Cooler weather and dewy mornings of September awaken turf from hot-weather dormancy that began in late July or early August. New growth means changes in lawn maintenance as your turf is preparing for winter dormancy. You’ll want to troubleshoot and repair bare spots, fertilize, mow, and water appropriately for the cooler and more variable weather of fall.
Troubleshooting the bare spots in the lawn will involve mostly surveying the area. Take note of the increase in shade, change in soil moisture, and the density of the bare spots. Most likely the lawn is thin from the stress of a hot summer and over-seeding can be a simple and cheap solution. (Tip: seed should be covered with peat or light compost to hold moisture in and keep birds away.) Bursts of tree growth can reduce sun exposure and soil moisture so you will want to have supplemental watering and a shady seed mix if you come across these conditions. (Tip: if the tree roots have made it impossible to grow grass, consider turf alternatives such as astroturf, mulch, or hardscaping.
The lawn should be fertilized monthly between September and October with a high nitrogen fertilizer specifically designed for lawns. Doing so early on in September and October will encourage a fresh greening up and strong root development just in time for the grass blades to harden off. It will also make the grass much stronger so to survive the harsh winter to come. In November spread corn gluten as a weed suppressor. The corn gluten will suppress the new weed seed germination in any bare spots in the spring.
September and October can be hot, dry, and windy so be sure to keep your lawn watered in between major dry spells. Aim for 1” per week when watering your lawn – about the depth of a tuna can. If the lawn doesn’t get sufficient water, any seed and fertilizer you put down will have been a waste of time.
Lastly, your lawn will need regular mowing again. You may have reduced your lawn mowing frequency in the summer when it was dormant. Resuming a weekly or bi-weekly mowing will keep it healthy. Set your mower blade to 2” – 2 1/2” setting. Taller grass makes for a thicker healthier lawn.
One more fall maintenance task you may need to consider is aeration. This process is done by a machine that puts gaps in the soil to allow better air and water flow among the root systems of the turf. Fall is the better time of the year to have this done because it is drier and weed seeds are less prevalent. This is recommended for tough, hard, compacted soil in which grass has difficulties growing.