Composting Kitchen Waste Can Be Tricky!
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Question of the Week © 2018 Mike McGrath
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Composting Kitchen Waste Can be Tricky
Q. I have filled three large black sealed composting bins with fruit and vegetable waste (pineapple skins, squash skins and seeds, mango & avocado skins and seeds, egg shells, coffee grounds, etc.) plus grass clippings and soil. But the material does not break down. I add water and chop up and stir the contents, but it still doesn't break down. I can only guess that we used too much fruit and veggie waste. We don't want to just put everything in the garbage. Your advice please, on how can we get this large amount of material to break down.
---Dan in North Augusta, South Carolina
A. This is the classic mistake of rookie composters. They read the list of things that can be put into their composters and right there it says: "kitchen waste and grass clippings"; so they fill their composters with kitchen waste and grass clippings, just like the list tells them to…
But we have yet to see a list that emphasizes the need for a majority of "dry, brown materials" like shredded fall leaves in the mix. "Green" materials like grass clippings and kitchen waste don't really even become a significant part of the finished compost; they just provide food for the organisms that turn the 'dry browns' into black gold.
Revealing this unfortunate fact is not a popular stance. My Ted Talk on composting is fast approaching a million views; and whenever I check in on it I'm always surprised by the number of comments from people who claim to have made compost out of nothing but big piles of kitchen waste. It just doesn't work that way! (BTW—if you want a more honest look at the comments, click on the little button that says 'most recent'; I suspect that the negative guy who's always on top might be voting for himself a couple hundred times a day….)
But many people come to composting just because they want to do the right thing with their kitchen waste; and so they pile it up. Luckily, Dan is using recycled black plastic composters with locking lids, so at least his vermin problems should be few. The only thing worse than trying to recycle kitchen waste alone in a composter is trying it in an open pile, where you wind up feeding rats, mice, raccoons and other mammalian enemies of mankind while not making good compost.
In the future, Dan needs to shred up lots of fall leaves and make those shredded leaves the bulk of his piles' ingredients. A ratio of four parts shredded leaves to one-part green waste is ideal. As soon as the leaves start falling, you should start shredding them up every day. Either bag the shredded leaves or pile them up in an open bin so you'll have a good amount to add to the mix every time you bring a load of garbage out to a sealed bin. A lot of shredded leaves and a little bit of garbage makes fine compost (especially if there's lot of coffee grounds in the kitchen waste).
(And yes, the leaves must be shredded. Whole leaves take forever to break down; and you can store at least ten times as many leaves in one bag if they're shredded first.)
Now: what should Dan do with his current crop of non-compost? It really would be a shame if he had to throw it all away.
He has a couple of options.
• Option One: If he has immediate access to dry brown materials—leftover fall leaves that didn't get raked, cornstalks, sunflower stalks, browned-out ornamental grasses—he can shred them up and make new, more proper piles where the garbage is a minor player. (But not shredded newspaper or junk mail for the 'dry browns' because these materials have no nutrition value. And not wood chips or sawdust, because they take too long to break down.)
• Option two: Turn those stinky bins into giant outdoor worm composters! In most climates, worm bins are indoors only, as the specialized redworms that do the work of turning kitchen waste into wonderful soil can't survive freezing temperatures. But several listeners in more temperate climes have written to say that they have used redworms in outdoor bins and it seems to work well.
Dan's South Carolina weather—especially from here on out (its March as we post this informative article)—should be perfect for keeping the worms alive and active. Just try and get things finished before the temps soar up into the 90s, as redworms can't take excessive heat either.
Big difference here from Option One: The brown material used as bedding in indoor worm bins is typically shredded newspaper as opposed to leaves. And that's still going to be the case outdoors. I've tried using more 'organic' bedding materials like shredded leaves in my indoor bins, but the redworms clearly do their best work with shredded black and white newsprint.
Now—how exactly should Dan transmogrify his garbage dumps into worm bins?
Get a supply of 'composting worms'—not earthworms. You can get these specialized redworms online or at hipper independent garden centers. Add some worms to each bin, cover them with, let's say, four or five inches of shredded newsprint and then add just enough water to keep the newspaper moist. The worms will do the rest; and after a few months, Dan should have some nice compost-like worm castings to use in his garden.
In the future, be sure to collect and shred enough dry brown material as it becomes available in the fall to make sure you'll have four parts of brown stuff on hand for every part of kitchen waste you want to recycle for the entire coming year.
Oh—and no more grass clippings in the compost! Period! Grass clippings just add more 'green' to piles that need 'brown'. And they're 10% nitrogen, which is the perfect lawn food, and should always be left on the lawn.
And if you're in a cooler climate, get a worm bin for your kitchen waste!