EVERYONE LIKES a nice lawn. Some folks obsess over lawns. Others, like me, figure that if it’s green and you can mow, it’s a lawn. Either way, this is the time to do a little lawn care if your lawn needs to be thicker or if there are bare spots where the dog buried a bone. Annual weeds are losing their pep. Warm soil temperatures and fall rains make starting some new grass easier.

I recently spoke to Paul Sachs, owner of North Country Organics in Bradford, Vermont. He is my go-to guy whenever I have lawn questions as he has studied and written about lawns for decades. He confirmed much of what I knew – and, as always taught me more about lawns.

Paul said that this is the time to increase the plant density in your lawn by overseeding. Overseeding is the process whereby you scratch up the surface of the lawn with a rake and spread some good lawn seed. He recommends adding a quarter to half an inch of mature compost at the same time. Mature compost does not smell bad, he said, and is not hot in the pile. Earthworms in the pile are my indicator or a mature compost. Paul also recommends spreading some Pro-Start, an organic fertilizer made to be spread when planting seed. It is a 2-3-3 fertilizer that will encourage good root growth without pushing too much top growth.

Ground Ivy By over-seeding now your grass plants will get their roots established when annual weeds are declining in vigor and are less competitive for water and nutrients. The best time to do this is from the end of August until mid-October. Once a hard frost hits, the top growth will stop, Paul Sachs said, but root growth will continue if plants have been established. And when you buy seed, don’t get the bargain mix. Get a good blend with several different kinds of seed, and little or no annual grass seed. The annual seeds start quickly, but die at the end of the season. Read the label, and pay more for a good lawn seed.

The Lawn Guys who mow for a living often recommend coreaerating for compacted lawns. Paul Sachs has an easy test for compaction: take an ordinary screwdriver and try to push it 4- 5 inches into the lawn. You should be able to do this without struggling. If the lawn fails the screwdriver test and you want a better lawn, rent a core-aerator or call in an expert. These machines punch 3/8 inch holes in the lawn. You can then topdress with compost to get more organic matter into the soil and add some organic fertilizer at the same time. If you are not overseeding, just aerating, use an organic fertilizer with higher numbers such as Pro-Gro, a 5- 3-4.

Compaction makes lawns whimper and moan. If you walk from your car to the front door every day, cutting across the lawn, you are compacting it – and that is where you will get weeds. Crabgrass and dandelions do better than grass in compacted soils, and out-compete the lawn.

Paul told me that dandelions can be useful weeds. He said that they are most common in compacted soils, and serve a purpose: they loosen it up and attract earthworms and phosphorous solubilizing bacteria – bacteria that can process the mineral form of phosphorous and make it available to grass. Dandelions help to penetrate hard pan, and if you have enough of them, they can improve drainage. Many dandelions are biennials, though some plants may live several years.

I asked Paul about crabgrass and ground ivy. He said the best weapon is not herbicide, but good soil and a thick, lush lawn that is left tall – the taller the better. Crabgrass will turn purple soon, he said, and spread this year’s seeds. But if you overseed, your lawn can compete nicely with the crabgrass – particularly if you keep the blade up as high as it will go. Get the grass established now, and it will start off faster in the spring and choke out the crabgrass.

Ground ivy (Glechoma hederacea), also known as Creeping Charlie (or Jenny), Lizzie-Run- Up-the-Hedge, Blue Runner, Alehoof, Field Balm, Cat’s Foot, Runaway Robin or – and this is the best – Rat’s Mouth, is an intruder in my lawn (and probably yours). Paul said you can beat it without herbicides if you really want to, but it might take a year. Rip it up with a rake as much as possible and overseed the lawn now. In the spring, give the lawn a dose-and-a half of Pro-Gro – 30 pounds per 1,000 sq ft. Put the mower blade up as high as it will go, and then give it another 30 pounds of organic fertilizer a month later.

I’m a pretty industrious gardener, but I’ll have to admit that I am not going to try to eliminate my ground ivy. Nor my dandelions. I love dandelions: they’re bright and cheerful - and free. I like to think of benevolent lawn fairies sprinkling dandelion seeds about, giving me all the benefits of daffodils in the spring, and more. After all, wouldn’t you pay a fortune for daffodils that multiplied and rebloomed in the lawn after mowing? What’s not to like?

Henry Homeyer is a garden designer living in Cornish Flat, NH. His Web site is www.Gardening Guy.com.