Editor’s note: I’m not the sort of person who feels guilty about very much. But one thing I do feel guilty about is that my kitchen scraps at home go into the garbage, and hence into a landfill. Not good. I plan to change that when, in the near future, I move from being a renter to home owner. To get me (and maybe you) up to speed on composting, I asked Paul Schmitt, our composting guru in Palo Alto, to do a guest post explaining how he makes compost. Paul not only composts his own kitchen odds and ends, but also everything from our Monday night dinners where he is a prep cook, and sometimes a musician. In his other life, Paul is a professional gardener who has a degree in mechanical engineering from the University of Michigan. Here, in words and photos, Paul shares his composting wisdom:
Composting can be done anywhere, anytime. It’s happening in the wild everywhere, always. Of course, you won’t want to do this when it’s unpleasant to work outside, but the compost will still work. Composting slows down in the winter and speeds up in the summer. It is common for people in snowy locales to build compost piles in the fall, when the trees contribute their leaves, and leave the pile alone until spring, when the air and soil are warm enough to work. In moderate and hot climates, you can build a compost pile any day of the year.
•1 compost bin with lid—minimum 3 feet tall and 3 feet square, a little bigger is better for the compost, but get one that will fit your yard.
•1 part kitchen scraps—this can be any food scraps from your kitchen (peels, shells, leftovers), except meat and dairy
•1 part green garden scraps—any leaves, greens, or weeds from your yard.
Don’t add any weeds with seeds, or runners if you don’t want them coming back, especially bermuda grass, crab grass, ivy, mint, or anything that is taking over your yard already; also avoid adding thorns from roses, bougainvillea, etc.
• 1 part brown garden scraps—dead leaves, straw, any dead dried plants, even shredded newspaper
• Water—a couple gallons to moisten the pile at the start
Should I Keep the Lid On or Off?
Keep the lid on most of the time. When it’s raining, a little rain helps keep the pile moist. Too much rain will slow the composting process down. It’s easiest just to keep the lid on. If the pile stinks for some reason, turning it and leaving the lid off for a few days will help eliminate the odor. In a very dry climate, the lid helps conserve moisture in the pile.
Where Should I Put My Compost Bin?
Place your compost bin in a level place in your yard away from any household entrance. Since you are going to be adding your kitchen scraps, make sure it is a convenient place for you, as close to the kitchen as possible. It’s helpful if the hose can reach the pile. In dry climates, like the arid West, put your compost pile in the shade or part shade, otherwise it’ll dry out too fast and work more slowly. You’ll also want extra space around your bin, for turning and working around it.
How Do I Take Care of It?
Start off your compost pile with a bunch of dry stuff, like several handfuls of straw and dry leaves. Then add any kitchen scraps you have on hand, and any trimmings, lawn clippings or weeds from your garden. Top off the kitchen scraps with more leaves, straw, or weeds. As you build your pile, make sure to keep the ratio approximately 1 part “green matter”—food and plant debris such as grass clippings (the nitrogen)—to 1 part “brown matter”—dry leaves and woody plants (the carbon). Every week, water your pile for a minute. If it’s really dry, water more. If it is moist already, don’t water. The goal is to keep the whole pile as moist as a wrung-out sponge. The outside of the pile will always be a little dry, so use your pitchfork to check the inside and see if it is moist enough. Every two weeks turn your pile with a pitchfork. The goal is to turn the pile inside out, flip the top to the bottom, and mix the whole pile up while you’re doing so. While turning it, you’ll start to see who’s moved in, such as worms, sow bugs, soldier fly larvae, or other organisms doing their composting work. If you notice it’s really dry, add water as you’re turning it. If it’s too wet or stinky or full of fruit flies, add more dry stuff (leaves, straw, shredded newspaper) to each layer as you turn.
When Is It Ready?
After a few weeks your pile is going to be a lot smaller than when you built it—that’s good! It means the organisms are eating it up and turning it into finished compost. You’ll have finished compost when the following happens:
• The pile is smaller than when it started
• You can’t recognize much of what you put in
• It has no smell or smells like fresh earth
• It looks darker, close to black (the color of humus)
• It is not hot anymore
Once your pile is finished composting, remove anything that you don’t want in your garden, like a piece of wood that didn’t decompose yet, or a corn cob that still looks like a corn cob—put those things in your next compost pile. Take the finished compost and use it as a soil amendment in your garden.
Compost can be used the following ways:
• Dug into the soil and mixed with a fork as a soil amendment
• Applied on top of the soil as a side dressing for plants (like mulch)
• Used in potting soil mixes for potted plants and houseplants
• Poured as a liquid fertilizer when mixed with lots of water