Q. Will planting marigolds in my vegetable garden really ward off insects as I have read?

A. Many gardeners strongly believe in companion plantings using marigolds, rosemary, nasturtiums and other plants. We can find no data to prove or disapprove the value of this.

Q. Last spring we planted shallots and they were very small. How can we improve their size? Should they be harvested when the tops turn brown?

A. Most likely the small size of the cloves was due to poor soil, too much competition from weeds, or not enough sunlight. Cutting off the tops for seasoning also will prevent normal clove development.

The cloves should be dug in the fall when the foliage turns yellow or brown. Dry them for two or three days, then cut off the tops and store as you would onions.Q. Is it possible to grow globe artichoke outdoors in the Washington area or in a container on a sunny windowsill?

A. One of the few places where the globe artichoke grows outdoors is along the California seacoast. The growing season outdoors in the Washington area is not long enough. It is not suitable for growing in a container because it takes up too much room, about 18 square feet, if it is to provide fruit. It can be grown in a greenhouse where the environment can be controlled.

Q. Odd and ugly growths appeared on the tip ends of some of the stems of my lovely pink azalea. Can you tell me what it is and what I can do about it?

A. A fungus infection called azalea leaf and flower gall causes the leaves to become swollen and curled. They turn pale green to white or pinl during the early stages, and brown and hard later on. These galls are made up of abnormal tissue.

The galls do no great harm to the plant. Pick them off and put them in the garbage can. That should take care of it. Sometimes they spread to flower petals of evergreen rhododendrons. if they do, pick them off and dispose of them.

Q. Even before white potatoes were worth their weight in gold, I tried to raise some in my garden. Each year they started out fine but later the shoots dried up and died. What is the secret of success with them?

A. White potatoes are plagued by many different kinds of disease and insects. It is almost impossible to get a crop without spraying them at regular intervals from the time they are a few inches high until maturity.

To start, it is necessary to buy certified seed potatoes. This will provide some protection against some of the diseases. They should be planted in acid soil to help prevent a bacterial disease called potato scab.

They do much better in light sandy soil than in heavy clay. They need to be watered during dry weather and fertilized occasionally.

Some of the diseases include early blight, late blight, fusarium and other wilt diseases, virus disease, scab, ring rot and black rot.

Almost a dozen different kinds of insects may attack potatoes.