Q: In the spring of 1975 we cut our wisteria way back after it bloomed. It did not bloom last year and this year bloomed profusely. At what time of the year should it be pruned and how much?

A: Two kinds of wisteria are grown mostly, Chinese and Japanese. The blooms of the Chinese, open before leaves appear. It often blooms a little during the summer and the Japanese does not.

Even if Chinese wisteria has room to grow freely, a considerable amount of pruning is recommended. Such pruning usually increase shoot growth and a longer blooming season the following spring. The best time to do the pruning is right after the spring blooming period.

The Chinese will make good growth and bloom well the following spring even if pruning is done several weeks later when new shoots will have become 2 or 3 feet long.

Most varieties of Japanese wisteria do not bloom well after heavy pruning or in the shade. They are suitable only for situations where they have full sun, or nearly so, and room to grow freely little or no pruning.

Q: Last year almost all of our apples were ruined. Many of them fell off the tree before they wre ripe and most of the others had worms in them. What can we do to get good apples?

A: Several kinds of insects may attack apples and the odds are against getting good fruits without spraying several times during the growing season.

Most commercial growers spray their apple trees 12 times or more each year. The fruit is kept covered with a film of insecticide to protect it from invasion.

The important thing is to spray regularly at the right time with an effective material, to spray throughly, and to keep it up throughout the season. Skip just one spraying and all your effort may go down the drain.

The spraying should start soon after the flower petals fall and continue at about 10-day intervals. The best bet for spraying, according to specialists, is one of the all-purpose fruit tree sprays which combine insecticide and fungicides, available at large garden centers under such brand names as Ortho Fruit Tree Spray, Acme Fruit Tree Spray, Miller Fruit Tree Spray, etc. Directions on the label should be followed closely.

Many gardeners do not spray their apple and peach trees and some get good fruit some years. Some of the insects that attack apples and peaches may be present in damaging numbers every year. Others may appear in a more or less cyclical pattern. Still others may be present in serious numbers for a year or two and then not show up again for several years. Unfortunately, there is no way to know in advance what will happen.

Q: Last year we moved into a house in a subdivision where the yards are, for the most part, well cared for. Our yard was almost completely covered with crabgrass.

We gave it neither fertilizer nor other special attention, yet it looked nice and green all summer long. What are the possibilities of keeping this easy-to-take-care-of grass?

A: A crabgrass lawn can be attractive during late spring and summer. Kept it cut short and water it occasionally and it stays green. In late fall it begins to look coarse but it is still green.

The first heavy frost will kill the crabgrass. At that time seed heavily with annual ryegrass. Within days the seed will germinate and you will soon have a green lawn again which will persist until crabgrass time in late spring or early summer.

Don't cut the crabgrass so close beginning in August so seed can form for next year's crabgrass.

Q: How long does it usually take for tomatoes to ripen after they first form on the plant?

A: The time of maturity of tomatoes will very according to temperature, rainfall, variety characteristics, amount of sunshine, soil fertility and garden location. Usually it is 30 to 45 day.

Q: Is sawdust okay to use for mulching my tomato plants?

A: Sawdust is an excellent material to mulch tomatoes. It reduces soil crusting, conserves moisture and helps keep the soil cool. It does not make the soil more acid.