So you want a better lawn next spring and summer. You want barefoot-enticing, carbon-sequestering, strike-envy-in-the-neighbors turf.
You’ve got to get to work this fall. But at least the weather is actually on your side.
That’s the dirty little secret of gardening in Colorado: Fall is better than spring for so many things, especially lawn work.
The majority of Colorado yards have cool-season grass lawns, including Kentucky bluegrass, tall fescue and perennial rye. And fall is the perfect time to put down new sod, new seed, or take a lawn that already looks decent from good to great.
“If you can only fertilize one time a year, fall is the best time,” says Toni Koski, Colorado State University professor and a regionally prominent turf expert. Plan on mid-September for that task.
And if you want to reseed a lawn that’s patchy, thin, wimpy, weedy or all of the above, “fall is a great time,” says Alison O’Connor, horticulture agent for the Larimer County office of Colorado State University Extension. “Soils stay warm until mid-November, so turf seed has that much longer to germinate.” Warm soils also help organic fertilizers’ microorganisms do their work, Koski adds.
Lawns with problems can benefit from what pros call lawn renovation, meaning the lawn needs help but you’re not going to lay down new sod. You don’t want to kill the old grass, but you do want to get a lot of new, young, strong seedlings established in this perfect fall window. (Got a warm-season, native grass lawn, such as buffalo grass or blue grama? Good for you. You’re off the hook as far as reseeding goes, as these grasses germinate in June.)
To renovate a cool-season lawn, you’ll combine three processes: aeration, overseeding and fertilization. Get on the phone — now — and schedule the aeration for early September — or set a date to rent an aerator. (Unless you’ve got a Sumo wrestler as a next-door neighbor and a dining-room table-sized yard, those lawn-aerating sandals won’t do the trick).
But before you poke holes in the lawn? Check your irrigation system. The overwhelming percentage of lawn problems O’Connor and Koski see, they said, are water or irrigation problems — uneven coverage, broken or tilted heads, all of it Luckily, sprinkler-system companies aren’t as busy in fall. Get repairs or adjustments done before you aerate — and plan your lawn renovation for a month before you have the sprinkler system blown out.
If your system is a hose and sprinkler — and come frost, that’s every homeowner — make good friends with it. You’ll be using that sprinkler a lot, so if it doesn’t provide even, consistent water, hit the sales for a new one. Rehang that hose caddy.
When you get down to aerating, “you can’t make too many holes,” O’Connor says. “Really Swiss-cheese the lawn; go in every direction. You may have to pay a little extra” if you’re having a service do it, but it’s worth it.
“The purpose of aerating is not just to make the soil better for existing grass,” O’Connor says. “The aeration holes make perfect little chambers for grass seed. They don’t dry out as fast. It’s heaven for a seed.”
Then reseed and fertilize the same day. Use your fertilizer spreader to put down seed; then use it to fertilize; then go over the lawn with the back side of a rake to knock seed into the holes. Then water everything in.
Warm soil and cool air means those seeds dry out more slowly, which means you won’t have to water them as often, but do try to keep them moist, which means daily watering, possibly twice daily.
Kentucky bluegrass will be the slowest to germinate (10 to 14 days); tall fescues next slowest (6-8); perennial ryes pop up in a mere 3 or 4 days. But all of these grass types (most bagged seed contains a blend) will germinate faster in fall than in spring.
As the grass germinates, mow the lawn normally — don’t lower the mower height, Koski says. “You’ll read you should mow your lawn shorter with the last mowing, but it’s totally incorrect. Just keep mowing until it stops growing.” This encourages the spread of the new seedlings, which is exactly what you want.
Can we say the “w” word? What about weeds?
Sorry, but you’ve got another chore that fall is perfect for: killing perennial weeds. Dandelions, bindweed, clover, thistles — all of these are storing energy in their tenacious roots. If you must use chemicals, hit these weeds now, Koski says. Try painting or dabbing, rather than spraying. More is not better. (If they have seed pods, deadhead first).
But annual weeds — crabgrass, chickweed, purslane — these will be gone soon anyway, killed by frost. Pull them by hand. Don’t use pre-emergent to do it, because such chemicals remain active for months, preventing new grass seeds from germinating as well as weed seeds. If you use it, do it in spring.
And O’Connor and Koski agree: The best defense against weeds is a thick, vigorous, healthy lawn.
Finally, your young lawn will need winter watering, just like the rest of your landscape. Koski recommends at least monthly, but it may need it more often depending on the weather — including precipitation, drying wind, and how hot or cold it gets — and the lawn’s exposure. There’s no substitute for sticking an old screwdriver into the soil in a couple of places to check turf moisture.
The good news: Winter watering your lawn waters your trees, as well.
Susan Clotfelter: 303-954-1078, sclotfelter@ denverpost.com or twitter.com/susandigsin
Raking leaves
Here’s one chore you can skip. “It’s fine to mulch tree leaves back into your lawn,” says Tony Koski, a turf expert at Colorado State University. “It doesn’t hurt the lawn, and there’s some research that says it actually helps the trees.”
“Leave the bag off your mower unless you have an extremely thick layer of leaves,” says Alison O’Connor, horticulture agent for the Larimer County office of CSU Extension. “Make multiple passes and chop them as fine as you can… You can put them around perennials as an extra layer of protection.”
Resodding
Fall is also a great time to lay down new sod. It will have more time and more consistent temperatures to get established. Just don’t wait too long to take advantage of cooler temperatures. October is too late.
Lawn removal
You’re going to do the right thing and change a STA — stupid turf area — into something water-smart.
Don’t go rent a sod-cutter. Koski says he understands those who want to avoid glyphosate herbicides, a.k.a Roundup. But removing turf, rather than killing it, ignores a fundamental condition of Colorado topsoil: There isn’t much of it.
“The deepest most sod-cutters can go is 2 inches. When you do that, you’re removing some of the best soil in your yard. If you go more shallow, you’re going to leave seeds and rhizomes in the soil,” meaning the grass will come back.
He suggests two passes with glyphosate, seven to 10 days apart. Then, till in the dead plants or plant right into them. Once it’s dead, the grass acts as a mulch itself. “Or you can bury it or pile newspapers on top of it. But I certainly wouldn’t remove it, because it’s really good soil and organic matter.”
