Best Time to Sow Grass Seed

August 13, 2015 – Kenosha News

LawnQuestion: I live in Somers village, Kenosha. I plan to convert some of my existing flower beds back to lawn. I would like to ask your advice on the best time to sow lawn seed in the fall and the latest time I can sow? As I prepare the soil, I’m wondering whether your office provides any sort of soil analysis, so that I can amend the soil if necessary. H.B.

Answer: The best time to sow grass seed is August 15 to September 15.  You can plant later in September but you take the chance of new grass being damaged by cold. Kentucky bluegrass requires six weeks to germinate, and new grass plants should be tall enough to be mowed a time or two before winter.

My office does not perform soil analysis but I recommend a soil test by the University of Wisconsin Soils Lab to determine what, if any, amendments are needed before seeding. UW Soils Lab information and testing instructions are online at <a href=””></A>. Send the soil sample in a new zip-top plastic bag. An “official” soil test bag is not necessary. Indicate the test is for a new lawn. The fee for a basic lawn and garden soil test, which includes analysis and recommendations, is $15. If you need help interpreting the results, contact us. Mail your sample directly to the UW Soils lab in Marshfield, Wisconsin. You will receive your test results and recommendations via email or mail in approximately two weeks. If you prefer, soil test kits with instructions and a bag may be picked up at the Kenosha County UW-Extension office in the Kenosha County Center (19600 75th Street, corner Hwy 50 and Hwy 45, Bristol), by calling the garden helpline at (262) 857-1942, or by emailing <a href=””></A>.

While you are waiting for the soil test results, remove the existing plants, kill perennial weeds like quackgrass or dandelions and choose the best grass variety for your needs.

Prepare the soil using the soil test results. Plant a blend of Kentucky bluegrass cultivars for sunny lawns or fine fescues for shady lawns. Keep the ground moist until the seed germinates and the grass grows three inches tall.

For more information on lawn care, consult UW-Extension bulletin A3434 Lawn Establishment and Renovation at These publications can be opened and printed from your home computer for no charge by clicking on “view pdf.”


Barb Larson is horticulture educator for Kenosha County University of Wisconsin Extension. Gardening questions can be emailed to or call Master Gardener Volunteers at 262-857-1942.