What Is the Best Time for Lawn Aeration and Overseeding?

When the first colonists arrived in America, the landscape consisted of prairie grasses and other unfamiliar species of grass. Not only did the lack of green lawns make the colonists homesick, they learned that the native grasses were not suitable for feeding livestock. So, they imported grass seeds from Europe. Those grasses adapted and thrived. Now, it’s up to you to help their descendants survive. You know that aerating and overseeding your lawn will help, but you don’t know when the best time for lawn aeration and overseeding is.

Let’s find out together.

What Are Aeration and Overseeding?

Aeration and overseeding are two separate processes. When you aerate, you remove small cores (about one to two inches deep) from your lawn. The cores are left on the top of your lawn to break down, feeding the soil below.

Overseeding is the process of putting down new grass seed. That can be where the grass is thin or where there is no grass. You can also overseed new grass seed on your existing lawn to help grow a thicker lawn.

Why should I aerate and overseed my lawn?

Many lawn care professionals say that aerating your lawn is an important part of maintaining a healthy lawn. Over time, your lawn may become compacted. It means that that the soil underneath your lawn is packed down. That can starve the roots of nutrients. When you aerate your lawn, not only do you help loosen the soil, you create holes in the soil. They help water and air reach the roots, which can improve your lawn’s health.

Unlike aerating, overseeding does not necessarily do anything to improve the health of your lawn. Generally, when you overseed, you are doing it for looks. However, overseeding your lawn can help defend against weeds. Overseeding your existing lawn can help it grow into a thick lawn. Thicker lawns tend to be more weed-resistant.

Should I aerate and overseed at the same time?

You don’t have to do the two together. However, when you aerate the lawn, you are exposing the soil. That creates more opportunity for the grass seed to germinate as it comes into direct contact with the soil, instead of laying on top of the grass.

What is the best time for lawn aeration and overseeding?

The best time for lawn aeration and overseeding depends on several factors. You want to aerate and overseed when the grass is in a high growth period. Different types of grass have different high growth periods. The climate you live in determines what type of grass you likely have and that influences when the high growth period occurs.

What Kinds of Grasses Are There?

There are two types of grasses used in North American lawns. They are cool type grasses and warm type grasses. Each of these grasses has evolved and adapted to thrive in specific climate conditions.

Cool type grasses

Cool type grasses, like Kentucky Bluegrass and Perennial Ryegrass, have adapted to a climate that experiences year-round temperature changes. They have learned how to survive frigid winters and hot summers. However, cool type grasses grow best when the temperatures are between 60 and 75 degrees Fahrenheit. That means that spring and fall tend to be the peak growing season for these grasses.

Warm type grasses

Warm type grasses are originally from tropical areas. Common types of these grasses include Bahiagrass and Bermudagrass. These types of grasses grow best in tropical climates and have their peak growing season when temperatures are between 75 and 90 degrees Fahrenheit. That means that even in warmer climates, peak growth is during the summer months.

Which Grass Do I Have?

There’s no way to know exactly what species of grass is in your lawn (unless you’ve planted it yourself). However, there are general guidelines for the best time for lawn aeration and overseeding by probable grass type, climate, and time of year.

In the north or northeast

If you live in the north or northeast, you probably have a cool type grass. The best time for lawn aeration and overseeding is in the late summer to early fall. Not only will your grass be at peak growth, but this also gives the seeds a chance to take root before the first frost.

In the south

You probably have a warm season grass. The best time for lawn aeration and overseeding is during the late spring to early summer, just as temperatures are heating up. It is the best time for the seeds to take root and grow.

In the midwest

Midwestern lawns tend to have cool season grass. Just like in the north and northeast, the best time for lawn aeration and overseeding is late summer and early fall.

In the west

It depends which part of the west you’re in. If you’re in the northwest, you probably have cool grasses. But, if you’re in the southwest, you probably have warm grasses. Either way, the best time for lawn aeration and overseeding is about six weeks before winter.

Going Green

It doesn’t matter if you spend your weekends maintaining that picture perfect lawn, or you farm the job out to professionals. Knowing the best time for lawn aeration and overseeding will go a long way toward helping you improve the health of your lawn and extend its life.

And, while you may not be using the grass for raising cattle, a healthy lawn is one you can enjoy for a long time.