The Best Time to Seed Grass in Cold Climates

Target Dates

• Regardless of cool-season grass type or location in the northern U.S., the best time to sow grass seed is from mid-August to mid-September. This time frame takes advantage of the warm soil and gradually cooling temperatures of fall to quickly and most thoroughly establish new grass before winter. Soils become cooler and stay moister in the fall, and few weed seeds germinate at this time, potentially disrupting the grass seed germination and infesting the new lawn.

Overseeding Insight

• If you miss the window for sowing grass seed in late summer, do not sow seed between mid-September and the first fall frost in your area. Any small, tender, newly germinating seedlings that experience the first frost may not be strong or mature enough to survive, so waiting until after frosts occur is best to broadcast seed over the soil. The option to sow grass seed before the snow flies in late fall -- letting it sit dormant on the soil over winter and then germinate early in spring once conditions are favorable -- is possible in the northern U.S. Two drawbacks exist, however: Birds may eat the seeds on the ground, and any rains or snow melt may wash the seeds from the soil leading up to spring.

Spring Sowing

• Northern gardeners may choose to successfully sow grass seed in many seasons that are cool and supply damp soils. Cool-season grass seed may also be sown in early spring, in March or very early April. If the weather is unusually cool and moist, seeding as late as May 1 may be possible. More maintenance and monitoring is involved with spring lawn grass sowing, since weed seeds also germinate more readily, and irrigation is needed to offset the intensifying sun rays and warming spring temperatures leading into summer.

Soil Preparation

• Independent of the time of year you choose to sow grass seed, proper preparation of the planting site is required. The best time to sow grass seed is after a well-prepared soil bed is made. Rake the planting area, breaking up soil particles and removing rocks and debris. Grade the area smooth, eliminating any depressions or gullies that would cause excessive water runoff and erosion. Also remove all weeds from the planting area before you scatter grass seed. Treating tough, perennial weeds with herbicide a couple weeks before sowing may be necessary to ensure the planting area is as clean as possible.