A tall, lanky lilac should grow thicker with renewal pruning


Backyard Q&A

In the Garden

May 16, 2004|By Dennis Bishop | Dennis Bishop,Special to The Sun

We have an old lilac shrub that has gotten tall and lanky. If we cut it back now, will the plant thicken up?

As lilacs mature, they often get lanky and become dominated by a few old branches. However, they do live for many years and regrow well after renewal pruning. Plants respond best to this type of pruning in early spring, but if you prune your lilac in the next few weeks, it should be fine.

The goal of renewal pruning is to remove some of the old dominant branches so that new branches grow from the base. The old branches should be cut about 6 inches from the ground or just above a new sprout. After the pruning, new sprouts will develop and grow. In some cases, only a few new sprouts will develop, but in other cases dozens of sprouts will emerge, and they will need to be thinned out.

Because there are many types of lilacs with many different branching patterns, I cannot tell you how many branches to leave. I would simply thin out the sprouts until the plant looks full but not congested with branches. Renewal pruning also works well with old overgrown viburnums and roses.

My lawn and flower beds have become infested with a weed my neighbor calls yellow nutsedge. Do you know what this is and how it can be controlled?

Yes, yellow nutsedge is a common weed that can become invasive. It has yellow-green, grass-like leaves that grow from a triangular stem. It will grow to 18-30 inches in height.

The plant dies back to the ground each winter, but the roots are hardy, so it acts as a perennial and emerges from the ground each spring. If it is allowed to mature, it will develop and spread by seed. However, it spreads primarily by underground tubers or nutlets. If you pull up a clump, you will invariably see one or more of these white nutlets at the base of the stem.

I recommend that you try to control nutsedge by pulling it by hand. It is a persistent weed, so you will need to be even more persistent. You can also control it by spraying with an herbicide. You can call the Home and Garden Information Center at the number below for advice on what chemical to spray.


1. It may still be springtime, but the summer sun is upon us. Be sure to wear a wide-brimmed hat to protect you from the sun's rays when gardening.

2. Keep newly planted shrubs and trees watered through all dry spells of the spring, summer and fall. They will need your help until their roots get well established.

3. Do not delay planting your vegetable garden. All your summer crops should be planted by this time.

Dennis Bishop is an urban horticulture educator for the Baltimore office of the Maryland Cooperative Extension Services. If you have a gardening or pest problem, you can call the Home and Garden Information Center hot line (Monday through Friday, 8 a.m. to 1 p.m.) at 800-342-2507. You can also e-mail questions, order publications and diagnose plant problems by visiting the Web site www.hgic.umd.edu.

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