Regular Feeding And Watering Can Keep Birch Seeds To Minimum

Q Our white-bark birch tree is covered with thousands of little sawdust like seeds every year. I have two trees and they are tall, which we need for shade during the summer months. They are beautiful trees, but their mess is something else. Is there something I can do short of cutting them down?

A Birch trees will sometimes set seed if they are under stress, because this is their way of reproduction. So sometimes if one begins a regular program of feeding and watering, the improved health will result in less setting of seeds. The best time to fertilize a birch tree is in mid-February. Use a rose or all-purpose garden fertilizer to feed them. Make some holes around the base of the trees, at the drip-line of the tree. Use a pipe or crowbar, or root feeder to make the holes. Make them eight to 12 inches deep, and pour the fertilizer down the holes, watering it in thoroughly after application. If you ever need to replace the trees, there are some gorgeous varieties of flowering plums, crab apples and flowering cherries that might be just right for shade and color.

Q I have a gardenia plant that was given to me last Mother's Day. It had eight buds; four flowers developed, but the other four buds dropped off. Then later, three new ones made it. Now I wonder what to do for it. Should I re-pot it, to a larger pot? I have it in my bathroom, where the diffused window faces west. I gave it Miracid to start, but am now using another type of fertilizer. Any hints?

A First, make sure the plant gets about 14 hours of light a day. Second, make sure the gardenia is fertilized with an acid fertilizer like Miracid, Fish Fertilizer or Liquinox. Third, only re-pot the plant if it is root-bound. Then only repot it into a pot that is one size larger than the original. Fourth, once the flower buds form on the plant do not turn the plant, for any reason. That is a sure way to lose the blossoms.

Q We have several apple and pear trees and are really confused as how to prune them. Plus, there are several ornamental plants that we are not sure how or when to prune. Do you have any suggestions for a pruning book that would help us?

A If you are a new homeowner and faced with pruning for the first time, I would suggest that you select a pruning book that has a lot of example pictures. Two books that immediately come to mind are the Ortho and Sunset books on pruning. Ortho's is ``All About Pruning''; Sunset's book is ``Pruning Handbook.'' Two other books for more advanced gardeners are ``Pruning Simplified'' by Lewis Hill, Gardenway Publishing, and ``How to Prune Almost Everything'' by John Philip Baumgardt, M. Barrows & Company, Inc. The Ortho and Sunset books are available at nurseries, garden centers, hardware, garden outlets and book stores. The last two books are probably easiest to find at book stores or directly from the publishers.

Q During the summer I battled powdery mildew on my rose bushes. I have just winterized them and noticed under all the beauty bark a white powdery substance on the underside of the bark. Is this also powdery mildew? How do I treat this condition?

A It's not likely that the white powdery substance is mildew. It is probably one some saprophytic fungi that is decomposing the bark. So there is no need to take any corrective steps.

Gardening by Ed Hume appears Friday in the Scene section and Sunday in the Home/Real Estate section of The Times. He cannot respond to personal inquiries by mail but will answer questions of general interest in this column. Address questions to Ed Hume, c/o The Seattle Times, P.O. Box 70, Seattle, WA 98111.