How to Compost, According to Gardening Experts

When it comes to composting, where things break down — or don’t — is often where we get in our own way. We make the whole process too hard by fixating on details instead of the big picture.

Yes, there are lists and rules that it’s tempting to get attached to: the precise ratio of high-carbon ingredients (often called “browns”) to high-nitrogen ones (“greens”), or achieving the ideal temperature for peak activity by particular bacteria and other decomposer organisms. Commercial composting operations rely on those rules, and the science behind them, to produce material that is consistent and meets regulatory guidelines.

We backyard composters can go a little easier on ourselves and still have great results, producing soil-improving bounty from our organic waste. The main mantra: Just do it.

“Become comfortable with decomposition as a natural act, one that will take place whether you are involved or not,” said Annie Novak, the manager of the Edible Academy at New York Botanical Garden. Ms. Novak, who is also the founder and director of Growing Chefs, a field-to-fork food-education program, lives in Greenpoint, Brooklyn, where she composts in her backyard, too.

Make like nature, the experts advise us: Pile up the organic matter and let time pass. Getting hung up on how long the process should take from start to finish or how many citrus peels are too many to add to the heap is going to make it all feel like too much.

“My rule is: Don’t worry about it,” said Cary Oshins, a longtime backyard composter who retired last month as the associate director of the U.S. Composting Council, an industry group. His current piles reside in Troy, N.Y.

As he put it, “Compost happens.”

Instead of worrying about whether you’re following all the rules, stick to some common-sense guidelines and have the right tools on hand. Ms. Novak, Mr. Oshins and others who have taught gardeners how to compost offered some advice.

You’ve tackled the spring cleanup to get the garden off to a fresh start. But were you as conscious about what kind of start all of that incoming material means on the receiving end — in the compost heap, bin or tumbler?

Any kind of organic matter will break down in time, but decomposition is fostered most effectively — and more quickly — when basic conditions are present. The pile should never be too moist or too dry, for example.

“You’re going for the moisture content of a wrung-out sponge,” Mr. Oshins said. “Not so wet that water runs down your hand if you squeeze it, but so you can feel the moisture — that it’s not dusty and dry.”

Also: Without worrying about the exact brown-to-green proportions, try to consciously incorporate both elements as you feed the pile. Anyone who has heaped up lawn clippings and then watched what happens knows the slimy, sloppy, smelly mess that results when you have too much green. Carbon-rich material, by comparison, tends to be drier and coarser, and slower to break down.

For better results, think about being more strategic when you’re gathering materials during future cleanups, especially in the fall, said Charles Dowding, an English market grower and the author of “No Dig: Nurture Your Soil to Grow Better Vegetables with Low Effort.” The popular organic, no-till practices he teaches rely on an annual top dressing of compost to keep the soil in prime condition.

Set aside some “browns” as you collect them to use during peak “greens” months in the active growing season, he suggested, when a lot of incoming organic matter is nitrogen-rich and will need balancing out. Stockpile small, twiggy trimmings, wood chips and dry leaves or straw for later duty. Cardboard and paper are good, too, but keep them dry until you’re ready to use them.

When you add material, he advised, think in layers, rather than piling on too much of any one element, brown or green.

Mr. Dowding, who uses a multi-bin composting system, likes to keep the material roughly flat-topped — not mountain-shaped, the way an open compost heap is inclined to become. It makes sense that it would be easier to layer alternating ingredients onto a somewhat level pile, and to keep the pile evenly moist.

And think loft, Mr. Oshins said: “If you’re a home composter, it’s really fluffiness you aim for. Do you have enough browns in there? And do you have enough food for the microbes to eat?”

Our role as composters is to be “microbe wranglers,” he said, “providing proper food and shelter for their micro-herd.”

The process of decomposition generates heat. In peak activity, commercial piles may cook along at 140 degrees or so. But “many home composting systems don’t have sufficient mass to reach temperatures” — between 90 and 140 degrees — “that really break stuff down effectively,” said Daryl Beyers, the author of “The New Gardener’s Handbook: Everything You Need to Know to Grow a Beautiful and Bountiful Garden.”

That is one reason that Mr. Beyers, who has taught the fundamentals of gardening at New York Botanical Garden for more than a decade, composts in three adjacent trenches, or pits, about 4 by 4 feet and 2 feet deep. Into them, he repeatedly layers “brown, green, soil” — the excavated soil he has reserved alongside the pit — until one pile is about a foot above grade. Then he starts filling up the next one.

“If you bury anything, it will rot,” he said — and, aesthetically, sunken heaps may blend into the landscape better than big, aboveground piles.

At home, and for his clients, he uses multiple composting stations, each with its own purpose.

A small, dual-chamber tumbler near the house makes an easy destination for kitchen scraps, which he mixes with the “brown” of shredded household paper or trimmings from adjacent garden beds. Bins or pits in the vegetable garden will be of service where the most material is usually generated. And an out-of-the-way pile can accommodate heavier yard debris that may take a couple of years to break down.

More mass can make for more heat and somewhat faster decomposition — but also more work.

“The bigger the pile, the more difficult it can get to aerate,” Ms. Novak said. “And an untended pile with too much wet, decomposing organic material can become anaerobic quickly.”

To make a hospitable environment for the hard-working microorganisms that do much of the decomposing, there is a balancing act needed between water and oxygen.

“Too much moisture, and the microbes don’t have enough air,” said Mr. Oshins. “Too little, and they don’t thrive.”

The usual prescription: Turn the heap. Mr. Dowding recommends doing that once a year. But this can be another point where home composters become overwhelmed.

“I think the operative word here is mixing more than turning,” Mr. Oshins said.

Ms. Novak’s favorite tool is a workaround to full-on turning. She calls the Tumbleweed Compost Aerator a “compost corkscrew” that “makes it easy to pop out big plugs of material and rotate the so-called browns and greens.”

While bending from the knees, she said, “rotate it into the pile — clockwise and then counterclockwise — and then pop it up like opening champagne.” Repeat the motion in other spots to “pull airspace into the pile,” she added.

Mr. Oshin’s mixing helpers: mail-order red wiggler worms (Eisenia fetida). “Worms do a great job at stirring things up,” he said. “They are much better turners than I am.”

But even with their help, certain bits may not break down. Mr. Oshins recently constructed a screen that fits over a wheelbarrow to sift his compost, for whenever he wants finer, more evenly textured material.

One more moment of reckoning that may put off home composters: when animals are attracted to the compost — especially to food waste.

This is another reason that tumblers, which prevent access, are great for kitchen scraps.

It also reinforces the importance of burying such waste in the heap, rather than tossing it on top. When you’re adding fresh scraps, use a garden fork to dig a hole to put them in. Then stir them a bit into the surrounding active compost before covering the stash.

The penlike wire bin that Mr. Oshins puts food waste in doesn’t keep rodents out, but it does exclude large animals like raccoons. He fashioned the 4-foot-diameter enclosure and its lid from wire fencing.

Ms. Novak has a tactic that outsmarts even the little guys.

“I will often let tastier leftovers break down in sealed five-gallon containers first before adding them to the compost,” she said. “Left alone, they ferment a bit into less-appetizing material — easily added to the compost pile, where it quickly ‘sweetens’ into good organic matter content.”

With the possible exception of diseased tomato plants, which go into the burn pile or the trash, Ms. Novak composts everything, she said: “For me, if it’s carbon-based, it’s going in the compost. That’s what happens when it’s left alone in real life, so why not in my compost pile?”

Weeks pass, and then months, and we ask anxiously: Is it compost yet? There is no precise timeline, because weather, seasonal temperature differences and the particular mix and volume of ingredients all affect decomposition rates.

It could be eight months, or a couple of years — but it’s always worth waiting.

Margaret Roach is the creator of the website and podcast A Way to Garden, and a book of the same name.

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