Q. My candytuft is too high and is covered with seeds. Can I cut it back? If I do will it bloom next year?

A. Candytuft (Iberis sempervirens) should be cut back to about six inches with hedges shears soon after the flowers fade. If allowed to produce seed, the flowers will be of low quality the following year. The seeds are practically worthless because they do not come true to type.

Q. I bought petunias, snapdragons and zinnias in packs, a dozen plants to the pack. They looked good when I bouhgt them but when I got them home and separated them, I discovered they were tall and spindly with no side branches.

Something tells me these plants are no good and yet it seems you can't find anything better at garden centers. What can be done to make these plants spread out and be attractive?

A. It is true that many such plants are being sold in market packs. It is also true that such plants are inferior in quality and although they are not expensive, they are not worth buying unless bought early, separated and given more room to spread out. They are tall and spindly because they were too close together in the pack and were in competition with each other for lights.

The first step with these market packs is to separate the plants as soon as possible. Then pinch off an inch of the top. This will cause side branches to develop on the lower part of the stem. Pinch a second time when the new stems are four or five inches long.

This procedure should result in a large number of flowers for arrangements in the home and a mass of blooms in the flower bed. It will also delay the plants in coming into bloom.

It is possible to buy good plants at some places. Keep looking and you will find them.

Q. Is it true that cutting off some of the small melons from a watermelon vine will result in the others being larger and better quality?

A: You may get larger melons by reducing the number on the vine but it is doubtful if quality (sweetness) can be improved. If you want extra large melons, pick out two well-shaped ones to each vines and cut off the rest. Do it when the melons are four or five inches in diameter. Use a sharp knife and make the cut close to the melon (a dull knife may bruise the vine). The best way to get top quality is not to harvest them until they are ripe.

Q: I sprayed my roses for blackspot and two hours later it rained. What did that do to the spray?

A: A certain amount is washed away in a heavy rain but some may remain, depending on whether it has dried. How long does it take for the spray to dry? On a dry, sunny day with a slight breeze, drying may be complete in one-half hour or less. On a cloudy day with high humidity and no wind, it may take several hours to dry.

If spraying is done late in the day it may not dry for a long time if dew forms on the plant at nightfall. In fact, some of the materials could wash off with a heavy dew.

When spraying plants, be sure weather conditions are such that the material can dry thoroughly before rainfall. Spraying wet foliage in the morning is all right povided the forecast calls for drying conditions for next several hours.

Q: My winesap apple trees had 12 bushels of apples last year and every one had a worm in it. How can I prevent wormy apples this year?

A: It appears to be almost impossible to grow good apples and peaches without spraying regularly to prevent insects from spoiling the fruit. Apples need to be sprayed eight times at 10-day intervals starting soon after blossom drop.

All-purpose fruit tree spray mixtures, sold under several brand names, are available at large garden centers. They give fair control of most insects and diseases that attack fruit crops. Label directions for mix and application should be followed closely.

Q: Can I prevent onions from going to seed by breaking off the seed stalks?

A: Seed stalks originate at the base of onions near the roots and by the time they are visible have already penetrated the onion completely.

Q: I have some pussy willow branches given to me by my daughter. Can I use them to start a pussy willow tree for myself?

A: Cuttings of pussy willow root readily in water or planted in the ground. Use cuttings about a foot long. If you root them in water, plant them in a pots of soil or outdoors in the ground soon after the roots are about one inch long. The roots are brittle and break easily. If you start the cuttings in the ground outdoors, keep them moist but not soggy wet.

Q: How can wild flowers be preserved so they can be used for decorations in the home?

A: In most cases, the picking of wild flowers is plain destruction. They tend to wilt quickly and then must be thrown away. They should be left on the plant to produce seed.

Many kinds of plant materials can be collected and used in dried arrangements, including cattails, cones, gourds, swamp grasses, milkweed pots, thistles, mullein, curly dock, yarrow and sandburs.