Carol with some Behnkes Best grass seed.
Horticulturist Carol Allen knows about lawns – in a former job she had to deal with millions of visitors trampling the National Mall, which fortunately none of us have to contend with. And NOW is the best time to fertilize and seed your lawns, so the audience for Carol’s talk at Behnkes was listening carefully and had lots of questions. Here’s Carol’s advice for fall lawn care.
Actually the best time to start your fall lawn care process was last month, but don’t worry – there’s still time if you get to it. Optimally, like next year, you’ll spend some time in August getting rid of your lawn weeds, so the weedy spots will be bare, ready to receive new seed.
Perennial weeds may need more than one application of a liquid herbicide – or just hand-pull them. Carol says liquid products give better weed-leaf coverage and are more effective than the granular types. They also act faster, and speed is what’s needed now – especially if you’re doing the weed control in September.
Annual weeds, too, can be removed by digging or by using an herbicide, though generally Carol recommends using as little of these products as possible, and she’s pretty darn organic-only herself. She doesn’t aim for golfcourse-perfect lawns – they require massive amounts of chemicals ARE they’re a lot of work to create and maintain.
Roundup is a nonselective weedkiller, which means it kills whatever it touches. It can be used in a total re-do when you have to kill everything, then start over, but NOT when you’re keeping any of your existing turfgrass. Even if you’re really careful, the neighboring grass blades will be killed - don’t learn that the hard way.
Renovate or Start over?
Lovely lawn, despite the geese!
In making this decision, use the 40-60 rule. Namely, if you have at least 40 percent coverage with healthy turfgrass, it’s fixable. If not, kill what’s there and start over with a new lawn. The new lawn may take two seasons to fill in completely and you will have a more difficult time controlling weeds, so renovate not replace, if you can.
Turf in Part-Shade
Turfgrasses love and in fact are dependent on sun, so if you choose a grass seed for sun, know that that means FULL sun. “Shade-tolerant” grass types love the sun, but are tolerant of a little shade. Too much shade combined with a little drought spells drying, patchy turf. (Kinda discouraging for anyone with shade over lawn, huh?) So really notice how much sun your lawn gets before choosing between the two types or the result is too much shade, you might just give up and grow something that’s NOT stressed by shade. Four to six hours of afternoon sun is required to produce an adequate lawn, so count the hours yours gets and get real. For sites that get only 3-4 hours a day, try a blend just for shade – and if it fares poorly, time to look for an alternative.
One short-term trick for improving your too-shady lawn if you have an event coming up and you’d like the place to look its best is to sow annual or perennial rye. In two weeks it’ll look great; a few weeks later the rye will have died but by then, your event will be over.
Best Turf Type for our Area
The best-adapted popular cool-season turf type for the Mid-Atlantic is tall fescue, which is what’s in the local brand Behnke Best. (Carol recommends the University of Maryland for details about the various trials they’ve done demonstrating the superior performance of tall fescue but in a nutshell, tall fescues give a fine blade that’s resistant to many turf problems.) The Shade blend of seed has a high percentage of hard fescues, which are more shade-tolerant but less tolerant of traffic, so they aren’t used on soccer fields (which thankfully aren’t shaded, so they don’t need shade blends, anyway).
If your soil has been heavily compacted and you have a lot of turf to treat, definitely rent a core aerator to open it up. If your soil is moderately compacted, or just a spot or two are badly compacted – maybe the corner everyone cuts across rather than staying on the sidewalk – you can just use a spading fork. Plunge it repeatedly in the ground, wiggle it back and forth a bit, and you’ve opened up holes 3-4 inches deep that are needed to correct compaction. Make a set of holes every few inches.
Either way you’ve created those 3-4-inch-deep holes in your soil, then top dress with a good compost product like Leafgro, so that it fills those holes. In fact, a nice one-quarter to three-eight-inch layer of Leafgro on top of the entire lawn is a great way to both feed your lawn and to improve the soil structure. Whether it’s needed every year or every two or three years depends on how compacted the soil is and other stress factors.
Sowing the Seed
Your guide to coverage should be to achieve the “salt and pepper on eggs” look, not a “sand on a beach” look.
Follow the instructions on the bag and remember that for overseeding an existing lawn, apply one-half the thickness recommended for new lawns. You’ll want thicker coverage in barer spots, of course.
After sowing, do a light watering by hand (best) or with a sprinkler (using the sprinkler only briefly). Just the surface needs to be wet, about one-fourth inch deep. Repeat this for the first 7-10 days – or in severe heat, longer. After the new grass blades have some roots and are a couple of inches tall (a couple of weeks or more), switch to deeper watering – an inch per week, or more in severe heat.
Raking the New Lawn
So, what if your new grass is being smothered by fallen leaves from the nearby oaks? And smother exactly what will happen, so get them off the new grass – but not by raking. This is a job for your leafblower, and a small electric one will do the job just fine.
So, if you have leaves anywhere near your lawn, the fallen-leaf problem is another reason to seed early – like this week – rather than waiting until later in the fall when the leaves are dropping like crazy.
Feeding your Lawn
Fall is the perfect time to feed your lawn because it’s when the nutrients go to root growth, not the fast top-growth that feeding would produce in the spring (which only causes you to have to mow more frequently). Carol recommends just one application of fertilizer every fall, and in some situations applying a top-dressing of Leafgro is an adequate substitute. It all depends on how much improvement your lawn needs.
If you’ve applied grass seed, wait until the new grass blades are 1-2″ tall before applying fertilizer or apply fertilizer before you seed.
Which to use? Well, to make sure we don’t pollute the Bay and kill the crabs there (among other critters), Maryland’s legislature has wisely limited the amount of phosphorus in regular lawn fertilizer. “Starter” fertilizers are allowed to have more phosphorus because new lawns really need the extra phosphorus; for older lawns, our soils have plenty of phosphorus already.
Carol’s favorite lawn fertilizer is Espoma’s Lawn Organic lawn Food, which is 40% water-insoluble nitrogen (WIN). That percentage is the all-important info to look at on any fertilizer label, she says, because it’s the water-soluble nutrients that can quickly run off into the Bay and that number needs to be low. High-WIN products tend to be more expensive, but remember, they’re less likely to hurt the Bay, and also be wasted, which lessens the cost-savings.
Another great all-organic product that’s high-WIN is Milorganite.
You can apply lawn fertilizers up until mid-October.
For more information, Carol recommends these articles from the University of Maryland:
Posted by Susan Harris.