorescent installations. For instance, two four-foot fluorescent growth lamps with fixtures cost $28 or more; they cover a plant area of only four square feet. The Wonderlite bulb can illuminate at least nine square feet."

With Wonderlite you can have light where it is needed, and place plants where you want them. You can focus ligt on plants set on tables, in floor gardens or on shelves.

From the ceiling, light can be directed down on plants. The bulb can be incorporated in track lighting with light directed toward shelves. In bullet fixtures attached to the wall, plants in floor gardens can be illuminated.

Wonderlite also can provide general lighting for a room.

The Indoor Light Gardening Society of America (ILGSA) is a plant society devoted to the culture of plants indoors under artificial light. The Potomac Valley Chapter, the local ILGSA group, meets from September through May on the first Thursday of each month at the U.S. National Arboretum, 24th and R streets NE. Programs begin at 7:30 p.m.

Each meeting provides an opportunity to acquire new knowledge, special plants, seeds and supplies. Membership is open to all. For information about joing ILGSA, write to Harry McCrone, membership chairman, Crossroads, 207 Owensville Rd., West River, Md. 20881.

The Graduate School of the U.S. Department of Agriculture will offer a course in indoor light gardening, as part of its winter horticulture series, from 1 to 3 p.m. on three Saturdays, March 17, 24 and 31. The course will be at the National Arboretum Activity Center. The fee is $19. Mail registration will be accepted until Dec. 16 at the Department of Agriculture, 14th Street and Independence Avenue. SW, Washington 20250. For additional information, call 447-6337.

This course is for individuals interested in gardening indoors, as well as for those who want to support outdoor gardening with indoor propagation. It includes discussions of fundamentals of lights and equipment and demonstrations of practical procedures and horticultural considerations. The instructor is James Minogue, former president of the Potomac Valley Chapter, ILGSA.