Most home gardeners will not be able to create true compost.

They don’t produce enough compostable material in the right proportions of carbon and nitrogen to promote the chemical reaction that decomposes organic material at high enough temperatures to kill weed seeds.

Despite that, they should compost their yard and kitchen waste, especially now that they are stuck home most of the time. Good enough is better than nothing at all.

For those with a fairly large property who want to try true composting, I’ll give you the rules as explained in University of Maine Cooperative Extension bulletins 1143 and 1159 and a MOFGA article written be now semi-retired crop specialist Eric Sideman.

All living material – the things you would toss into your compost bin – contain carbon and nitrogen. The ideal ratio of carbon to nitrogen in a compost bin is 30 parts carbon to one part nitrogen. Grass clippings have a ratio of 20 to 1, while the leaves you rake in the fall are 60 to 1. For table scraps – you shouldn’t compost meat and bones – the ratio is 15 to 1.

If you toss material in the proper proportions in a pile or bin that is at least 27 cubic feet (a cube that’s 3 feet on all sides) and less than 125 cubic feet (a cube that’s 5 feet on all sides), you can create true compost, although some mixing is usually required.

Here are the problems with that process. The grass clippings – and if people are shrinking the lawn like they should be, there won’t be many – come from May through September and the leaves, of which there are lots, in October. And with all the hunger in the world, people should feel guilty producing much food waste. Coffee grounds, tea bags and peelings from some vegetables should be it.

Anyway, toss all the stuff together, mix it occasionally, and you end up with compost you can use in your yard, with no weeds because of all the heat the composting creates.

That’s the way it should be done. What follows is what my wife, Nancy, and I do.

We have 10 of what I loosely call compost bins on our property, and only two of them come even close to producing true compost – and they don’t reach temperatures high enough to kill weed seeds.

Eight produce leaf mold, not compost, and they are located near the wooded part of our property.

Those eight are made with pallets that can be picked up for free at transfer stations and some commercial enterprises, tied together with pieces of rope. Each fall, when raking leaves, I dump the raked leaves into the bins. If I have time – and I didn’t at the end of last fall when snow was forecast – I chop them up. I now use a leaf shredder but used to use a lawn mower.

The following August, the volume of the leaves is about a third of what it was in the fall. As I start clearing out parts of the vegetable garden – where spring peas grew, for example – I spread the leaf mold there and let it decompose further before I turn it into the soil the following spring.

The only problem I have had with this method is that, especially this year because there were so many acorns last fall, I’ve been spending a lot of time pulling baby oak trees out of the vegetable garden.

In the vegetable garden, we have two bins that produce something closer to compost. One is similar to the leaf bins, made of four pallets. The other is a commercially made plastic composter called The Earth Machine, which the town of Cape Elizabeth sold a few years ago to coax residents into composting. The Earth Machine and similar systems are still available commercially.

The Earth Machine gets all of our kitchen scraps, including lobster shells, but not meat or animal bones. It also gets weeds and other plants that come from the vegetable garden. Because it is enclosed, I have to take off the top and add water occasionally. Every few months, I’ll pull open a small door at the bottom of the bin and pull out good compost. I moved the bin from its first location after about four years, and it is on its second location now.

We used to put that kitchen waste in the compost bin made of pallets, but crows and other living things would take a lot of the potential compost (they love lobster shells and coffee filters) out of the bin and scatter what they didn’t eat all over the yard. It was messy, so we bought The Earth Machine, which is much neater.

The pallet bin gets true garden waste: some weeds, some tree leaves but mostly garden refuse such as rhubarb leaves, pea vines, pea pods and the asparagus plants I cut down in the fall. The pallets in that bin last three to four years before they begin to rot themselves, and I find a new site in the garden.

The compost from both of them is rich in organic matter, even if some of the weed seeds are viable. I can pull those weeds at the same time I do the baby oak trees.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: [email protected]


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