By George Weigel/The Patriot-News
Q: In Thursday's paper, one of the ways you mentioned about helping a lawn was to put a quarter-inch layer of compost on the lawn. Well, I have a ruler that measures a quarter-inch, but where do I get the compost and how do I spread it a quarter-inch layer thin on my lawn? It sounds like a good idea. Would a quarter-inch layer of topsoil do the same?
A: This is called "top-dressing," and the idea is that it's a way to gradually add organic matter and build up the lawn soil without digging everything up and starting over. A big problem so many people have with their lawns - especially in developments that were heavily graded - is that the underlying "soil" is terrible. It's more like a thin layer of shale or clay on top of subsoil.
The trick with top-dressing is adding only enough new organic matter that it aids the soil without smothering the existing grass. A quarter-inch layer is enough that the grass crowns can slightly elongate to adapt to the slightly higher soil surface. It's also important to use something that's light-weight and high in organics, such as compost, peat moss or a blend that's akin to what you'd grow potted flowers in. If you'd dump an inch or two of ordinary, heavy garden soil on top of the lawn, you'll kill the grass.
I make my own compost and sift some of it at season's end for use on the lawn. I do a section of the lawn each fall. You can also buy bulk compost or light-weight soil blends, typically from the same vendors that sell bulk mulch. I've also used bales of sphagnum peat moss. I break up the chunks in a wheel barrow before applying it.
Two ways to put down your top-dressing. In small areas, just scatter it with your hands. In bigger areas, dump little piles and rake out to about a quarter-inch thickness. Fall is an ideal time to do this. You can even core-aerate and overseed first, then top-dress in the end to give a light covering and nutrient boost to the new seed. It's a bit of work, but I think top-dressing is one of the best things you can do in any lawn-care program.