If your lawn is hard, almost painful to walk on, you might need to aerate. If you lawn is coated with weeds, especially plantain and crabgrass, you probably need to aerate. If you try to drive a shovel in the ground and all you come up with is a thimble full of hard-pan clay, you definitely need to aerate. And do it now if you want to take a major step toward having a better lawn next season. ...