By Scott Aker
Special to The Washington Post
Thursday, June 8, 2000; Page H11
Q: Seeing beautiful mountain laurel in the woods has inspired us to plant more in our garden, but we know it is difficult to grow. I have three new plants ready to go in. Any suggestions?
A: The key to success with mountain laurel is establishment. The sharp differences between the soil in your garden and the light mixture in the pot mean that the plant will need help adapting. When you plant, tease the soil away from the outer portion of the root ball.
Mix this soil with the native soil in the planting hole. Set the plant a few inches higher than the surrounding soil, and add loose, organic garden soil around the outer edges of the root ball, being careful not to smother the top of the root ball with fresh soil.
Water the plant thoroughly, adding more soil to pockets of dirt that then have sunken.
Mulch your mountain laurel with pine bark to a depth of no more than two inches. Use shredded oak leaves or pine needles. Don't use shredded hardwood mulch; it sweetens the soil as it decomposes (mountain laurels like acid soil). You also can fertilize with a nutrient formulated to acidify the soil. Keep the roots evenly moist for the first two seasons: Check often; don't rely on rainfall.
The three things that kill newly planted mountain laurels are drought, soggy soil and black vine weevils. Mountain laurels are extremely drought tolerant, but they can't tolerate extreme drought until their roots have grown, usually two years after planting. The fine roots rot easily and will surely die if planted in heavy, sticky soil or if planted too deeply.
Black vine weevils are flightless insects that chew notches in the margins of the leaves as adults. As larvae, they feed on the roots. Because they cannot fly, they stay with the same plant year after year, or move slowly to azaleas, rhododendrons and mountain laurels nearby.
When selecting a plant from the nursery, look for telltale notches on the leaves. When you plant it, look carefully for small white grubs that are about the size of fat grains of rice. Any infested plant should be returned to the nursery where you bought it for a refund.
Q: We have been in our house for three years. Last year, a very old tree started producing "cotton." The tree is taller than our house and was totally covered with pods that eventually opened up and blew all over our neighborhood. Our yards were totally covered and so were our neighbors' lawns. A local nursery identified the tree as a cottonwood. Short of cutting the tree down, do you have any recommendations? Please help--this was extremely embarrassing last year and I don't want to repeat it.
A: Although it may not produce a heavy crop of seeds every year, it will always have the potential to do so. If you like the tree, I see no problem with keeping it. The cottony seeds are produced for two weeks, at most. Although some may germinate in lawns and flower beds, they are quite easy to pull up and are not a horticultural calamity equal to dandelions, ground ivy or wiregrass.
Q: Our asparagus bed has been in for about 10 years and has done quite well. The past couple of years, we have been getting a lot of thin stalks. This year, has been particularly bad. In the past, I have picked all stalks, thin or fat. This year, I am leaving some of the thinner stalks. Did the drought last year affect the bed? I have put fertilizer, compost, lime and mulch on the bed each year and have kept the weeds out of it. Is there anything I can do to get more larger stalks?
A: The plants are asking you to stop wholesale harvesting by producing progressively thinner shoots. Do not take stalks that are thinner than a pencil when they emerge from the ground. Consider forgoing any harvest next spring to allow the asparagus to build up some energy. Asparagus is very drought tolerant, but if your bed is weak from overharvesting, irrigate every two weeks or so during dry spells this summer.
Scott Aker is a horticulturist at the U.S. National Arboretum.
Have a question about gardening? Write Digging In, Home Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or e-mail firstname.lastname@example.org.
TIP OF THE WEEK
REMOVE FADING ROSE BLOSSOMS to promote a new flush of buds. Water roses during dry spells, but avoid getting leaves wet, especially in the evening. Use a granular, slow-release fertilizer formulated for roses.
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