How to prepare your lawn for fall

It’s time for fall lawn care

Michael in Warrenton, Virginia, sends this timely email: “I know that fall is the best time to do lawn maintenance. What’s the correct order in which to do the following: top dressing with compost, aerating, and overseeding?”

You are correct, Michael. The perfect time to do all the things you mention is mid-August through mid-September; as soon as possible after the summer heat breaks and the soil is dry enough to work.

Don’t work when wet

That last part is very important: Never disturb wet soil, and never work heavy equipment on top of a wet lawn; it’ll ruin the structure of the soil you need in good shape to support your lawn long term.

So if you have an automatic watering system, turn it off. Mark the last day you got a decent rain on your calendar and then get prepared to get to work a week after that.

Step one: Pull the plug(s)

In his email, Michael asks: “What’s the correct order in which to do the following: top dressing with compost, aerating, and overseeding?”

The first step would be to do a core aeration to open up the compacted soil, which will then be much more receptive to seeding. Many lawns in our area were sown on nasty unimproved clay — and all of them have endured years of heavy mowers and foot traffic that have compacted the soil into something much more like concrete.

Rent (or even better, hire) a core aerator, which is a machine that pulls plugs out of the soil and really opens things up. (If you’re not handy with big machinery, this is a great job to farm out.)

Anytime over the next month is the perfect window to aerate a lawn. But you must actually remove plugs of soil to do any good — just poking holes in the turf without removing anything is a waste of time.

Be sure to wait until the soil is a dry as possible for best results. After you’re done, you can leave the pulled-out cores on the lawn (where they’ll fall apart after a few weeks and/or the first mowing) or rake them into a big pile and compost them — ideally with lots of shredded fall leaves.

Step two: Spread some black gold

We continue with Michael’s question: “What’s the correct order in which to do the following: top dressing with compost, aerating, and overseeding?”

Core aeration — pulling plugs out of the lawn to relieve soil compaction is the perfect first step, Michael.

Then spreading an inch of compost on the newly aerated lawn will provide a perfect fall feeding, dramatically improve the organic matter content of your soil, and provide a perfect seed bed for the final step of filling in bare spots with fresh seed. And it’s easy — just have a big load of compost delivered, shovel it into wheelbarrow loads, dump them out on the lawn and then use a rake to spread it all around as evenly as possible.

This isn’t rocket science and you have a lot of wiggle room with amounts. You’ll be amazed at how quickly the compost seems to just disappear. (Especially if you throw a spreading party with beer and barbecue waiting at the end; then the work will go really fast.)

And because this is a lawn (and not flowering/fruiting plants), you have a lot of compost options.

  • You can use finished yard-waste compost like Maryland’s great “LeafGro.”
  • You can use fully composted manure.
  • Or you can use aged (not hot and fresh) mushroom soil.

I would avoid top soil; it’s a meaningless term, and you won’t get near the level of organic manner that true compost, composted manure or mushroom soil brings to the table.

Now you can sow that seed

We finish up with Michael’s question: “What’s the correct order in which to do the following: top dressing with compost, aerating, and overseeding?”

Aerate first to relive soil compaction; dethatch as well if you have a lot of browned out stolons.

Then spread about an inch of compost over the entire lawn — or at least the parts you see and use the most. (If you have 5 acres, just work on the areas you actually use. The rest will do fine with a high cut and the clippings always left behind.)

Next, spread new seed to fill in bare spots. Just sow the seed by hand or in a spreader and gently rake it into that wonderful compost. Don’t put down straw or other nonsense — it limits the germination and looks awful for many months to come.

Then gently water the lawn for half an hour morning and night until the seed sprouts, which will be quick in this perfect weather. After it sprouts, cut back to morning only, and don’t water at all if we’re getting reliable rain.

Fall lawn care: Seed and/or feed

  • If you have a warm season lawn of zoysia or Bermuda grass, do nothing now. Your lawn care season is in the spring.
  • But, if like most in our region you have a cool season lawn of fescue, rye and or bluegrass, the next month is prime time to improve it or to start a brand-new lawn. Grass seed sown in the spring germinates poorly in the cold soil and then burns up in the summer heat. But the soil is now the perfect temperature for rapid germination, and the shorter days and cooler nights to come are ideal conditions for cool season grasses to establish themselves.
  • Don’t need to seed? Anytime over the next month is also the time to feed turf grass.
  • Compost is the ideal food; it provides all the nutrients your lawn needs and improves the structure of the soil. Can’t be beat.
  • Next best food is corn gluten meal — but don’t use corn gluten meal if you’re sowing fresh seed anytime soon. The natural pre-emergent activity of this organic fertilizer might inhibit some of the germination.
  • Bagged organic fertilizers labeled for use on lawns are also top notch. Hint — they’ll do an even better job if there’s also a little bit of compost on the lawn. (Spread fertilizer first, then the compost.)
  • If you must use old-school chemical lawn fertilizer, be sure to follow the new lawn care laws — that means a gentle amount of nitrogen, the first of the three “N-P-K” numbers on the label. Nothing over 9 is legal for lawns in Maryland or Virginia. (And high nitrogen fertilizers were never good for your grass. In fact, they’re the cause of a lot of brown dead lawns.)
  • And no phosphorus; your lawn doesn’t need it and the Bay sure can live without it.

Mike McGrath was Editor-in-Chief of ORGANIC GARDENING magazine from 1990 through 1997. He has been the host of the nationally syndicated Public Radio show “You Bet Your Garden” since 1998 and Garden Editor for WTOP since 1999. Send him your garden or pest control questions at MikeMcG@PTD.net.

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