Springtime Nears, and Thoughts Turn to Renewal

Spring is right around the corner, so it's time to answer your late-winter questions.

Q: When do I cut back hydrangeas? -- Ellen F.K.

A: I assume you have a bigleaf florist's hydrangea ( H. macrophylla) that forms large blue, red or pink globe-shaped flowers. This is the most common variety seen in the Washington area. If that is the case, prune after flowering, because florist's hydrangeas bloom from buds that formed last year. Flower buds are shiny green or brownish and are larger and plumper than leaf buds. There is one at the top of each flowering stem. Flower buds usually form along the entire stem, but only the uppermost flowers open because hydrangeas are apically dominant, meaning they focus their resources on opening the buds at the top of the stems. Prune them as little as possible.

The buds at the top of the flowering stems sometimes freeze and die in winter. Cut stems with dead terminal buds back to live wood. Do this now. Prune to about an inch above a flowering bud. Remove dead canes. Cut about one-third of the shrub's thickest, oldest canes to the ground, selectively pruning one at a time. This will renew the hydrangea over a period of three years without sacrificing flowering value. If you need to make the shrub smaller, you can cut the plant in half, but this might sacrifice some of the blossoms.

I have several cherry laurels that were planted about nine years ago. They are overgrown. How should I prune them? -- Jim B.

After they flower and you enjoy their fragrance, shear hard. They will renew in a season. Retain some of the foliage, and the plants will regenerate faster. Prune so the shrubs are wider on the bottom than the top, so sunlight reaches them evenly. If you selectively prune them, shaping one branch at a time, they will regrow with a natural form.

Can you recommend a book or Web site for my area? I live in Frederick County, and I want to use plants native to this area if possible. -- Craig

The Maryland Cooperative Extension service (Contact: 800-342-2507, http://www.hgic.umd.edu) is a good resource. Two other sources of information are the Maryland Native Plant Society ( http://www.mdflora.org) and the Alliance for the Chesapeake Bay ( http://www.alliancechesbay.org/pubs.cfm). All have information on native Maryland plants, including those specific to Frederick County.

Do you have any tips for dealing with wild onions or strawberries? -- Al O.

Wild onion, also called wild garlic, grows in spring or fall and can be dug out with a weed digger. You probably won't get all the bulbs. Treat regrowth with a lawn weedkiller. I have successfully used Weed-B-Gon Lawn Weed Killer as a spot treatment, but don't spray the entire lawn or use it near bodies of water.

What you think are wild strawberries, which are edible, are more likely to be wild cinquefoil, which aren't. To recognize them, look at the flowers: cinquefoil flowers are yellow; wild strawberry flowers are white.

There is no selective control for wild cinquefoil, so you must pull them by hand. You can also use Roundup or another glyphosate herbicide, but it will kill all actively growing vegetation and shouldn't be used near bodies of water.