Important lawn care in the autumn
Did you know that northern grasses have two growth periods a year? All grasses begin to grow in the spring when the soil warms, but bluegrass, ryegrass, and various fescues get a head start on their southern cousins. They grow for a few months in the spring, until it gets really hot. And then, to protect themselves from the heat, they slow down or stop growing altogether. In warm years, that just means you don’t mow as much. In hot years, the whole lawn may be brown.
The second period of growth is the autumn. When the temperatures drop and the rain, fog and dew provide plenty of ambient moisture, grass greens up and starts growing again. The fall growth spurt isn’t as fast as the spring one, but it is crucial. Instead of putting all its energy into growing blades of grass, much of the energy produced will be stored in the crowns of the grass to prepare for winter dormancy.
Because the autumn growth is a period of energy storage, now is the most important time to fertilize a lawn. If you can only spread fertilizer once a year, early autumn is the time to do it. The grass will benefit immediately, but it will also store the nutrients for use next spring. After a long, hot summer like this has been, the grass will have experienced enormous stress. If you want to learn more about how to fertilize, visit ohioline.osu.edu/hyg-fact/4000/4006.html.
If you have a thick layer of woody, dead material between the green of your lawn and the ground, you may be having issues with thatch. A thin layer of thatch is normal in any lawn, but if the layer gets too thick it can begin to cause problems. If you have more than half an inch of thatch, one of the best ways to reduce the amount of thatch and improve the soil is called core aeration. This process pulls plugs of soil out and lays them on top of the lawn. This improves the drainage of the lawn and encourages the thatch layer to break down more effectively. If you’re considering aeration, fall is a great time. For more information on thatch, visit ohioline.osu.edu/hyg-fact/4000/4008.html.
Fall is also ideal for seeding cool-season grasses. The soil is still warm from the summer, but the air tends to be cool and moist. This makes it easier to create a seed bed that can stay consistently moist, but not too wet or too dry. Warmer soil temperatures will lead to faster seed germination. Once it germinates, grass needs about a month of good growing weather to get established so that it can survive the winter. In Delaware County, any seeding project is best done in the month of September.
The temperatures this summer were so high, for so long, and water was scarce. Much of our region had watering restrictions. This means that there are areas in many lawns that might not fully recover. If the areas that have not become green are larger than four inches across, it may be more practical to rake out the dead grass and re-seed the area. If the area is smaller, many varieties of cool-season grass, especially Kentucky bluegrass, will fill in the bare area. For more information about seeding a lawn, visit ohioline.osu.edu/b546/b546_6.html
The educational series scheduled to be held Sept. 20 at the YMCA has been cancelled. Please mark your calendars for Oct. 18 for the final session of the gardening series. Thank you for supporting our programs.
Wendy Wolpert is a Delaware County OSU Extension Master Gardener volunteer.