Windowsill 'garden' keeps growing right through winter months

Your windowsills can be working all winter long to provide you with salad vegetables, fresh herbs, and even beautiful flowering plants and cut-flower bouquets, all for the price of a few packets of garden seeds.

Many plants can be grown indoors as well as outdoors. Look through a seed catalog to find the best ones to try.

Many varieties do well in sunny or, in some cases, even shady windowsills in clay pots or rectangular plastic containers.

To start seeds, put some broken clay pieces in the bottom of a container for drainage, add potting soil, and plant the seeds to the depth suggested on the package. Here are some ideas for you to try:

* Vegetables. A number of salad vegetables make pretty greenery to enjoy while you're waiting for your ''edible crop.'' For a continuous harvest, start new seeds every three to six weeks.

Radishes. Both white icicle and round red ones are good. Radishes take between 22 and 28 days to mature to the point where you can add them to your salad.

Lettuce. The loosehead, or leaf, varieties are best and take 45 to 50 days. Lettuce will do best in a cool window. Lettuce goes to seed rapidly if it's too hot.

Carrots. Try some of the baby-carrot varieties that mature in 65 days or so.

Tomatoes. Some of the pixie hybrids are intended for both indoor and outdoor gardening. You can be eating home-grown tomatoes in 50 to 55 days.

* Herbs. These do well on windowsills, too. It's best to plant them in small containers, a few seeds at a time, or you're apt to have more than you can possibly use. If you do have extras, dry some and then put them in glass spice containers or plastic bags. They make great gifts for friends.

Herbs can be used in many ways. Chives have a mild onion flavor and the green tops are great in omelets. Anise - great in applesauce cake. Caraway seeds - use in homemade rye bread or use the young leaves in salads. Lavender - enjoy the flowers and then dry them to put in your linen closet or lingerie drawers. Parsley - easy to grow and great in salads or as a garnish. Sage - grow your own for the Thanksgiving turkey dressing.

* Flowers. A lot of garden-flower seeds also will flower indoors and provide you with both flowering houseplants or cut-flower bouquets this winter.

Marigolds, especially the dwarf varieties, will flower all winter long; also, they're easy to grow. Cornflowers, or bachelor's buttons, are very easy to grow as well. Choose the dwarf varieties if space is limited. Impatiens, or patient lucy, will give you color all winter long and will forgive you if the windowsills you put them on are often shady. Actually, they prefer a shady spot. Pansies are a little harder to grow but they will do well with care.

With common-sense gardening care, you can enjoy windowsill gardening all winter long. Children especially have a great time watching the seeds sprout; and then enjoying their harvest.