Q. When is the latest date I can plant bulbs for next spring -- tulips, daffodils and so forth? After I buy them, how soon should I plant them? A. The best place for bulbs is in the ground unless you have a first-rate place to store them. Satisfactory storage temperature is between 55 and 65 degrees -- 63 is best. At this temperature the bulbs can be stored for several weeks without losing quality, as they would in a heated house. All bulbs should be in the ground before deep frost hardens the soil. The bulbs need a cold treatment, between 35 and 48 degrees for about 14 weeks, before blooming. If the cold is for a shorter period, the plants will not do as well. Q. I get a very nice crop of grapes but when I put them in the refrigerator to keep them from spoiling, they don't tast good afterwards. Also, how do you keep apples from going bad? A. Grapes should not be stored with other fruits or vegetables because they tend to absorb odors and this alters flavor. They can absorb odors of rutabaga, onions, cabbage and almost every other fruit or vegetable.

Most fruits should be stored at temperatures just above freezing, around 33 degrees. Q. I just discovered some Merion bluegrass seeds left over from last fall. Are they still good? A. They should be, if they were stored in a cool, dry place. If you want to make sure, you can test them indoors. Scatter some seeds on a moistened paper towel, enclose it in a plastic bag and keep the bag undisturbed in a warm room. Good seeds will sprout in 14 to 21 days. If little or nothing happens, discard the seeds. When properly stored away from excess heat and moisture, seeds should remain viable for several years. Q. I've been told I shold save my eggshells for the compost pile. Are they any good? A. These shells consist of calcium, an important element for both plant and animal life, and are worth adding to the compost. ROSE SHOW IN ALEXANDRIA -- This weekend the Garden Club of Virginia will hold its 43rd annual rose show, at Christ Church in the old port section of Alexandria. At 11 Friday morning there'll be a free lecture on the culture of roses, at the Lyceum, and the show itself will run 3 to 9 Friday and 10 to 4 Saturday. EXCURSION COMING UP -- The Potomac Rose Society is taking reservations for a one-day chartered bus trip to the Ladew mansion and topiary garden, in Monkton, Maryland, on Friday, October 19. There will be a lunch stop at Haussner's restaurant in Baltimore.For information about the fare and starting times from Washington and Silver Spring, call Mrs. H. W. Saunders at 585-2349 or write her at 505 Sligo Avenue, Silver Spring 20910. Reservations close Friday, October 12. BROOKSIDE GARDENS CLINIC & COURSE -- Next Thursday, from 1 to 3, there will be a free landscape clinic at Brookside Gardens; bring a sketch or photograph of your yard and get advice on planning and planting.

And a Tuesday-morning course on managing your own greenhouse starts next Tuesday at 9:30. The course, which covers selection, operation, plants, growing and maintenance, costs $25 and is limited to 16 registrants. To register, call Suzanne Friis, 949-8230.

Both events will be held in the library at the gardens, 1500 Glenallan Avenue, Wheaton.