When to Plant Grass Seed in Illinois for a Lush Lawn?

Written by

William Golder


Dorian Goodwin

when to plant grass seed in illinois

Illinois has a favorable climate for establishing turfgrass. But on the whole, it’s still necessary to know when to plant grass seed in Illinois so that your seeds can spread roots and grow without incurring damage from adverse weather.

In short, the ideal planting season in the state is around August 1 to mid-September in the fall and within March to mid-April in the spring. Though spring seeding up to the middle of June is possible, it’s better to plant earlier to avoid the harsh summer heat.

Best Time to Plant Grass Seed in Illinois

1. Plant in the fall from August to September


Fall is the best time to plant grass because the soil during this season is warmer than early spring, which allows seeds to establish roots quicker. Another plus is that weeds are not actively growing during autumn, so your lawn has less competition for nutrients.

With that said, below is the time for fall grass planting you can take note of. I recommend deducting 45 days from the first frost date to determine the latest seeding schedule.

For example, those in Chicago, IL will probably experience their first frost on November 1, making September 17 the final grass sowing time.

Here are the gardening dates for different parts of Illinois.

  • In southern Illinois – August 30 to September 15
  • In central Illinois – August 15 to September 15
  • In northern Illinois – August 1 to September 15

2. Plant in the spring in March and April


March and April are the best months to start or overseed lawn in the spring in Illinois. However, there are some caveats to keep in mind with this recommendation:

  1. To begin with, April is when weeds begin growing, so if you apply a herbicide to kill them before putting grass down, you’ll have to delay seeding by 30 days for the weed killer to lose efficacy.
  2. As a result, planting turfgrass would be impossible before May if the herbicide application is in April.
  3. What’s more, there will be less time for the grass seedlings to establish roots before summer comes, and you’ll need to irrigate the soil more frequently to protect the plants against high temperatures.
  4. So, if you want to sow grass on time, skip the herbicide.

In any case, the general rule for growing grass in spring northern Illinois and other regions of the state is after the final frost.

If you start your lawn too close to the summer, consider opting for warm-season grass instead of cool-season varieties. But note that warm-season turf will be harder to find in IL and will only remain green from June to August.

As for how late to plant seeds in the spring, no later than the middle of June is the general guideline.

Tips for Successful Grass Seeding in Illinois


  • Eliminate all weeds by digging, tilling, or herbicide application. Follow the herbicide’s instructions if using one, or dig around the weeds with a shovel down to a depth of four inches, then grab the center roots and pull the weeds out to discard them.
  • You should also incorporate compost or manure into the ground to boost its organic content. A soil test to determine missing nutrients will come in handy, but if you don’t have one, a balanced 10-10-10 or 12-12-12 fertilizer may be used.
  • Last but not least, remove all rocks and debris before planting grass. Follow the seeding recommendation of your variety to ensure a thick lawn.

Fine fescue often requires 5 pounds of seeds per 1,000 square feet, for example, while Kentucky bluegrass will spread well with 1 to 5 pounds of grass per 1,000 square feet, depending on the seed blend.

  • After sowing, rake the soil to press the seeds down before watering them. Irrigate with one to 1.5 inches of moisture per week and cover the ground with straw mulch to prevent drought.



What is the best time to lay sod in Illinois?

The time for laying sod is the same as the schedule for planting seeds: lay sod in the fall if possible, or choose spring if you missed the fall growing season.

Keep in mind that there are 2 types of grass seeds: cool-season and warm-season. In Illinois, property owners typically have the cool varieties, making fall the optimal time for sod installation.

What is a good grass seed for overseeding?

Most popular types of grass in Illinois are cool-season ones, owing to the state’s colder climate of hardiness zone 5 to 7. Some grasses suitable for overseeding here are perennial ryegrass, fescue, and Kentucky bluegrass.


We hope this article answered all your questions concerning when to plant grass seed in Illinois. Whether you’re primping your lawn in spring or fall, remember to look up the frost dates where you live and plan accordingly.

Your seeds won’t grow well if you subject them to extreme heat, either, so be mindful of the temperature, which should be 60 to 75 degrees Fahrenheit for germination.

Other locations you can refer to know the best time to plant grass seed:

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