Warm winters can hurt lilac blooms

March 27, 2013|By Ellen Nibali, For The Baltimore Sun

The last couple of years my lilac hasn't bloomed. It's always been a favorite. What can I do?

There could be several causes. Because we've gotten many calls about this in recent years, it may be related to climate change. Our common lilac will technically grow in areas as warm as zone 7, but it needs a winter chilling period in order to form flower buds successfully. Other things to consider are pH (if it gets too acid, lime will raise it closer to 6.5-7), too much shade encroaching on this sun-loving plant or European hornets stripping bark and girdling branches (remove the oldest canes, which they prefer).

I put down corn gluten last fall to control fall-winter weeds and also to supply organic fertilizer. Weeds came up anyway. Any point in putting down more corn gluten now?

Corn gluten is problematic for two reasons: First, it's not very effective at preventing weeds, and secondly, at the necessary application rates, it's too high in nitrogen for Maryland. To keep nitrogen and phosphorus from damaging the Chesapeake Bay, Maryland has new fertilizer use rates. Nitrogen cannot exceed 0.9 pounds per 1,000 square feet in a single application and no more than 1.6 pounds for the year. This is plenty for healthy lawns — remember, fall application is best — but much less than the 4 pounds of nitrogen that corn gluten provides. Try another organic fertilizer or spread synthetic fertilizer and then top-dress with an organic amendment. For the weeds you are targeting, crowd them out by thickening your lawn. Overseed in late August to September.

University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to the website at hgic.umd.edu.

Plant of the Week

Yellowwood, Kentucky yellowwood

Cladrastis kentukea

When choosing a medium-size tree — for instance to replace an ash lost to emerald ash borer — consider the yellowwood. This under-planted native packs a big wow factor with its fragrant, pendulous flower panicles in May to early June. The rich green foliage stands out in any summer landscape followed by a golden yellow fall display. As the tree matures, its bark becomes smooth, gray and beech-like. Yellowwood's name is derived from the color of the heartwood. It grows to a height of 30 to 50 feet with a 40- to 50-foot spread, making it especially good on small lots. Plant yellowwood in the spring in moist soil with good drainage. It tolerates high pH, prefers full sun, and has few disease or insect problems. —Bob Orazi

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