If your lawn is healthy we usually recommend just power raking in spring and aerating in fall. If you’ve had problems with dandelions, or the grass is coming in a bit yellow, or if your lawn suffered under a baking heat wave last year, aerating in the spring might be valuable for you. We have many customers who prefer to do both aerating and power raking in spring so that the lawn comes in strong and green a bit faster, and we’ve seen that it does tend to work. For most lawns though, aerating in spring is overkill.