Fall Lawn Renovation
For cool-season lawns, fall is the time to renovate and improve. Fall lawn renovation can mean completely starting over, patching bare spots, overseeding to thicken the turf, changing the grade and re-planting, or a combination of the above. For the best results, you need to re-seed the new lawn grass before extended periods of frost hit. September is the ideal time for most cool-season lawn areas.
Warm-season lawns should be re-sodded or overseeded from March through July. The fall is not an ideal time for warm-season lawns to be renovated, as the grass types in these areas start to go dormant when the weather cools off.
Changing the grade
If your lawn slopes toward the house (funneling water toward your house) or is too steep, leading to erosion, changing the grade can help. You can kill your existing grass, or, if you have a steep re-grade involving adding a lot of additional soil (6 inches or more), you can simply establish the angle of the grade and spread the new soil on top. To establish the new grade line, tie a piece of twine to a fixed point at the top of the hill. Run the twine in a taut line to the other end of the property that needs to be graded. Use a stake to anchor the line and tie the line to the stake so that the line forms the desired angle for the new grade. Then, fill in so that the soil meets the line along its entire length.
Filling in or adding a new grass type
If the lawn is thinning and weak, overseeding with the same or a complimentary grass type can improve it. Mow the lawn as short as possible without scalping it. Then spread a ¼ to ½ inch layer of compost over the grass. Use a rotary or drop spreader to spread the grass seed. Then water the new grass seed twice a day for the first week, once a day for the second week, and every other day until it starts filling in. You must keep the grass seed consistently moist in order for it to sprout.
Starting from scratch
If you want to re-plant your cool season lawn with an entirely new type of grass, or you want to start over because the turf is too weedy, lawn renovation is the way to go. August and September are the best months for full lawn renovation, because the grass has a chance to re-establish. In transitional areas with cool-season lawns, you can push renovation into October, but only if you plan to plant cool-season grass.
Start by killing all of the existing grass with a non-selective systemic herbicide. (This is a herbicide that kills everything.) These herbicides work the best on actively growing grass, so irrigate and “baby” your grass before you kill it. (That sounds sad, but it works!) Once the grass and weeds have been eliminated, rototill to break up the top layer of the grass and soil. Then add at least one to two inches of a compost and topsoil blend. Use a drop or rotary spreader to spread the grass seed and then water according to instructions above. You can mow the new grass once it reaches 3 inches in height.