I pay very little attention to my lawn. My priorities are perennials, vegetables, trees and shrubs. I've often thought that if ever I were to rid my lawn of weeds, I wouldn't have anything left out there but an acre of red clay. As long as it comes up green and gets cut regularly, I consider my lawn respectable.

There are, however, many gardeners who fret over their lawns, and this month they may be able to do something about bare spots and weedy grass. While September is really the best time to tend the lawn, particularly if a major overhaul is called for, there's quite a bit you can do in April to prepare for summer's wear and tear.

You almost can't over-lime the lawn. In case you hadn't noticed by now, we have rather acid soil in this region, a condition that makes for great azaleas but not so great grass, which prefers neutral soil.

Some gardeners who have fireplaces undoubtedly disposed of ashes through the winter by spreading them on their lawns. That is very good for the grass, as long as the ashes are dead before theyre spread. But it takes a powerful lot of ashes to neutralize the acid soil hereabouts. Thus it may behoove you to pick up a bag or two of ground limestone and spread it at a rate of perhaps 35 pounds per 1,000 square feet. If you didn't spread ashes in the winter, add larger amounts of limestone, up to 50 pounds per 1,000 square feet. If your lawn needs quick help, apply hydrated lime -- it's absorbed more quickly than ordinary limestone.

If your lawn looks relatively good, you could almost stop there. You'd be amazed at how much an application of limestone can do to boost grass growth and health. If your lawn still isn't up to scratch, you may want to add fertilizer. Theory has it that adding fertilizer will make the grass grow rapidly and choke out slower- growing weeds. I've always found this hard to believe. If grass grows well in rich soil, then so must weeds. But I was quite surprised to find a short time ago that the theory works.

While I've sadly neglected my lawn, not so my fields. A few years ago I ordered 20 tons of chicken manure from the Perdue plant in Salisbury. The rotted manure was delivered in an enormous tractor-trailer and dumped in mountainous piles in the middle of the riding ring on the farm. From there we spread it with a rented front-end loader, which was great fun to negotiate until one tire went flat -- but that's another story. And of course, six acres of chicken manure is something the neighbors won't soon forget. The odor permeated kitchens half a mile away even a month later.

A local farmer disced the fields lightly, after which I top-seeded with a mixture of grasses. What had been a field full of weeds is now lush pasture virtually free of all weeds except pesky thistles, which are easy to spot and dig up individually.

Which brings me to the subject of fertilizers. If you can overcome the difficulty of obtaining, spreading and living with chicken manure for a couple of weeks, it's absolutely the greatest stuff in the world, pure and high in nitrogen.

But it is hard to ignore chicken manure's side effects. Organic fertilizers of any kind are the best, and someday soon, I'm confident, they'll become easier to get and cheaper to buy. In the meantime, if you can find and afford some bagged sheep manure, which is also high in nitrogen, or bagged cow manure, which is not quite as high in nitrogen and therefore won't go as far, get it and use it, at least on a small lawn. Bagged, dry manure, incidentally, is virtually odorless when spread on a lawn, and, in fact, remains odorless when it gets wet, if it's been worked into the ground a little.

If your lawn is large, if it doesn't abut your vegetable garden and your only practical alternative is chemical fertilizers, then I suppose it would be more of a disservice to the grass to not fertilize it at all than to apply commercial nitrogen. Pick a high- nitrogen fertilizer, such as 20-10-10 (the 20 being the nitrogen). And find a slow-release fertilizer for continuous feeding all season. (It will last only one season, unlike organic fertilizers, which will provide nutrition for years.)

There are prepared lawn "boosters" you can buy, but be wary of these -- many contain toxic weed killers dangerous to animals and small children who romp on the lawn. I don't believe in using herbicides of any kind and to apply them to a lawn is positively criminal. A good boost of fertilizer and lime will go a long way toward ridding your turf of weeds.

If you've got bare spots, scatter some compost, organic mulch or peat moss, in any combination or singly, just to loosen the soil -- which tends to become packed when bare. That will provide some basic nutrition for growing seeds. Scratch it in and water it -- although with the wet weather we've been having you probably won't need to water. At any rate, use a fair amount of peat, mulch or compost and work it in so that the color of the spot, once you're finished, is a nice rich brown. Smooth the whole mess out so there are no lumps and sprinkle your lawn seed over the spot fairly heavily, using a mixture of Kentucky bluegrass and fescue. The former is good in the sun, the latter in the shade, and both are perennial grasses. Rake the seeds in lightly and keep the area moist, a project which, at this time of the year, doubtless will be taken over by nature.

Keep the chickens, dogs and kids off the spot and if the weather doesn't get too hot, you'll see seeds sprouting in about a week. After just a little while, a green carpet will have formed and pretty soon you won't even know there was ever a bare spot. GYPSY-MOTH SPRAYING -- Montgomery County warns that gypsy- moth egg sacks have been sighted on about a thousand acres in the county, mostly in the Bethesda area, up from 70 infected acres at this time last year. The Maryland Department of Agriculture has proposed an aerial- spraying program to begin this month. Don't panic. The spray will be bacillus thuringiensis, a wonderful bacteria that affects young gypsy-moth caterpillars (and a number of other insects in their caterpillar stages). It's completely harmless to animals and humans and in fact "breaks down," if you will, in about 24 hours. The caterpillar actually must eat a treated leaf to be affected by the bacteria, which enters the insect's mid-gut. It paralyzes the gut and "cessation of feeding soon follows," according to county officials. It takes four to seven days for the caterpillars to die. The timing in the spray program is important because BT controls the caterpillars only while they're very young. As they get older, the insects develop a membrane that stops the bacteria from working. Larger aerial sprayings are scheduled in Frederick, Howard and Baltimore counties. A similar program is proposed for Fairfax, but, according to the county extension service there, egg-mass sightings have been far fewer and more isolated than in Maryland. GARDEN DIG -- The Laurel Archeological Survey has come up with an intriguing concept: "Did you ever think of gardening as an expedition in archeology? You never know what will be preserved below the surface of the soil, so you should be prepared to encounter the remains of the past every time you cultivate and disturb the soils." You're also creating your own site for future archeologists, Conrad J. Bladey, resident archeologist, points out. Your garden's "botanical occupants will be remembered by the traces of their indestructible pollen and traces of their root systems." If you want to learn more about this timeless twist in gardening, a course in "Archeology for the Layman" is being offered by the survey and the Maryland National Capital Parks and Planning Commission for six weeks beginning May 3. For more information, contact Conrad J. Bladey, P.O. Box 1118ice to the3, Laurel 20707 or call him at 301/776-2854. SPRING IN BLOOM DANDY DAFFODILS -- London Town Publik House and Gardens in Edgewater, Maryland, presents its annual daffodil show and competition this Saturday, 2 to 5, and Sunday, noon to 4. Admission includes a tour of the restored Publik House and adjoining gardens: adults $2.50, over-65s $2 and children $1. Call 301/956-4900. HOMES & GARDENS -- Tour seven McLean homes and gardens on April 23 from 10 to 5, one of 34 tours being presented as part of Virginia's 50th annual Historic Garden Week. Tickets are $8, including refreshments, and are available in advance from the Garden Club of Fairfax, 978-9282, or on the day of the tour at its starting point, St. John's Episcopal Church, 6715 Georgetown Pike..