ASK THE GARDENERS. Questions & Answers

Q A few weeks ago I read an item in your garden column which indicated it was an ultimately destructive practice to mulch trees with shredded or chipped bark. To my dismay, I see that our city forestry department has mulched every tree in our area with bark. I am concerned about the results. C.H.

Madison, Wis.

We believe the column you refer to (mid-July) was from a reader whose husband had banked sawdust around her roses for winter, and they had died.

In elaborating on the fact that sawdust under certain conditions would form an alcohol harmful to plant tissues, we said: ``Landscapers have discovered that trees which are mulched heavily with shredded bark so that it reaches several inches up the trunk can cause fatal injury to the cambium layer.'' The key phrase is ``so that it reaches several inches up the trunk.'' We offered the precaution: ``It is now recommended that bark chips or shredded bark be pulled away from the trunk to leave it exposed to air.''

In other words, bark materials are fine for mulching, but they should be pulled away from the trunk, leaving a saucerlike depression so air can circulate freely in that area. Thank you for giving us a chance to clarify this. There may be others who misunderstood the explanation.

Q Can you help me with a garden problem I have had for over 20 years? The florets in the center of my geranium blossoms come out and then fade before the surrounding florets open. Consequently, lower buds form a lower layer, with no fresh blooms in the center.

Friends' geraniums appear to have showy blooms, with all buds opening at once. How can I get my geraniums to perform like theirs?

T.C.W.

Orono, Maine

Geranium blooms are composed of many florets which move upward as they color and open. Some geraniums produce more florets per head and fill in where florets have faded and dried. One of the objects of plant breeders has been to get varieties (cultivars) with florets that form a long-lasting head that does not shatter (shed petals). We suspect your friends have some of these varieties. Also, they may have them planted in locations that get early morning sun, late afternoon sun, or both, but not hot midday sun. Hard rains may damage blooms, especially centers.

Observe where their geraniums are planted, then ask what variety they have. Compare different varieties from garden stores, and see which do best for you.

COMMENT: A while ago, there was an article in the garden section pertaining to marigolds. It included an invitation to join the Marigold Society of America, but an incorrect address was given. Although this did not appear in your question-and-answer column, perhaps you would give the correct address: Miss Jeannette Lowe, 394 W. Court St., Doylestown, PA 18901.

We are happy to comply. The Marigold Society is a fine organization, providing members with much good information. Miss Lowe is a member of the Garden Writers of America and is an extremely knowledgeable horticulturist, having worked for many years with one of the largest seed firms in the country.

Doc and Katy Abraham are nationally known horticulturists.