Many gardens in the Washington area are still producing vegetables, but the days are dwindling down to a precious one or two before the first frost.

On the average, the first frost falls between October 10th and 20th in our area. And it will put an end to the enjoyment of the endlessly adaptable and delectable vegetable -- the homegrown tomato. Though many gardeners let the frost do its damage, either by accident or design, there are many others who are constitutionally incapable of such a cavalier attitude toward their own produce.

If you have never harvested green tomatoes, because you didn't know what to do with a refrigerator full of them, give it a try. These three recipes should help.

This recipe is one made up by Sandy Blake who with her husband, Francis ranches near Big Timber, Mont. Montanans have a growing season only half as long as ours; their first frost often coincides with Labor Day. Sandy says "anything in the seed catalog that says 'earliest,' I order. No matter what it is." SANDY BLAKE'S GREEN TOMATOES MEXICAN (8 servings) 1 package of refrigerated tortillas (about 10) 3 cups creamed cottage cheese 2 cups sour cream 1 tablespoon chopped onion 6 to 8 thinly sliced green tomatoes 1 tablespoon fresh chopped coriander or cilantro (optional) 1/2 pound grated Monterey Jack cheese Salt and pepper to taste

Mix cottage cheese, sour cream and chopped onion together. Line the bottom of a 3-quart casserole with tortillas. Then make 3 layers of the cottage cheese mixture, green tomato slices seasoned with salt, pepper and coriander and tortillas again. Top with grated cheese and bake 30 minutes at 350 degrees.

Fresh coriander (or cilantro) may usually be found at the Bethesda Avenue Co-op. CHEESE RICE AND TOMATO SCALLOP (6 to 8 servings)

This recipe was clipped from the Des Moines Register about 20 years ago. Ripe or green tomatoes may be used, but this recipe particularly enhances the tart flavor and crunchy texture of green tomatoes. 3 cups cooked rice 2 tablespoons chopped onion or chopped chives 6 or so green tomatoes sliced 1/4 inch thick salt and pepper to taste 1 1/2 cups milk 1 cup shredded sharp grated cheddar cheese 1 tablespoon chopped hot cherry peppers (optional)

Mix the cooked rice with the onions or chives. Place half the rice mixture in a shallow baking dish. Top with a layer of tomatoes. Season with salt and pepper. Repeat with one more layer or rice and tomatoes. Add milk. Top with grated cheese and chopped cherry peppers. Bake at 325 degrees for 45 minutes. Green tomato chutney (2 1/2 to 3 quarts)

This very good chutney recipe is more tart than sweet. Serve as a condiment with meat, or with cream cheese and crackers as an appetizer. 1 lemon with peel, seeded and chopped 2 cloves garlic, minced 5 cups chopped green tomatoes 2 1/4 cups brown sugar 1 1/2 cups raisins 1 1/2 teaspoons salt 1/4 teaspoon cayenne pepper 2 cups vinegar 2 red peppers, chopped and seeded 1 1/2 cups chopped onions 2 tablespoons peeled and silvered fresh ginger 3 tablespoons cornstarch

Combine all ingredients but cornstach in place in stainless steel or enamel kettle. Bring to boil; reduce to simmer and simmer for about 30 minutes, until the fruit is tender. Thicken with paste made of cornstarch and 3 tablespoons water. Cook five minutes longer. Put the chutney in sterile jars and seal them according to manufacturer's directions. Or store in jar in refrigerator.