Mountain laurel thrives in parkland but struggles in urban landscape


I have seen mountain laurel growing in our state parks. Is it a native plant and will it grow well in home landscapes?

Mountain laurel (Kalmia latifolia) is native to eastern North America. In more northern areas, it will apparently grow well in full sun. But in our area, it grows best in partial shade. It is very common on the hillsides of our state parks and is especially abundant at higher elevations. In contrast, it does not seem to grow well in home landscapes. I have seen very few quality plants in Baltimore, and gardeners have commented that it is difficult to grow here.

I think this is related to soil. Our urban soils tend to be very heavy and poorly drained. Also, many of our soils have a pH that is near neutral or only slightly acidic. Mountain laurel must have well-drained, acidic soil with a pH of 5.5 or below.

While rhododendrons and azaleas have similar requirements, they seem to be more adaptable. If you were looking for a flowering evergreen plant, I would recommend one of these rather than the mountain laurel.

We planted a boxwood hedge along our front walk last spring. It looked fine through the fall, but this winter the plants began to turn yellow-green. What would cause this problem?

Some boxwood (Buxus spp.) varieties maintain a good dark green color through the winter months, while others naturally lose color. When the loss of color is natural, it typically affects the whole plant. If the entire hedge were discolored, I would guess that the cause is natural and that the color will return in the spring when plant growth resumes.

On the other hand, boxwoods are subject to several diseases that will also discolor the foliage. Diseases will often show up in one portion of the plant before others. If your plants are losing color and dying one branch at a time, I would suspect disease.

The other clue here is that the problem started in the winter. This indicates that the cause is natural.


1. It's time to start the vegetable garden. Spring crops such as peas, lettuce, cabbage and carrots can be planted.

2. Bagworms can destroy evergreen trees and shrubs in the summer. To prevent damage, be sure to remove and destroy all bagworm bags before the new eggs hatch in the spring.

3. Prune rose bushes back to healthy wood. Spread a thin film of white glue on the pruning cuts to prevent entry by cane borers.

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.

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