It’s the middle of October, and plenty of lawns around the Des Moines metro still look thin. Maybe summer got away from you. Maybe the plan was to seed in September and the month filled up. We hear this every fall, and the honest answer is more useful than a sales pitch.
Here’s where the calendar stands, what Iowa State University Extension says about it, and how we’d handle a thin lawn right now.
Where the seeding calendar stands
Iowa State Extension names mid-August to mid-September as the best time to establish a lawn from seed. Its turfgrass specialists say seeding can generally run as late as the end of September. They also say October seeding can work, but the chance of success goes down each day after October 1.
An Extension article published on October 9 puts the recommended fall window at August 15 through September 30. It calls late October and early November the problem range, because seed can germinate but won’t mature before winter.
So we’re past the best window. That doesn’t mean you’re out of options. It means the choice depends on your yard.
Why fall beats spring in the first place
Cool-season grasses, the bluegrass and fescue in most Iowa lawns, germinate quickly in the warm soil of late summer. Warm days and cool nights keep them growing. Few weed seeds germinate in fall, so new grass has little competition.
Spring is different. Iowa State notes that lawns seeded in spring are often infested with annual weeds unless you take preventive steps. That’s why we steer people toward fall, and why missing the window stings.
Your options in mid-October
Overseed a thin lawn, with realistic expectations. If the lawn is thin but not bare, a late seeding still has a chance. The odds are dropping every day, though, and we’d tell you that up front. Seeding right after core aeration helps, because the open plug holes give seed a place to land. Iowa State calls early September the best time to aerate, so October isn’t ideal. We run aeration into late October when the ground cooperates. After that, it’s worth waiting for next fall.
Lay sod. Iowa State lists September and October among the best times to install sod in Iowa, and says sod can go in from spring through fall. Sod also holds slopes that seed washes off of. We recommend keeping traffic off new sod for 2 to 3 weeks. If you need usable grass before winter, or your yard has a slope, sod is often the better fit for the calendar.
Wait for dormant seeding, but not yet. Dormant seeding means sowing after turf growth has stopped and before the ground freezes. Iowa State puts that in late November through early or mid-December in many years. Air temperatures should stay low, and soil temperatures should be 40 degrees Fahrenheit or lower, so the seed doesn’t germinate before winter. The seed sits through the cold and starts in spring.
Dormant seeding has real downsides. A warm spell can trigger germination and a cold snap can kill the seedlings. Seed on the surface can wash away, rot in waterlogged soil, or get eaten by birds. You may need to overseed again in spring. Please don’t spread seed in October and call it dormant seeding. It’s too early, and the seed can still germinate.
What to do this month either way
- Keep mowing until the grass stops growing. Bluegrass stops growing when daytime highs stay below 50 degrees. In Iowa that’s usually late October or early November.
- Deal with the leaves. A thick layer of leaves left on the lawn can damage or kill the grass underneath and leave dead patches that weeds move into. Mow them into small pieces with a mulching mower, or rake and compost them.
- Think about late fall fertilizer. The grass stops growing above ground, but the roots keep taking up nutrients. Iowa State recommends an application in late October or early November to help root growth and spring green-up.
- Keep new seed damp. If you do seed, keep the top inch of soil moist. Seed of most lawn grasses germinates in 2 to 3 weeks when the seedbed stays evenly moist. For a new seeding, we recommend keeping traffic off for 4 to 5 weeks.
Mark next year’s date now
Iowa State’s turfgrass blog picks August 15 as the target date for seeding. Put it on your calendar. If you want a thicker lawn next year, a late-summer plan beats an October scramble every time.
Heavy shade and slopes change the plan, too. Both are hard on new grass, and we’d rather talk through them before you spend money on seed.
Not sure which option fits your yard?
We build and care for lawns across the Des Moines metro, including Ankeny, Johnston, Urbandale, West Des Moines, Waukee, Clive, Altoona, Norwalk and Bondurant. Read more about our lawn seeding, sod installation and lawn aeration work, or see how fall seeding timing works in our earlier post on the best time to seed a lawn in Iowa.
If you’d like us to look at your lawn and tell you straight what makes sense this fall, call us at 515-809-0690 or send a note through our contact page.