QUESTION: Should a compost bin have a lid? – DJ F
ANSWER: Having a lid on your compost is not a requirement, but it does help you to regulate and maintain temperature and moisture levels within your compost system. If your compost bin doesn’t have a lid, you can add your own by using a piece of old, Hessian backed carpet (not foam-backed carpet to function as a lid. A cover is also preferable because finished compost needs to be covered at all times, as it will break down and lose nutrients if it is exposed to the elements.
Other reasons to cover your compost is to protect your heap from receiving too much rainfall, which can waterlog the compost, which creates a lack of airflow in your pile, causing your compost to become slimy and stinky. A covered pile helps deter insects, rodents, and other pests from digging around in your compost.
A covered pile is also easier to heat up to compost’s ideal temperature range, and heating up your pile can make your compost decompose much faster than usual, taking weeks, even months off of the time it takes to process your compost normally. Hot compost is also able to kill weed seeds and harmful garden pests. Covering your compost also keeps it processing during the winter, instead of becoming dormant when the weather starts to freeze.
The best lids for compost bins are raised to create a pocket of air on top of the compost. Plywood is a good option for a cover material, as it allows air and moisture to pass through it. The lid should never rest on top of the composted materials, but should rest on the frame that holds the compost. A piece of old carpet or a tarp held down with a few stones can make sufficient compost pin covers, however, a tight tarp that rests firmly against the top of the pile could restrict airflow and rainfall, leading to a smelly, mold covered compost pile.
If you live in an area that gets lots of rainfall, place your compost bin underneath an overhang so that it gets a little less rain. You don’t want a lot of rain getting into your compost, and placing your bin just under the overhang of a garage, shed, or house can help keep a good amount of rain out of your bin. On occasion, move your bin out into the open during a little light rainfall to get a good soaking, but be sure not to let the mix get too wet though. Your compost should always feel slightly moist when you squeeze it, like a wrung out sponge.
Paint the lid of your compost bin black or a very dark blue or brown, as dark colors help draw in sunlight and will help heat up your compost pile. In the winter months, insulate your compost system by covering your bin in straw bales, or adding a wooden lid to help keep your compost from slowing down in the winter.
Plenty of compost piles decompose fine without coverings, and though the process might take a little longer, it is perfectly okay for you to leave your compost pile uncovered. Whether or not you cover your compost should depend on your goals, the region you live in, and the type of composting system you are using.