Many gardeners find the grapes they grow themselves to be a disappointment. In most cases, the poor quality of the grapes simply results from inadequate pruning.

The average vine bears more fruit than it can ripen properly, so the grapes are not as large, sweet and tasty as they should be. They don't ripen as early as they should and fruit is poorly formed. Pruning will prevent the vine from bearing too much fruit.

Pruning can be done during March at a time when the vine is not frozen. Later pruning increases the danger of knocking off tender buds as they begin to swell and grow.

If pruning is delayed until the sap begins to flow in early spring, heavy bleeding may result. Bleeding actually causes little or no harm to the vine. In a short time the wounds callus over and the bleeding stops.

To prune properly, consider the structure and growth of the vine. Arms grow from the trunk. Canes grow from the arms. The canes are brown and have smooth bark. The arms have gray shaggy bark.

Along the canes are fat growth buds. There may be an occasional growth bud on an arm or on the trunk, but most are on the canes.

When the weather gets warm in spring, these fat growth buds open and shoots grow from them. Each of these shoots usually bears two to four blossom clusters in addition to leaves. The blossoms open and bunches of fruit develop.

In general, the vine should have 40 to 50 buds after pruning is over, with four or five canes and 10 buds on each one. This could mean removal of half or more of last season's cane growth. A weak vine would have fewer buds remaining, possibly 30 to 40. One cane per arm is the best rule.

In addition to the fruiting canes, leave about 6 canes for renewal. These should be as close to the trunk as possible.Shorten these renewal canes so that only one or two buds remain on each. A strong shoot will grow from each bud and these shoots will be next year's canes.

An old vine can be rejuvenated to bear good fruit in about two years. The first step is to remove all dead and weak wood. Then shorten the trunk and arms so as to leave eight to 10 strong canes on the vine. Shorten one-half of the remaining canes to leave six to eight buds on each and cut the others back to one to two buds each. Q. Several trees that shade our front lawn discourage the grass from growing. Is there a grass or ground covering that will grow in shade and over tree roots? A. In dense shade such as beneath beech and maple trees with low branches, ground cover such as pachysandra or English ivy can be used.

If the shade isn't too dense, try Kentucky 31 fescue and mow it at a height of 2 1/2 to 3". It will be competing with tree roots for water and fertilizer; so during dry weather, water it every week, and during the growing season, fertilize it lightly every month. Q. Summer squash is one of our favorite vegetables. But in recent years the borer that gets into stem has shortened the yield from our plants. Can we do anything to prevent this? A. The squash vine borer, an inch-long white caterpillar with a brown head, enters the stem near the ground early in summer. When the vine starts to run, spray the base with methoxychlor, and repeat four times at seven-day intervals. If the borer gets into the stem, a greenish sawdust-like material call frass will show. Look for the hole and use a penknife to stab the stem and kill the borer. Then pile dirt over the injured part of the stem for new roots to form. Since the insect passes the winter in the ground nearby, planting the squash in a different place each year may help. t Q. Is there an efficient way to destroy ivy that fills a flower bed? I want to do something about it before it sprouts up again. A. The easiest and most effective way to kill the roots of ground ivy, also called Gil-over-the-ground, or Creeping Charlie, is to spray it in late April or early May when it's growing actively. Spray it with either Silvex or Dicamba. These sprays also will kill other plants in the bed. Q. I've been growing vegetables in the same plot for 15 years and quality and quantity are off despite annual 5-10-5 fertilizer. How can I invigorate the soil? A. A heavy application of organic matter, two or three inches of it dug into the soil may make a big difference. Compost, well-rotted manure and peat moss are all good to use. Lime also may be needed. Q. I've been told that when green needles fall from a pine tree it's a sign of air pollution. Is this true? A. Air pollution is far more serious and widespread than most people realize. According to Forest Service specialists, air pollution is more damaging to conifers than to hardwoods, causing loss of year-around needles prematurely. With fewer needles, the trees lose ability to maintain normal food production and are more vulnerable to insects, disease and other stress.