Jennifer Schultz Nelson
Extension Educator, Horticulture
Though the growing season is beginning to wind down, this is in fact the best time of year to give your lawn some extra attention that will help improve the quality of your lawn well into next year.
I'll admit the lawn is just not my top priority. I would rather spend my gardening time with my flower and vegetable gardens. My husband Chris argued with me about the size of our gardens when we first bought our home because he wanted "lots of lawn to mow". Three years down the road, he's wondering about his sanity when he made that statement.
The Nelson household is not a great example of intensive lawn management. We are pretty middle of the road in our lawn care. We will not be winning any "green grass awards" any time soon, but we do try to keep our lawn healthy with appropriate fertilizers and aeration.
The grasses typically grown in many lawns are cool season grasses, like Kentucky bluegrasses, perennial ryegrasses and fescues. They grow best in cool spring and fall temperatures, and turn brown and go dormant during the heat of the summer if not watered.
Less common locally are lawns composed of warm season grasses, like zoysia. These grasses do their best growing in the heat of the summer, and are brown and dormant in the spring and fall.
Most lawns in our area are composed of cool season grasses. If you are looking to start a new lawn or renovate your existing lawn, fall is the best time to do so. The primary reason is that not only is the lawn actively growing in the cool fall temperatures, but the soil is thoroughly warm.
Although air temperatures may be in a good range for grass to grow in the spring, the soil warms considerably slower. Grass seed sitting in cold soil will not grow very quickly even if the air is just right. The longer seed sits in cold, often wet soil, the more likely it is to rot. In fall, soil and air are both just right for seed germination.
Whether you are seeding a new lawn or overseeding an existing lawn to fill in some thin or bare spots, it is crucial that the grass seed has good soil contact. If you just scatter seed on top of existing turf, it is very likely that the seed will just sit on top of the grass or thatch and not touch soil. Without soil contact, the seed will not germinate. Use a garden rake to scratch the seed into the soil after broadcasting seed.
If you are seeding a large area, it may be worth your time and effort to rent a slit seeder, which is essentially a machine that makes little slits in the soil beneath your lawn and drops seed directly into these slits. My husband had difficultly getting anything but weeds to grow on the lot we purchased next door to our home until he used a slit seeder. Good soil contact made all the difference in getting grass to grow over there.
Fall is also a great time to aerate your lawn. Aerating loosens up compacted soil, and helps break down thatch. You may not notice compaction at first. Last summer we noticed a patch of lawn that just slowly went from bad to worse. We couldn't figure out why this spot was worse than the rest of the yard.
Then is occurred to us that this was where our big 4th of July party has been the last three years. Lots of lawn chairs and foot traffic does a great job of compacting the soil. We've also noticed a lot of weeds popping up in this area that grow well in compacted soil, like spurge.
There are aerating devices out there that are just spikes that stick into the ground, but aeration is best done with mechanical devices that remove plugs of turf and soil from the lawn and deposit them on the surface. Actual removal of a plug is crucial to the breakdown of thatch.
Thatch is dead stems, roots and nodes of turf grass that do not break down readily. Bringing some of the soil to the surface through aeration exposes the thatch to microbes in the soil that will break down the thatch more quickly.
A common homeowner myth is that leaving grass clippings on your lawn will cause thatch. This is simply not true. Clippings are 75-85% water and decompose readily. If anything is to blame for thatch, it's over-fertilizing. Pushing too much top growth of turf creates a situation where the plant cannot support all that green growth and it dies. Then the homeowner puts on more fertilizer because they think the lawn is not as plush and green as it should be, and the cycle begins again. The dead plant parts create thatch. If thatch gets thick enough, it can prevent the lawns roots from reaching the soil.
Fertilizing turf may actually be more important in the fall. Fertilizing in the fall helps the turf recover from a stressful summer, and a stress-free plant is more likely to survive the winter undamaged. Fall fertilization promotes turf root growth, and turf with a good root system will be well-equipped to survive times of drought in the next growing season.
Selecting lawn fertilizer is a topic best saved for another column. If you have questions or would like a suggested turf fertilizing schedule, give my office a call at (217) 877-6042. A good rule of thumb in selecting lawn fertilizers is to choose ones with 30 to 50% insoluble (slow or time release) nitrogen. This will help promote slow, even growth rather than a big burst of quick growth.