Different styles of composting bins. (Adrian Higgins/The Washington Post)

There is every reason to expect this year’s fall leaf color to be a stunning show after a particularly verdant growing season. For gardeners, this is one rainbow with a real and tangible pot of gold at the end of it.

Autumn leaves are possibly the most valuable single ingredient in creating humus, the organic matter that brings soil to life and makes garden plants more healthy and vigorous. Either alone as rotted leafmold or as the matrix of the compost pile, the leaves of October and November are the lifeblood of next year’s organic garden. And yet residents will spend hours gathering this material to set out on the street to be taken away. Some of us actually pay others to do this for us.

In Fairfax County alone, crews last year collected 32,478 tons of leaves and other yard waste. Many jurisdictions turn fallen leaves into a leaf compost for use by residents the following year. This back-and-forth recycling is commendable, but surely a better course would be to keep the leaves — and other yard waste along with kitchen scraps — from leaving the home in the first place.

This leaf-raking season, consider establishing your own composting operation.

Yes, composting can go wrong — attracting rodents or simply smelling bad — but those liabilities are associated with a few missteps. With a little care and effort, compost piles are real assets, not just as a practical source of black gold but in instilling a sense of nurturing a greener world.

Compost is plant and other natural debris that has been converted into decayed matter by a whole web of organisms that range from sowbugs and earthworms to tiny arthropods to microbes.

Compost contains some nutrients, but it is not a fertilizer. Its value is in improving the structure of soil and its capacity to hold nutrients and moisture. Compost is also rich in beneficial fungi and bacteria that help plants to grow and stay healthy.

Actively managed compost attracts the type of microbes that raise the internal temperature of the pile to 140 degrees or higher and can be finished in as little as six weeks. This requires weekly turning and close attention to ingredient mixtures and moisture levels.

A more neglected pile will break down naturally but may take a year to produce finished compost and is likely to contain more weed seeds than a hot pile.

Compost needs four elements to work: carbon, nitrogen, air and water.

Carbon — the “browns” — can take the form of fallen leaves, straw, dried plant waste and shredded paper. Common sources of nitrogen — the “greens” — are grass clippings, fresh garden waste, kitchen scraps and coffee grounds.

It is essential to have a mixture of browns and greens, and composting experts write of an optimum ratio of 25 parts of carbon to one part nitrogen, but many ingredients already have those ratios built in. The key is to put in more brown stuff than green stuff. “We use three buckets of browns to one bucket of greens,” said Susan Eisendrath, coordinator of the compost display at the Master Gardener Demonstration Gardens at the agricultural history farm park in Derwood.

To increase the amount of air the pile gets, some compost recipes suggest placing the ingredients on top of a bottom layer of sticks and branches. The problem, however, is that these unwanted woody elements get incorporated into the pile when it is mixed. Eisendrath and her fellow Derwood compost gurus prefer to lay perforated four-inch drainage pipes before the pile is begun. You don’t need these, but they do speed the process.

The pile should be kept moist but not wet — shoot for the consistency of a wrung sponge. If it gets sodden, which is usually a product of a shady pile with too many greens, it will go anaerobic. A more common problem in hot Washington is a pile that dries out for lack of moisture, at which point the composting stalls. If that happens, add more greens and step up the watering.

Read: Compare composting bins

Below are some answers to common composting questions:


A compost heap (Bigstock)

How big should the pile be?

The optimum size is three to four feet in width, length and height, large enough to create a critical mass but small enough to turn. (Enclosed plastic bins tend to be smaller; see sidebar.) The volume will halve or more as the compost forms.

Do I need a bin?

No, nature composts without a bin, but a bin contains a pile more efficiently and establishes the compost pile as a feature of the garden.

Where should I place the bin?

Where it is convenient without being conspicuous. A bin in full sun will dry out more quickly, and one in deep shade may stay too wet.

What if I have far too many leaves for a single compost pile?

Use your lawn mower (a mulch mower is best) to shred leaves that have fallen on the lawn. The leaf shreds can be left and will quickly decay to the benefit of your lawn. Other surplus leaves can be stockpiled for future use in the compost pile. Shredded leaves can also be used to mulch ornamental beds, where they will break down, or as a winter mulch in vegetable beds, to be dug into the soil next spring.

Can I use material from outside sources?

Be careful of using off-site materials. Neighbors’ leaves may be all right, but grass clippings could be contaminated with herbicides that persist after composting and may harm garden plants. Avoid obviously diseased plants.

What about manure?

Horse manure with straw bedding is a good way to get an active pile “cooking,” but livestock manures come with a risk of pathogens such as E. coli and must be actively composted in a hot pile to minimize risks of contaminating the garden. You don’t need animal manures to make compost.

What about vermin?

Rats and other pests are drawn to certain materials that should be left out of any compost pile, including animal and dairy products, oils and sauces. Screened kitchen scraps should be buried deeply into a pile after mixing with brown material. Wholly contained bins are less attractive to scavenging animals. Some jurisdictions permit food waste only in enclosed, rodent-proof bins.

Should I chop material before adding it?

Shredding or chopping material first will hasten the composting process but is not necessary. Material that is too finely chopped may create a pile with too much moisture and not enough air.

Can I add weeds to the pile?

Weeds that have not gone to seed can be added to a passive pile, but it takes the heat of an active pile to cook weed seeds. Some gardeners put weeds in a closed trash bag for several weeks before adding them to a compost pile as, at that point, brown material.

Do I need an activator to get it started?

Not a commercial one — a little soil or existing compost will help to add desired microbes.

How do I know when it’s ready?

When it looks and smells like rich soil. At that point, cover it with a tarp for a couple of weeks to keep rain from leaching its beneficial elements while it “finishes.” Screening finished compost will produce an attractive soillike texture and remove remaining woody pieces, but it is not necessary.

I live in an apartment. What are my options?

Indoor red wiggler worm composting is an option, but this requires care and method to work properly. Some farmers markets also accept food scraps. An enterprise named Compost Cab collects compostable food scraps for a fee, and subscribers are entitled to finished compost. The business serves residents of the District and Maryland inside the Beltway and plans to expand to Northern Virginia in the near future, said owner Jeremy Brosowsky.

More from The Washington Post

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Gardening archive Read past columns by Higgins, including those on dahlias and pumpkins.