Whether you're repairing bare spots, overseeding an existing lawn or starting from scratch, you can generally expect grass seedlings to emerge within seven to 21 days when grown under proper conditions. It may take another three to four weeks of growth before grass is long enough to mow.

Is it OK to let grass go to seed?

When you let your grass go to seed, you're actually letting weeds grow, eliminating any control you had over them. ... It actually helps your grass stay strong. When you forego mowing, and your grass grows to excessively high levels and goes to seed, you're doing more harm than good.

What time of year does grass produce seeds?

Plant cool-season grass seed in late summer or early fall (when daytime temperatures lower to about 60 to 75 degrees) for best success. September is typically the best month, although you might be able to get away with seeding as early as mid-August or as late as mid-October; it all depends on the forecast.