Fall is the ideal time to plant the cool-season grasses we most commonly use for lawns. These plants thrive in the cooler part of our growing season, putting on the most growth in spring and fall.
While spring offers similar cool temperatures and high amounts of rainfall, there is added weed pressure since dormant seeds are ready to germinate as weather warms. In fall, there is significantly less weed pressure but sometimes a much smaller planting window, so timing is important.
Considering the fact that many cool-season grass seeds sometimes take up to 10 days to germinate, our fall-planting window is closing fast.
Most years, a mid-August seeding is just about perfect, with the middle of September being about the latest you can directly seed grass with the expectation that it will put on enough growth prior to freezing temperatures and the end of the growing season.
Whether it’s your entire lawn or simply a few bare patches you plan to re-seed, site preparation is just as important as follow-up care after seeding. Undesirable weeds must be eliminated prior to planting new grass seed. Consider hand pulling or digging, tillage or use of an appropriately labeled herbicide to control established weeds.
I prefer the use of tillage for site preparation as it offers the opportunity to improve your soil with the incorporation of additional organic matter. Use a prepared soil mixture or simply add finished compost to the surface and till it into the soil profile.
As an additional benefit, uneven areas can easily be leveled with tillage, so this a good time to fix any low spots. It is important to eliminate low areas, if possible, since they can promote many common turf diseases.
Seed can simply be broadcast over the prepared planting site and lightly raked into the upper soil surface. A light mulching with clean straw is a great way to preserve some soil moisture and reduce harsh conditions on any hot days left in the fall. It also serves to keep loose soil in place as grass roots establish.
Keep the newly planted seedbed well moistened to ensure seed germination. As tiny, new seedlings emerge, it is critical to continue to supply adequate water to the seedbed. If natural rainfall is less than 1.5-2 inches per week, plan to water your new stand of grass. For the first few weeks of growth, ensure that the upper soil surface stays consistently moist, which may require frequent watering in smaller amounts.
Over time, favor less frequent and deeper watering (to establish a deeper root system) over smaller more frequent applications. At some point, natural rainfall will take over and eliminate the need for irrigation this fall.
I often get asked about my favorite type of grass to seed for lawns, and my answer usually is, “it depends”. For most situations, I prefer Kentucky bluegrass varieties because I really like the finer-textured leaf blades and deep green color. Kentucky bluegrass has worked best for me on sites with better soils and full sun.
However, I’ve often had better luck with establishment of fine fescue or turf-type tall fescue on harsh sites will poor soil conditions or a lot of shade. Regardless of your preference, it pays to plant a mixture of varieties or even species for the best chance of success. Most local garden centers sell a pre-made seed mix or can recommend their own custom seed mix, which may be best suited for our area.
Another option for a more sustainable lawn are “low-mow” or “no-mow” seed mixes. These interesting grass species tend to grow slower with bunch forming or creeping habits that require little or no mowing. This reduces our carbon footprint by requiring less inputs for establishment and maintenance of turf areas. These grass species are typically very drought of both drought and poor soil conditions, growing well in full sun to partial shade.
If you want to learn more about lawn-care issues in Illinois, including all the details for new grass establishment, check out Illinois Extension’s “LawnTalk” website at web.extension.illinois.edu/lawntalk.
Ryan Pankau is a horticulture educator with the UI Extension, serving Champaign, Ford, Iroquois and Vermilion counties. This column also appears on his ‘Garden Scoop’ blog at go.illinois.edu/GardenScoopBlog.