A Heap of Nutrients

Thinking Inside The Compost Bin

At the New York Botanical Garden, from left, a three-bin system, a perforated trash can and the Earth Machine. (Photos By Ursula Chase -- New York Botanical Garden)

The act of compost making remains one of the small delights of life that can be achieved without reaching for a credit card. So far, it has not been homogenized, franchised or, for the most part, regulated.

You might argue, too, that it is not a small pleasure, but a rather great one.

Through the ages, gardeners have marveled at the process of gathering fallen leaves, garden greenery and maybe some livestock manure and watching the mixture heat up miraculously, to 130 degrees or more, and break down into a crumbly dirt that will invigorate whatever it touches. It converts heavy clay soil into free-draining but moisture-retentive loam; it brings nourishment as well as air and moisture to plant roots. More recently, gardeners have come to see its beneficial microbes as helping plants fend off pests and diseases.

Just as there are many approaches to compost making, there are many types of compost container. If there is one rule about composting, it is that some sort of enclosure or bin is better than a loose pile: The bin will hold more material more neatly, giving the pile the mass it needs to heat up and to declare to the world that this is something purposeful and not a dumping ground.

Even so, the sight of a compost bin can unnerve your neighbors, who fear it may smell and attract vermin. Compost piles can do both, but a well designed bin will keep out animals and, managed correctly, have no odor save a faint earthy aroma.

Compost bins fall into two basic areas: ready-made bins, usually of plastic and limited in size; and homemade versions that range from enclosures of humble snow fencing or poultry wire to formidable side-by-side, wood-framed bins that connote a gardener suffering from compost mania. The homemade versions look more natural to some, though others see them as scruffier than commercial versions and potentially more offensive to neighbors.

Cindy Brown, assistant manager of Green Spring Gardens Park in Alexandria, uses a familiar black plastic bin in her townhouse's back yard, which is more comforting to neighbors, she argues, especially those who mistake it for a garbage can. Plastic bins typically have enclosed tops and a small gate at the bottom, both useful for retaining moisture and keeping vermin away.

Many plastic versions are on the market, or can be fashioned from a small, round garbage can or even the large, squarer versions now used by most municipalities. Brown offers this critical advice: Drill lots of drainage holes in the bottom, or cut the bottom off entirely. A compost bin must drain to avoid a bacteriological meltdown. For the same reason, don't locate a bin in a part of the garden that remains waterlogged. You should also drill some side holes for air circulation.

But compost bins do need moisture to work -- the process comes to a halt when a pile dries out, which makes open-screened bins still viable, said Brown, as long as the gardener is willing to water them. A stalled, dried-out pile should be jump-started with water and with fresh material turned in.

Brown is not a fan of all plastic bins, though. She shows off a $25 bin consisting of two perforated sheets of black plastic bolted together to form a container approximately three feet high and two feet in diameter. "It is so thin-walled and has so many holes in it that in the summer it dries out incredibly and doesn't break down," she said.

Those of us who generate a lot of material -- with large wooded lots, expansive lawns or vegetable gardens -- typically need a commodious homemade bin to accept the larger quantities of grass clippings, fallen leaves, and spent tomato and melon vines.

In the demonstration vegetable garden at Green Spring, volunteers keep feeding a large bin handmade from robust, 2-by-12 planks stacked on edge and pegged with wooden posts. It measures approximately 12 feet long, 6 feet wide and 2 feet high. It is divided into two bins, one about twice as large as the other.