How Wet Should I Keep My Compost Pile?

Keep your compost damp, but not wet, to encourage rapid decomposition.
i Doug Pensinger/Getty Images Sport/Getty Images

Decomposition in compost piles is an inexact science. Given time, all organic materials break down, assuming they are exposed to air and moisture. Ideal compost conditions, however, encourage the growth of microorganisms, which facilitate rapid decomposition. According to the Department of Agriculture's National Resources Conservation Service, compost piles function best at the approximate moisture level of a wrung-out sponge (see References 1).

Indications of Too Much Moisture

In compost piles with too much moisture, microbial activity is slow, resulting in little decomposition. Such piles have strong odors and thereby attract flies, resulting in maggots. The odor is a result of disproportionate activity by methane-producing organisms that thrive under wet conditions (see References 2, pages 1 and 2). Overly wet compost may also encourage the growth of mold.

Indications of Too Little Moisture

In compost piles without adequate moisture, decomposition is slow or may appear not to be happening at all (see References 2, page 2). Compost ingredients may blow away in the wind, and the outside of the pile may become hard and crust over.

Composting in Wet Climates

In climates with high levels of annual rainfall, take care to provide compost piles with adequate drainage and aeration. Start piles atop branches and other woody material to allow rain to run out the bottom. Contain piles with permeable material, such as chicken wire, instead of wood. If you live in an area with daily, soaking rain, build a cover over your pile or keep your compost material in a closed container. Turn piles often to ensure the proper balance of moisture and aeration (see References 3). Add moisture-wicking organic matter, such as wood chips, to draw moisture from the pile.

Composting in Dry Climates

Water your compost pile frequently if you're in a hot, dry climate. Turn the compost when you water to ensure even coverage. Build piles in the shade or under adequate protection from direct sun, as internal temperatures over 160 degrees Fahrenheit will kill microorganisms and stop the decomposition process (see References 2). Double- or triple-bin systems allow for ease in turning by transferring the contents of the pile from one bin section to the next.

the nest