|Our new home has 3 garden plots totaling nearly 1000 sq. ft. The area is clay and quite damp. We are putting our grass clippings & dead leaves on top of the areas, hoping the mulch will decompose over winter. We presently have about 2 inches of grass clippings topped with about 4 of dead, unpacked leaves. Should this pile turn into compost by next spring or can we lay more dead leaves on still?
|Decomposition slows down dramatically in cold weather, so the leaves and grass clippings will probably not do much decomposing over the winter. The best method is to build a compost pile, alternating layers of carbon-rich material, like dried leaves and old grass clippings, with layers of nitrogen-rich material, like manure and fresh, green plant material.
Since smaller pieces of material compost faster than large pieces, if possible shred the leaves. You can either rent a chipper/shredder or simply run your lawn mower over the pile several times. You can then add these to the compost pile for faster decomposition.
I wouldn't spread any more leaves on your garden right now. I'm afraid you'll just end up with a thick mat of wet leaves next spring. Not that that would be bad for the soil, but it would make tilling more difficult. If possible, till the garden now, before winter sets in. Then you can pile a layer of leaves over the surface to help protect the soil from erosion and suppress weed growth. If you aren't going to till this fall, begin a big leaf pile for adding next spring. Pile the leaves, whole or shredded, and cover them with a tarp. Some decomposition will take place over the winter--the pile won't freeze as fast as the thin layer over the soil--and you can use the leaves next spring, either tilling them in or using them as mulch. By all means keep those leaves to use! As you probably know, adding lots of organic matter is the best way to lighten clay soils.
You might also want to have a soil test done. If it indicates an acid soil, you might want to apply some lime this fall and till it in with the leaves. That way it will have time to do its work over the winter.