If you reseed every three to four years you re-establish the lawn before it begins to thin out. This ensures the lawn stays thick and dense, which prevents weeds from invading. If you have pets or areas that receive a lot of foot traffic, you may have to reseed more often to prevent bare patches.

Can you overseed an existing lawn?

Overseeding can help you get back to the thick, lush, green lawn you've always wanted. By spreading grass seed over your existing lawn, you can thicken up the thin areas, and your lawn will start to look terrific again. (This is different from reseeding, which is when you start over and plant a completely new lawn.)

Do I need to overseed every year?

You should plan to overseed at least every 3 to 4 years, but, if you aerate and overseed every year, you'll see real nice results -- a lush, green lawn that fends off weeds, insects and diseases.