Finding rats or evidence of the pests in and around your compost bin can be more than a bit unsettling. These persistent rodents have been known to chew through wood, wire, plastic and just about anything else that gets in their way. They multiply at alarming rates; one pair can spawn nearly one thousand baby rats in a year, and they carry diseases. Whether you live in the city, suburbs or country, chances are you may end up having to deal with rats at some point.
In general, rats are looking for two basic things: food and shelter. In some cases, a compost pile ends up being both, and you have a rat problem. There are several simple ways to both prevent rats from getting into your compost pile and for getting them to leave if they've already found it.
Bury Food Scraps
Usually, rats are drawn to compost piles because they are easy sources of food. In general, you should never add meat or dairy to a compost pile because those items are a sure draw for rodents (there is an exception to this if you use Bokashi to ferment kitchen waste). If they're hungry enough, though, your potato peels might start to look pretty tempting. Whenever you add food scraps to the compost bin, either dig in a little and deposit your food waste inside, covering it up again when you've added it all or have a couple of inches worth of grass clippings or leaves set aside to layer on top of any food scraps you add.
Don't Add Food Waste
If rats are a real problem, and you don't want to have to think about it, forego adding food waste to your compost pile. Don't waste those valuable scraps, though. Set up a vermicomposting bin for food waste or bury it directly in the garden in compost trenches.
If you use Bokashi to deal with your kitchen waste, you are familiar with the odor fermented kitchen waste has. It turns out that even the hungriest rat steers clear of Bokashi fermented food waste. Throw your food waste into the Bokashi bucket, layer with the Bokashi bran, let it sit for two weeks, and then add the contents to your compost pile. It breaks down quickly, and rats won't even consider touching the stuff.
Keep Contents Moist
One of the two things rats are looking for when they invade your compost is a shelter. A dried-out compost pile not only is inefficient in terms of making compost, but it's a haven for rats. Just think: It's a dry, warm, insulated place to sleep that might have a few tasty morsels to snack on. If you make sure your compost pile is always moist throughout—not wet, which results in anaerobic conditions and unpleasant odors—it won't be a place rats will be interested in making their own. By turning the pile regularly and giving it a bit of water during dry spells, you can make it much less hospitable to rodents.
Plant Mint Nearby
This is one of those tips that seems to work for some people and not for others, but it's worth a try. Mice and rats are reputed to hate the scent of mint, so if you plant a few mint plants close to your compost pile, it may be enough to deter the little pests. However, if you have a very large or very hungry rat population in your area, it's unlikely that a little mint will deter them. By putting these tips to work in your compost bin or pile, you can ensure that it is a rodent-free zone.