IF THERE is one gardening mistake we all make, at least once, it's growing too much squash. After a winter without this tender, adaptable vegetable, enthusiasm tends to outweigh judgment, and the vegetable patch is quickly overrun by creepy crawlers. We go out to pick and find inedible giants where a few days ago there were only blossoms. Even worse, our families approach mealtime with increasing dread, if not downright hostility, asking how the squash will be served today.

One hill each of zucchini and yellow squash is ample to feed a family of four all summer. If by some freak of nature your crop should be destroyed, don't despair, there will be plenty of friends and neighbors looking for someone to share their excess. If your garden has the space, try some other curcurbits instead -- hard-skinned winter squash, silly spaghetti squash, succulent melons, cooling cucumber, even small pumpkins.

The whole squash family thrives in the moist, hot, summers for which Washington is famous. They will tolerate almost any soil as long as it is well drained, though melons do best in manure-enriched loam. Mulch as soon as you plant -- black plastic warms up te soil but any mulch will hold moisture and keep weeds down.

Besides its outrageous fecundity, squash and its cucurbit cousins are big space eaters in a small garden. Try bush varieties that will grow neatly in rows -- Aristocrat Hybrid or Ford Hook zucchini; Early Prolific Straight-Neck or Park's Creamy Yellow squash; Early White Bush or Scallopini Hybrid. Winter bush varities include Bush Acorn Table King and Burpee's Butterbush.

There are even melons that can be grown as bushes not crawlers -- Park's Short 'n' Sweet cantaloupe, water-melon Kengarden and Burpee's Sugar Bush. Or try Bush Champion and Spacemaster cucumbers. Even if you've already purchased or planted crawling squash, you can still save space. They can be trained to grow on trellises, wire, even on an old step ladder -- pinch vines back when they are about five feet long.

Pick squash while it's still small and tender. It can be simply sliced for salads, chopped and added to almost any pickle recipe, sauteed, pureed, even quick-frozen and saved for winter use in casseroles. Those you overlook until you trip over them can be stuffed or grated into breads, cakes or even pies (your family will never know if you don't tell them).

Melons take much longer to mature and you will await ripening with far greater anticipation. Cantaloupes are at their peak when the fruit slips easily from the vine; watermelon is harder to judge -- wait until the bottom white spot turns yellow PATRICIA SHOAF'S ZUCCHINI SOUP (6 to 8 servings) 3 to 5 zucchinis sliced thin 3 to 5 yellow squash (same size as zucchini) 3 cups chicken stock 1/2 to 1 cup half and half or milk Fresh thyme and basil to taste Pepper to taste 1 lemon, sliced very thin

Combine zucchini, yellow squash and stock in a large kettle, cover and boil until tender (, to 10 minutes). Put in a blender or food processor a little at a time to puree (puree can be frozen for long storage). Return puree to kettle and heat thoroughly with herbs and pepper, garnish with lemon slices. Lemon is important to bring out the delicate flavor of the squash. Serve hot or cold. THEY'LL NEVER GUESS SQUASH PIE (8 servings) One 9-inch baked pie shell 2 small summer squash or zucchini (peel zucchini), grated to equal 1 cup 1 cup water Juice of 2 lemons Grated rind of 2 lemons 2tablespoons butter 1 1/2 cups sugar 4 tablespoons cornstarch 3 eggs separated

Puree squash and water in blender or food processor and pour into top of double boiler. And lemon juice and rind, butter, 1 cup sugar, cornstarch and egg yolks. Heat, stiring often until thickened. Pour into baked pie shell. Beat egg whites, adding 1/3 cup sugar slowly, until stiff, cover pie with meringue and bake in 375-degree oven until brown (about 10 minutes) MRS. FLETCHER'S FRIED SQUASH BLOSSOMS (2 to 3 servings) 12 yellow squash blossoms (male blossoms if you want more fruit, female if you're going on vacation or want to cut off plants for awhile) 2 eggs, beaten Bread crumbs 1 tablespoon flour 1/2 teaspoon garlic salt

Wash the blossoms. Dip them in beaten eggs, then the crumbs, then flour and salt mixture. Fry the blossoms in hot oil as you would oysters. Serve hot. SQUASH AND CHEESE PUDDING (4 servings) 3/4 cup pureed squash (see below) 6 tablespoons ricotta cheese 2 1/2 tablespoons parmesan cheese 1 egg 1 teaspoon nutmeg, grated 1/4 teaspoon cinnamon 1 tablespoon butter 1 tablespoon breadcrumbs Salt and pepper.

Cut the squash in half. Discard the seeds and stringy threads and place it cut side down in a lightly buttered ovenproof dish. Bake 1 hour, or until the squash is soft, in a preheated 350 degree oven. Scoop out the pulp and puree in a food mill.

Preheat oven to 350 degrees. Place all ingredients except the butter and breadcrumbs in a mixing bowl and blend well.

Butter a 1-quart baking dish and sprinkle it with breadcrumbs. Pour the squash mixture into it, sprinkle with more breadcrumbs and dot the top with butter. Bake in the oven for 30 minutes or until puffed and brown.