I'm not a serious lawn guy. My motto? "If it's green and you can mow it, it's a lawn." But I recently filled in a few bare spots. This is a good time to sow seed.
Fall is much better than spring to plant seed, as the soil is warm and the seed will germinate more quickly. Not only that, annual weeds and crabgrass are less interested in germinating now — they seem to know that winter is coming, along with the cold weather that will kill them. As an added bonus, September is generally rainier than August, so you probably won't have to water your newly seeded areas as much.
To develop a thicker, richer lawn, you can over-seed the thin parts by spreading some seeds over existing lawn. Just scatter some compost over places that need it, scatter seed and then drag a lawn rake over the area upside down. That will mix the seed into soil. You can also spread a thin layer of compost over the seed afterwards. For large areas a roller will help press down the soil, getting good contact between seed and soil. To prevent the soil from drying out you can cover bare spots with a thin layer of straw or hay to shade it after planting.
Don't buy pure Kentucky bluegrass, thinking you'll get a premium lawn. Get a good mixture of grasses. The color and texture of bluegrass is preferred by some people, but it requires full sun and more fertilizer than other grasses. Furthermore, any monoculture — such as a pure stand of bluegrass — is more susceptible to attacks by insects and diseases. And don't get the cheapest seed you can find. Good quality grass seed costs more, but is better.
For a lawn that requires the least fertilizing and mowing, choose a "conservation mix". It will contain red fescue, some perennial ryegrass, a little Kentucky bluegrass and white clover. The fescue, in particular, is deep rooted and will survive drought and high foot traffic. Few pests will bother it. The white clover in the mix will add nitrogen naturally — so long as you add no herbicides, which will kill clover. This lawn will do okay even without adding fertilizers.
If you are fussy and want good lawn everywhere, don't expect to be able to plant just one type of grass seed everywhere on your property. If you have shade, buy a shade mix that is designed for shady areas.
I know that the "Weed-n-Feed" companies sell bags of stuff to promote good growth while keeping out weeds. You can have a better lawn, in my opinion, by spreading a little compost over your lawn each year. Just fling fine compost with a shovel and then spread it out with a lawn rake — a quarter to a half an inch is plenty.
Weeds? Keep the blades on the lawn mower at around three inches to help shade out weeds when they start up. But cut the lawn a little shorter the last two mowings before winter — that will reduce the chance of mold or mildew developing during wet times.
Acid rain is a reality here in New England, so unless you add limestone, the soil in your lawn will eventually get to the point where weeds grow better than grass. You can get your soil pH tested through your state's Extension Service or buy a kit at the garden center. The test will tell you how many pounds of limestone per thousand square feet of lawn — so brush up on your math skills.
Limestone is very slow to move through the soil, and adding it in the fall gives it time to work. If you can scratch limestone into the lawn with a rake and get it below the surface a little, it will be closer to the crown, or growing point, for both roots and leaves. If you buy "dolmitic" limestone it provides magnesium as well as calcium. "Calcitic" limestone does not have magnesium — a soil test will tell you whether you need magnesium or not.
I always use the mulcher attachment on my lawn mower in the fall to chop up the leaves. The attachment blocks the exit where the mower would normally spit out the clippings, so it chops everything more finely. I do rake up the bulk of the leaves, but the smallest bits stay on the lawn, adding organic matter and feeding the microorganisms in the soil — and making a healthier lawn.
Years ago I bought a couple of sheep to mow my lawn, and found that they were difficult to manage. I borrowed a portable electric fence to keep them out of the gardens, but they still managed to eat some flowers and inexplicably left parts of the lawn uneaten. Oh well, they did provide free fertilizer — and eventually lamb chops. Any way you look at it, a nice lawn takes some work.
Read Henry's recent blog post about deer ticks, the various diseases they cause and how to avoid getting sick. Go to https://dailyuv.com/gardeningguy. Henry is the author of four gardening books. His website is www.Gardening-Guy.com.