Composting wood chips: Should the pile be covered with a tarp?

October 25, 2020 8:42 AM

I have a pile of fresh arborist wood chips (1.5 cubic yards) that I want to compost. I plan to layer the chips with green materials. Should I cover the pile with a tarp to prevent rain and snow from leaching out the nutrients? I am concerned because I live in an area that gets a substantial amount of rain in the fall and spring and at least several feet of snow in the winter. I would remove the tarp occasionally to spray the pile with water to keep it moist. Would a tarp encourage the growth of mildew?
posted by kirsti to Home & Garden (4 answers total)

Compost does not need to be covered, and covering can cause problems. I would not cover it.
posted by SaltySalticid at 8:52 AM on October 25, 2020 [4 favorites]

I would leave your pile uncovered. The nutrients will move down if anything. A tarp wouldn't prevent leaching, but I don't think leaching is really much of a concern. The center of your pile will be where things will remain active in winter temperatures. It needs lots of moisture in order to break down the material you've put in, and the occasional spraying isn't going to keep it moist enough. Lots of rain and snow is actually your friend in the composting process. Not much is really going to be happening in the cold tempatures anyway (depending on the size of the pile of course).
posted by WalkerWestridge at 8:52 AM on October 25, 2020 [1 favorite]

As wood decomposes, it takes up nitrogen, so leaching would not worry me. I have lots of trees and the roots find the compost and love it, making it harder to dig out and use, so I put something at the bottom, lately a piece of vinyl flooring that I had. To speed it up,you can add urine, seems weird but works, add nutrients. I have a hands off approach to composing, don't think covered or not will matter much. I cover my wood pile, loosely, no mildew, rot is greatly reduced, so maybe uncovered, as you want rot.
posted by theora55 at 9:08 AM on October 25, 2020

A loose covering of semi-permeable barrier like cardboard may be an intermediate option. It will retain some moisture while also breaking down and, even when intact, will allow gas/vapor transfer.
posted by late afternoon dreaming hotel at 8:42 AM on October 26, 2020