(As stated in previous lawn posts here, these tips are based on my experience alone. I offer no illusions of formal turf training or professional experience. This is solely what seems to work for me and my Southeast Pennsylvania lawn. Always proceed with caution and be mindful of conditions in your specific region.)
Few lawns in the mid-Atlantic region of the good ol’ US of A survive the summer unscathed, unless they are blessed with an in-ground irrigation system or a bountiful canopy of shady trees. Mine has neither. So every September consists of efforts at lawn recovery from another long, hot summer.
Even with adequate rain, exposure to the summer sun and heat will cause brown and dead spots, usually in the same areas of the lawn year-after-year. My trouble spots are concentrated along the eastern and southern exposures where the sun stays high in the summer sky for most of the day. Each year I try to mitigate the damage; but regardless of what tricks I use, I have to repair sun and heat damage to the usual areas every September.
This is the best time of the Summer/Fall season to fix what the sun has wrought. Any repairs taken now will give your lawn 8-10 weeks of Fall growing season, and a head start in the Spring. I normally begin this effort over the Labor Day weekend. Warm temperatures in the day and cool, dewy nights during September makes this an ideal time to regenerate growth.
Remove browned dead grass: An obvious problem is how to grow new grass with all that dead, matted grass in the way. There are two ways of approaching this problem, depending on the size of the affected areas. In my case I usually end up with one or two manageable patches of dead grass with other small patches spread throughout the lawn. For me, the more practical solution is a good dethatching rake.
No human looks forward to raking in any way, shape or form; and as a warning, dethatching is probably the most physically demanding raking activity known to man! So take your time and take care to rake lightly along the top of the lawn to minimize damage to healthy lawn plants and to the roots that remain from the dead grass you are removing. Even roots from dead growth can regenerate if deep enough to escape the worst effects of sun and heat. (For this reason, I suggest leaving dead, brown grass in place during the hottest summer weather. I believe it provides some cover from excessive heat for salvageable grass roots.)
Concentrate on small areas; pulls towards yourself, then rake forward to remove the dead growth from the rake tines. Work “up” the dead spot as dead growth will be dumped closer to your feet as you move along.
Do not fret the removal of some green growth. It’s inevitable given the technique and tools. As long as you’re not pulling up healthy roots, any green growth removed will grow back.
Now if you have large areas or – Heaven forbid – an entire lawn in summer shock, you can rent a dethatching machine (a.k.a. lawn comb) from an equipment rental store. The lawn comb makes much easier work of dethatching; and it’s not a bad idea to dethatch your entire lawn every couple of years. Dethatching will not only remove topside dead growth, but also that underlying layer of dead growth from seasons past as well as any accumulation of dead leaves, twigs and other debris. (I dethatched my entire lawn with a machine last September, and the results this Spring were impressive!)
The combing action of the machine version also does a nice job of disturbing the top layer of soil that makes over-seeding a bit more effective. Save yourself unnecessary clean-up raking by using your lawn mower with bagging attachment to remove the dead growth pulled up by either the dethatching rake or the lawn comber.
To seed or not to seed, that is the question! Generally, I do not over-seed, unless I’m doing the entire lawn every few years as mentioned above. Instead I prefer to let nature take its course, since I consider my lawn’s root system to be healthy enough to regenerate growth on its own.
Weaker lawns should definitely be over-seeded. If you decide to seed and live near me (southeastern Pennsylvania), try to avoid Kentucky blue grass and Bermuda seed in favor of a rye and fescue mix. In my experience, neither blue grasses nor Bermudas tolerate the mid-Atlantic summers very well.
If you apply seed, I suggest an application of starter fertilizer which will give the entire lawn a more concentrated boost that a weed ‘n feed. REMEMBER: Never apply a weed ‘n feed to freshly seeded grass. The “weed” component of a weed ‘n feed will inhibit the germination of any new seed. Generally, you must wait six weeks after a seeding to apply a weed ‘n feed product.
Fertilize: Covered fairly well above. Just let me reiterate … Starter fertilizer for either seeded or unseeded lawns. A starter fertilizer will work regardless of whether you are seeding or not. Weed ‘n feed not only fertilizes but also gives you a leg up on maintaining momentum against weed incursions the following Spring/Summer. (I prefer to apply an extra weed ‘n feed application in September. It will give my lawn a nice jolt going into Indian Summer, and it maintains the momentum of anti-weed efforts taken in the Spring.)
One side effect of any fertilization at this time of the year is that you should plan to be mowing well into November. But a thick, healthy lawn is worth it, right?!?
Watering: Don’t forget to water! Keep an eye on your forecast; and make sure your lawn gets a sufficient watering, especially if you face a hot September and little rain. An astute observer will also pay attention to the presence of dew on the lawn in the morning during late summer and early fall. Warm daytime temperatures, followed by cool evenings can provide heavy dews that act to essentially self-water the lawn. If you pay attention to these condition, you can better gauge whether watering the lawn is really necessary. When in doubt, get the hose out!
Aeration: If you did not aerate in the Spring, doing so in the Fall is a good alternative. Some lawn aficionados will aerate in both the Spring and Fall! I don’t. But if you are faced with hard-packed soil, or your lawn gets a lot of foot traffic, aerating twice a year could be beneficial.
Leaves: Once the leaves fall from the trees, make sure you get them off your lawn as best you can. Allowing leaves to cover your lawn over the Winter will exacerbate a number of problems, and can block early Spring growth. (I have but one small cherry tree on my property, yet I get a thick covering of leaves from HUGE trees in neighboring yards. I love the trees and the shade they provide our backyard in the summer, so I deal with the fallout begrudgingly. My sole concession to my inherent desire to avoid unnecessary work is my refusal to undertake my final leaf roundup until every tree around my property has lost every single leaf, hoping in the meantime for windy weather favorable to blowing said leave into someone else’s yard!)
Winterize: Yes, this is another form of fertilization. But since it’s done separately from your lawn recovery efforts, I treat it separately here. Winterizing fertilizers are applied in the Fall, usually between Halloween and Thanksgiving. The nutrients delivered by a winter fertilizer are stored in the grass’ root system, and provides a nourishment to your lawn in the early Spring. It should be applied before the lawn goes dormant for the Winter.