Indoor begonia garden can help you offset winter's snowy bleakness

Coping with the bleakness of winter is difficult for any gardener. If you live in the North, you find yourself staring dismally out the window at that snowdrift that was once a garden.

The solution is to adorn your windowsills with houseplants.

If houseplants were never your forte, try cultivating garden plants indoors. Use seed catalogs as sources of ideas.

Semperflorens begonias (technically, Begoniaceae semperflorens)m are familiar outdoor plants equally suitable as indoor companions. Favorites in bedding displays and window boxes, they perform just as impressively on a windowsill. In fact, when no longer subjected to fluctuations in the weather, these begonias may even exceed their summer performance.

Semperflorens are known by several more descriptive names. They are often referred to as ''wax begonias'' by virtue of their shiny, thick foliage, which appears to be coated with a layer of wax.

Some call them ''rose begonias,'' a name aptly describing the double-flowered form bedecked with tiny, many-petaled flowers of red, pink, or white. Single flowered hybrids display a profusion of two-petaled flowers accented by bright yellow pistils or stamens.

Semperflorens are the easiest members of the begonia family to grow. The first semperflorens was discovered by accident, a hitchhiker growing with a specimen collected in southern Brazil for the Berlin Botanical Garden in 1821.

This attests to how readily these begonias spring up from seed.

Simply sprinkle the fine seed over the top of a carefully prepared seed bed of sifted soil. Water the seed flat with a fine mist and maintain a constant temperature of 65 to 70 degrees F. until germination occurs within two months. Seed sown in August will require transplanting in October, producing a flowering specimen come midwinter.

If you prefer to purchase started plants, cell packs are available at most garden centers.

After the initial transplanting into a 21/4-inch pot, graduate pot sizes slowly, increasing one size at a time. Begonias prefer to be tightly potted and favor clay pots over plastic. A friable, humusy soil mix, such as that used for African violets, can be employed.

No further fertilizer is needed during the winter months.

A sunny windowsill, preferably with a southern exposure, is an ideal location for semperflorens begonias. Water them only when dry, and misting is unnecessary.

If the indoor atmosphere is extremely dry, added humidity should be produced. Place water on top of a stove for evaporation or put a pebble and water tray underneath your houseplants. The night temperature should not fall below 60.

The semperflorens's suitability as an indoor plant has not escaped the hybridists, and through their labors many new varieties have been created.

A series named for nursery-rhyme characters, including Pied Piper, Bo Peep, and Mother Goose, form neat sprawling baskets.

Flower types and colors also encompass the entire spectrum. Single and double varieties occur in white, pink, red, and salmon. Rarer are semi-double ''wax begonias,'' often called thimbleberries.

Foliage colors also occur in diverse shades. Green and bronze are traditional , although semperflorens also can be found with calla-lily foliage. That is, the green leaves are mottled with ivory white, each leaf unfurling like a calla-lily blossom. The green leaves of Charm are speckled with bright yellow.

Even in the dwarf varieties judicious pruning is necessary. To form a bushy specimen clip back any long flowering stems to the base where new branches initiate. This may temporarily reduce the blossoms, but it will eventually encourage more profuse bloom.

Fortunately, begonias are troubled with few pests, but if mealy bugs do attack them, get rid of them with malathion.