Experts across the country--from those at the University of Idaho Extension to those at the University of Illinois Extension--will all tell you the same thing. September is the time for planting a new lawn.
Why September is prime-time for seeding grass
The biggest reason September is a great time to plant grass seed is temperature. In September, soil temperatures drop into the ideal zone for germinating cool-season lawn seeds. But that's not all. Planting a new lawn in September, as opposed to October or November, gives the grass plenty of time to put down strong roots and really establish itself before winter weather hits. Another major factor is weeds. While spring has similar temperatures and offers a good long growing season before cold weather, in spring your new lawn has tons of competition from weed seeds. In fall, that's not the case. So not only can your lawn thrive in the cool soil and put down strong roots in the months before winter, your new grass is much likelier to be weed-free when you plant in the fall.
Tips for a successful September lawn installation
Planting in September isn't enough to guarantee new-lawn success. Preparing your soil, keeping the new grass moist, and applying a starter lawn fertilizer are all critical to growing a healthy new lawn. For more details, check out our full guide to planting grass seed.
