Q - We had a window box with geraniums in it last summer and they were beautiful. Can we use that same soil again this year?

A - Usually you can get much better results by using new soil every year. Almost all of the organic matter that was in the old soil is gone and it no longer has the ability to provide nutrients or to permit quick drainage of excess water. In addition, continuous fertilizing may have resulted in an accumulation of fertilizer salts in the soil, which can cause serious damage to plant roots.

Q - We have a Norway maple on our front lawn and have been unable to grow grass under it. Is there a kind of grass that can grow there?

A - If the grass can get three or four hours of sunlight daily (which seems improbable under a Norway maple) Pennlawn creeping red fescue or Kentucky 31 fescue may survive satisfactorily. Otherwise, your best bet is to use a ground cover such as English ivy or pachysandra. In shade the mowing height of the grass should be at least 2 to 2 1/2 inches. The high cutting height provides a maximum leaf area for production of carbohydrates, which are necessary to maintain root and shoot tissue.

Q - Mushrooms or toadstools are appearing in our lawn. How can we get rid of them? I don't suppose they are good to eat, are they?

A - They are probably toadstools and totally uneatable. They are caused by a fungus that grows in decaying organic matter below the soil surface. The visible toadstool does little if any harm to the grass. Pick them and put them in the trash can. Do not let children handle them. They will stop appearing when the weather becomes hot and dry.

Q - Last year the bottoms of my tomatoes split open when they started to turn red. What causes it and can it be prevented?

A - Too much rain (or watering) could cause it. The flesh of the tomato swells faster than the skin expands and the skin splits. Tomatoes should be watered every week or 10 days during dry weather, and no more often than that.

Q - I've been told earthworms are very good for improving garden soil. We don't seem to have any in our garden. Should we buy some?

A - Earthworms are usually in the top 12 to 18 inches of soil because that's where they find most if not all of their food. They are not likely to remain long in poor soil. Organic matter has to be present for them to survive; they require oxygen and can seldom be found in compacted clay soil. Improve your soil by mixing a lot of compost or well-rotted barnyard manure in it and you won't need to buy the worms - they'll come of their own accord.

Q - Our garden is small and we want to plant both pumpkins and summer and winter squash. Do we have to worry about the chance of them cross-pollinating?

A - They will cross-pollinate, but it won't affect the quality of the fruit. But don't save the seeds, because they won't be worth anything. Most pumpkins and squash grown today are hybrids, and the seeds of hybrids do not come true, so the seed wouldn't be any good anyway.

Q - Can I prevent my 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're visible they've already penetrated the onion completely.

Q - How can wild flowers be preserved for use as decorations in the home?

A - In most cases, the picking of wild flowers is plain destruction. They tend to wilt quickly and will be ruined before you can do anything with them. It's best to leave them on the plant to produce seed. Many kinds of wild plant material can be collected and used in dried arrangements, including cattails, cones, gourds, swamp grasses, milkweed pods, thistles, mullain, curly dock, yarrow and sandburs.

Q - Even before Irish potatoes were worth their weight in gold, I tried to raise some in my garden. They started out fine but later in the season dried up and died. What can be done to save them this year?

A - Irish potatoes are plagued by many different kinds of diseases and insects, and you can seldom get a crop without spraying them at regular intervals with insecticides and fungicides from the time they are a few inches high to maturity. They should be planted in acid soil to prevent a bacterial disease called potato scab. They do much better in light sandy soil than in heavy clay. They need to be watered regularly during dry weather and fertilezed occasionally.