Q: Which kinds of maples are best for planting in our front yard? A: Sugar, red and Norway maples provide excellent shade in summer and brilliant colors of red, orange and yellow in the fall. The silver maple, on the other hand, is not recommended: The wood is brittle and the root system often causes problems with sidewalks, drives and septic tanks. Q: I had beautiful hybrid petunias last summer. One particularly was a striking beauty, red flowers with white stripes. I saved some seeds from it. What are my prospects of getting similar plants? A: Most hybrids are developed by crosses of specially selected, purified and highly inbred parents. Seeds of these F1 hybrids, if sown, would not come true -- that is, the plants would be different from their parents; 1,000 seeds might produce 1,000 trash plants, but among them might be one beautiful plant. Q: My roses were in real trouble last summer because of the black spot disease. I started spraying them in the spring with phaltan when the foliage first appeared, and two hours later it rained hard. What did that do to the spray? A: Sprays are mixtures of pesticides and water, and if they don't dry before a rain most are washed off the plants. Enough may remain to provide some protection. How long does it take for the spray to dry? On a dry, sunny day with slight breeze, drying may be complete in a half hour or less. Q: I have several red raspberry plants I want to move to a different location. When is the best time to do it? A: Spring and autumn are both good. In the spring, do it just before the plants break dormancy; in the fall, wait until the plants are dormant, usually about a month after the first frost. Q: Our grape vine was loaded with grapes last year but the birds got all of them. Is there a way to protect them so we can have some ourselves? If we picked them green, would they ripen in the house? A: Grapes should ripen on the vine. Once picked, they will not ripen any further. They can be protected by covering the vine with plastic netting, available at large garden centers and farm supply stores. The netting can be used for several years if given good care. Q: I planted two paper birch trees on our front lawn last spring. Now I've been told these trees are short-lived because of borers. Is it true? A: The natural range of the paper birch is the northern United States and Canada. South of its natural range, it is very susceptible to attack by bronze birch borers. One way to help the trees is to try to keep them in the best of health. Fertilize them in late fall after they become dormant and water them regularly during prolonged dry weather. Q: Last spring we dug up our lawn and seeded it with Kentucky bluegrass. Now we have thousands of weeds. Where did they all come from? Could there have been weed seeds in with the grass seeds? A: In many soils there are a lot of weed seeds buried deep waiting for someone to dig and bring them to the surface were they can get light enough to generate. The seeds come in by air, water, animals and man's devices. Unless the weeds are kept under control, they will quickly take over. Q: I was told eggshells were good for the garden. I put some around my tomatoes last year and they were larger than usual but didn't bear long. Were the eggshells responsible? A: It is most unlikely that the eggshells had any effect whatever on the tomato plants. The shells decay and release calcium to the soil, but it takes a long time for it to become available to the plants.