Q: How much compost should I spread on my lawn in the fall?
—Sue Fusconi, Stonington, Conn.
A: Roger Cook replies: Compost is a great way to nourish roots and make a lawn stronger and greener. If you just spread compost on the surface, then 1/2 inch is about all you can add at one time without harming the grass. But you'll get much better results if you aerate the lawn first and get the compost down where it will do the most good.
The best way to do this is with a core aerator, which peppers the lawn with 2- to 3-inch-deep holes so air and nutrients can reach the roots. You can rent one and do the work yourself or turn it over to a lawn pro. After aerating, spread 1/2 to 1 inch of compost over the lawn and work it in with a plastic leaf rake. While you're at it, this would be a good time to add your usual fall fertilizer. Finally, give the lawn a good watering to work the compost down into the holes.
By the way, fall is about the best time to do this work. Aerating any earlier in the year encourages weeds to get a start.