Fall Composting

Now that your summer vegetable garden has fed you, it’s time to return the favor.

Feed your soil with rich homemade compost, and you’ll replenish the nutrients that your rapidly growing crops gobbled up. Many vegetables, including corn, broccoli and asparagus, are heavy feeders, extracting copious amounts of nutrients in short order.

That’s why old-time gardeners rotate crops and let fields lie fallow.

But by returning decomposed organic matter to your plot, you’ll bring the soil back to balance. You’ll also attract beneficial microorganisms and improve fertility, texture and drainage.

The Basics

All living matter decomposes eventually—whether it’s withered remains of vegetable plants, miscellaneous trimmings from the garden or scraps from your table. The resulting light, crumbly material teems with beneficial microbes that are just waiting to go to work in your soil.

You can kick-start the process by setting up a compost system.

It’s simple—especially if you focus on two key ingredients: carbon and nitrogen.

One of the handiest sources of carbon is wafting to the ground right now, as our deciduous trees are conveniently shedding their autumn leaves. Those desiccated bits are, at least figuratively speaking, autumn gold for a compost pile.

Additional sources of carbon include such brown or dried material as twigs, straw and sawdust. Or, if you’re feeling ambitious, you can “grow” carbon by sowing corn, wheat, millet, amaranth or oats. Harvest the plants, then shred the leaves and stalks for compost.

The other key component, nitrogen, comes from green material. That includes lawn clippings and fresh yard trimmings. Vegetable scraps are green, too, while stale bread and leftover pasta are brown.

Setting Up Your Bin

A compost pile should measure at least 3 feet tall, 3 feet wide and 3 feet deep. Rather than piling materials on open ground, corral them in a store-bought bin or build your own, with four 4- by 4-inch redwood posts; slats or chicken wire; and a tarp. By reining in the contents, you’ll hasten decomposition, keep out rodents and prevent pets from nosing around.

For quickest results, chip, chop, hack or cut the materials into pieces about an inch in size. The more surface area you expose, the more rapidly the pieces will decompose. Then fill the entire bin at once. A good starter mix is three parts carbon to two parts nitrogen. Layer the carbon and nitrogen as you go, moistening each layer until it’s the consistency of a wrung-out sponge.

The pile should begin to heat up within a few days, which indicates that those beneficial microbes have sprung into action. If your pile does not heat up, add green material, seaweed or blood meal. If your pile appears slimy and reeks of ammonia, blend in more carbon.

Once you feel the heat, keep those microbes churning by turning the pile every few days and watering it once a week. As the components break down, they will turn brown. Sniff a handful. When the mix smells fresh and earthy and crumbles through your fingers, it’s done. Sift out any lumps and use them to start your next batch.

A Few Tips

Here’s a trick for thick autumn leaves: We have a mature sycamore tree that blankets the yard with fuzzy leaves. We rake a layer onto the lawn, then mow. The mower chips the leaves while it cuts the grass, creating a perfect mix of carbon and nitrogen. If our bins are full, we spread the mix, a couple of inches thick, in any raised vegetable beds slated to rest until spring. We water the beds occasionally, and rough them up with a steel rake if the leaves mat or get slick.

You can also run leaves through a chipper or dry them in shallow temporary piles. When the leaves become brittle, bag them up and stomp on them. Then pour the bits into your pile.

The shriveled remains of summer vegetable plants are a good source of carbon as well. Chop dried corn stalks, zucchini vines and the like. But don’t compost tainted tomato leaves or anything else that might transmit disease. Also avoid meat, bones, dairy products and animal or human waste. Home compost piles rarely achieve high enough temperatures to kill pathogens.

As for green material: If you don’t have a lawn or fresh trimmings, look to your neighbors. But make sure their clippings are fresh and have not been sprayed with herbicide. Avoid Bermuda grass, which can contaminate your compost—and yard—with pernicious seeds.

For that matter, don’t throw any weeds bearing seed heads in your compost. Again, your pile is unlikely to attain high enough temperatures to sterilize the seeds. And after all, your goal is return good things to the earth.