The Best Time to Plant Grass Seed in Illinois

lawn in front of a house in illinois

With the exception of Zoysiagrass, most grasses in Illinois are cool-season grasses, so the best time to plant grass seed in Illinois is during late summer and early fall, from August through September.

Timing is everything! The Land of Lincoln is cloudy all year round, with wet, humid summers and freezing winters with lots of snow and wind. The success of your new grass seedlings will depend on what time of year you choose to plant.

When to plant grass seed in Illinois

Illinois Plant Hardiness Map

According to the USDA Plant Hardiness Zone Map, Illinois is in zones 5, 6, and 7, which are zones where cool-season grasses thrive. That means that the ideal time to plant the best grass seed in Illinois is late summer to early fall so the young grass has two or three months to establish before the weather becomes too cold. 

Fall planting also gives cool-season grass the full spring season to establish before the hot summer months.

Your location in the Prairie State will affect the exact window of time you have to start planting your grass seed.

  • Northern Illinois: Early August to early September
  • Central Illinois: Mid-August to Mid-September
  • Southern Illinois: September

If you are unable to seed your lawn during these months, then April is the second best time to start since it is right before the heat of summer and after the spring frosts.

When to plant cool-season grasses in Illinois

growth of cool season grass
Infographic by Juan Rodriguez

Here are the best cool-season grasses for your Illinois lawn and the best times to plant them:

Kentucky bluegrass

closeup of kentucky grass in a lawn

Like any cool-season grass, Kentucky bluegrass (KBG) should be seeded in the fall, specifically in September.

KBG is a favorite grass among northern homeowners thanks to its resilience in harsh winters and ability to heal from damage. However, it’s a high-maintenance grass type that prefers full sun and isn’t very tolerant of shade. KBG is often mixed with perennial ryegrass to get the best of both worlds since KBG is more drought-, disease-, and wear-tolerant but has a slower germination period.

Grass Seed Options:
Jonathan Green (11970) Blue Panther Kentucky Bluegrass Grass Seed (3 lbs.)
SeedRanch Midnight Kentucky Bluegrass Seed (5 lbs.)

Fine fescue

fine fescue grass
Aaron Patton | Purdue’s Turfgrass Science Program

The best time to seed fine fescues is in the early fall, though late fall is fine for dormant seeding in some areas. Illinois is not a high-elevation state, so fine fescues can also be planted as soon as late summer.

Fine fescues are actually a group of grasses instead of a single grass. The species that grow best in Illinois are:

  • Chewings fescue
  • Hard fescue
  • Creeping red fescue

Fine fescues are shade-tolerant, low maintenance, and drought-resistant. However, they are not very tolerant of foot traffic or heat. They also tend to be vulnerable to thatch and some of the most common fine fescue diseases.

Grass Seed Options:
Outsidepride Legacy Fine Fescue Grass Seed (5 lbs.)
Eretz Creeping Red Fine Fescue Seed (choose your size)
Outsidepride Creeping Red Fine Fescue Grass Seed (25 lbs.)

Perennial ryegrass

pyrennial ryegrass in a lawn
Aaron Patton | Purdue’s Turfgrass Science Program

Perennial ryegrass’s peak growing season is during late summer (August) to early fall (September)

Perennial ryegrass (or PRG for short) is a bunch-type cool-season grass commonly mixed with KBG or fine fescue. It is well-known for its striping ability and high tolerance to foot traffic. However, it has a low tolerance to shade and drought, a high potential for disease, and a poor ability to recover from damage. 

On the plus side, it’s not prone to thatch and has a fast germination time, so overseeding will easily fix any damage your perennial ryegrass takes. 

Grass Seed Options:
Outsidepride Perennial Ryegrass Seed (5 lbs.)
Eretz ProTurf Perennial Ryegrass Fine Lawn Seed (choose your size)

Tall fescue

hand touching tall fescue grass
Aaron Patton | Purdue’s Turfgrass Science Program

As a cool-season grass, tall fescue does best if established in the fall so it has plenty of time to establish deep roots before summer. 

A coarse, bunch-type cool-season grass, tall fescue thrives in fertile soil with good drainage, though it can tolerate a wide variety of different soil types. Tall fescue has a moderate tolerance for drought, shade, cold, and foot traffic, as well as a low potential for lawn diseases. 

However, like PRG, it struggles to recuperate from damage and will need to be reseeded to repair any patchy, damaged areas.

Grass Seed Options:
Triple-Play Tall Fescue Grass Seed Blend (5000 sq ft)
Eretz Kentucky 31 K31 Tall Fescue Grass Seed (choose your size)
Pennington The Rebels Tall Fescue Grass Seed Mix (7 lb.)

When to plant warm-season grasses in Illinois

growth of warm season grass
Infographic by Juan Rodriguez

Though most grass types in Illinois are cool season, there is one warm-season grass that thrives in the Land of Lincoln. Warm-season grasses are able to successfully reap the benefits of the warm weather while having plenty of time to establish before the fall.

Here is the best warm-season grass for your southern Illinois lawn:


closeup of zoysiagrass in a lawn
Forest & Kim Starr | Wikimedia Commons | CC BY 3.0

For the best results, Zoysiagrass should be seeded during mid to late spring or during early summer. However, keep in mind that Zoysiagrass is more difficult to establish with seed, and most experts recommend laying down sod.

Zoysiagrass is a warm-season grass with a blade texture that ranges from fine to coarse. This grass type is slow to grow and slow to recover from damage, but it has plenty of pros. For instance, it is salt tolerant, drought resistant, and has a high tolerance for foot traffic. 

Zoysiagrass is soft to walk on, crowds out weeds, and works in a variety of soil types. Zoysia’s pros outweigh the cons, so Zoysiagrass may be just what you need if you live in southern Illinois.

Grass Plug and Seed Options:
Zoysia Plugs (50 Large Grass Plugs)
Zoysia Plugs (50 Full & Lush Grass Plugs)
Zoysia Plugs (100 Plugs)
Zenith Zenith Grass Seeds (1/8 lb. of seeds)

How to plant grass seed in Illinois

Knowing how to plant grass seed in your lawn is simple and can be done in a few easy steps:

  • Choose the best grass seed for your lawn and location.
  • Clear your lawn of dead leaves, twigs, branches, and other debris; then use either an herbicide or a sod cutter to remove the existing turf.
  • Prepare your soil by aerating and applying fertilizer, compost, or topsoil as needed. You can determine what your soil needs by taking a soil test. (Read How to Soil Test Your Lawn for more information.)
  • Start planting your grass seed. If you have a small lawn, you can sow the seed by hand, but you should use a broadcast spreader for larger areas. Fill half the spreader with seed and walk back and forth from north to south until you’re finished. Then fill the other half and cover from east to west.
  • Lightly rake over the seeded surface with the back of a rake for better seed-to-soil contact.
  • Cover the area with straw mulch to protect it from the heat and birds.
  • Lightly water the lawn two to three times a day until the seedlings are an inch tall.
  • Gradually reduce watering until you get to the recommended watering schedule for your chosen grass.


When is the best time to overseed your Illinois lawn?

The best time to overseed your lawn in Illinois is mid-August to mid-September. The truth is, there isn’t any difference in the best time for overseeding or seeding a new lawn since it all boils down to your grass’s peak growing season.

When is the best time to lay sod in Illinois?

As long as the ground isn’t frozen and there’s plenty of water, the best time to place new sod is anytime during April or September. Cool temperatures combined with occasional rain help sod establish quickly.

What is the best grass type for Illinois?

The best grass type for your Illinois lawn will depend on where you are in the state. For example:

  • Northern Illinois: Kentucky bluegrass and fine fescue
  • Central Illinois: Kentucky bluegrass, fine fescue, tall fescue, and perennial ryegrass
  • Southern Illinois: Tall fescue and Zoysiagrass

This doesn’t imply that you can’t plant any other types of grasses if you live in these areas of Illinois. All the grasses mentioned in this article are inside Illinois hardiness zones. It just means that these particular ones will thrive the best.

Hire a pro

No matter your grass type, overseeding, mowing, irrigating, and maintaining your lawn are all important for its health and curb appeal. Let Lawn Love connect you with lawn care professionals in your area for all of your lawn care needs.

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Main Image Credit: Bilyan Belchev | Wikimedia Commons | CC BY-SA 4.0

Lydian Pine

Lydian Pine is a creative writer and studio artist whose work first debuted in a short story anthology. She graduated from the University of North Texas in 2020 and enjoys video games, theatre, and swimming. Lately, she has started to study entomology as a hobby.