Q. What can I do to get rid of the moss in my lawn?
A. Moss indicates one or more of the following conditions: low soil pH (soil is too acidic); excessive shade; low soil fertility; and compacted or poorly drained soil. Call the number below to request a University of Maryland soil-test kit. The basic test costs $5 and will give you recommendations on liming and fertilizing the area. Rake out the moss while you're waiting for the soil-test results, and incorporate some leaf compost into the area. If the site is too shady to support turf grass, consider growing a shade-loving ground cover, like bugleweed, primrose, phlox, woodruff or lily of the valley.
Q. What can I do to prevent bottom rot on my tomatoes?
A. Blossom-end rot is caused by a lack of calcium in the enlarging fruits. Affected fruits develop a brown or black rot on the bottom. The condition occurs when tomato-plant roots cannot pick up enough calcium either because of low soil moisture or low calcium levels in the soil. Prevent this nutritional disorder by: keeping soil pH in the 6-7 range; deep, frequent watering; spreading organic mulches around plants; and avoiding high-nitrogen fertilizers like urea and ammonium nitrate. Also, when you transplant, mix a handful (about half a cup) of DTC finely ground lime with the soil from each planting hole.
Q. My lilacs bloomed beauti-fully this spring, but they're a bit overgrown. When and how should I prune them?
A. Lilacs should be pruned after the bloom period. First, remove faded and spent blossoms. Next, cut off the suckers emerging from the crown. Then remove weak, damaged and overcrowded shoots at the crown. Finally, prune out very old, thick trunks that no longer produce blooms. Avoid the temptation to trim the entire shrub back. That will remove the flower buds that will produce next year's blooms.
Garden tips are provided by the Home and Garden Information Center of the Cooperative Extension Service of the University of Maryland. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507 or visit its Web site at http://www.agnr.umd.edu/hgic.
This week's checklist
* Plant food to encourage butterflies to grow in your back yard. The caterpillars of swallowtails feed on parsley, fennel and dill, and monarchs feed on butterfly weed.
* Avoid rabbit damage in the vegetable garden by erecting a wire-mesh fence 3 feet high and extending several inches below ground level. Hot red pepper flakes sprinkled around vulnerable plants will also deter rabbits.
* Don't worry about spittlebugs, those small, frothy masses you may see on pines, shrubs, strawberries and perennials.
* Hill up potatoes to encourage tuber formation and prevent tuber exposure to sunlight. Continue to plant seed potatoes through July 4 for a succession of new potatoes.
Pub Date: 5/03/98