There are many ways to compost, but one of the most popular methods is using a compost bin. Compost bins are simple structures that let you turn your organic waste into nutrient-rich soil. Compost needs heat, is it possible for it to get too hot?
A compost bin can get too hot. If your compost bin overheats, it might damage the compost, especially if you have vermicompost. The overheating temperature varies depending on the type of compost.
Below, I’ll go over the ideal conditions for your compost bin and when you should start to worry. We’ll talk about ways to cool down your bin, common causes for overheating, and strategies for keeping your bin at the right temperature. I’ll also discuss the specifications for your vermicomposting bin.
Ideal Temperature Conditions for a Compost Bin
Overheating isn’t a good thing for compost. It needs to be kept at a specific temperature for it to break down properly. Too cold and the microbes that make your compost will slow down; too hot, and they’ll die off altogether!
The ideal temperature for your compost bin is between 60 and 160°F (16 and 71°C). So how hot is too hot? Between 160-170°F (65-77°C), your compost may begin to lose microorganisms that are meant to help strengthen and nurture your soil.
It’s important if you live in a warm climate not to just take the daily temperature as an indicator of how hot your compost bin is. There’s a chance that depending on the material you use, and the location of your compost bin, the compost inside is double the temperature of the outside world. This is why you can’t leave kids or dogs in cars even if the temperature is mild—the inside of the car overheats way beyond that point.
On the flip side, if you live in a cold climate, ensure that your compost pile isn’t too cold. Your compost may freeze over and not be able to do the important work you intended for your garden.
What Happens When a Compost Bin Gets Too Hot
When a compost bin gets too hot, the microbes within your compost may die out. This is most prevalent if you’re using vermicomposting—it’s easier to understand that wiggling worms may get too hot and feel sick, be too overheated to work, or even die. Even without worms, small organisms operate within your compost, and they need a specific ideal temperature to work.
It’s the same on the cold days of winter, too. This is why you should never put ice cubes in your compost bin: they will lower the temperature of the whole system and kill off or send into dormancy those helpful microbes. It’s also why you shouldn’t pour boiling water over your pile if it gets too cold: the heat from this super-hot liquid can kill off these microscopic critters before they have time to do their job!
Common Causes of Compost Bin Overheating
It’s not uncommon for compost bins to overheat, especially if you live in a warmer climate. Besides just living in a hotter area, there are a few things that might be causing your compost bin to get so hot.
- Your compost pile is too big. Compost piles that are too large for your available space will not heat up as much. This can be detrimental to the entire process, and you may need to split up the pile or find a larger container if this happens to you.
- Your compost pile is in the wrong container. Containers that are very translucent or attract more sunlight without supportive insulation will likely heat your compost pile more quickly.
- The level of moisture in your compost pile isn’t right. Temperature increases with humidity levels, so if there isn’t enough moisture in your bin yet (and therefore no evaporation), less heat will be generated. Make sure there are plenty of damp layers throughout before turning over any material. Then, keep adding more water after each addition cycle until it feels juicy rather than dry when squeezed between two fingers.
- Your compost pile is in the wrong spot. If you’re used to gardening, you may know there’s a difference between partial and full shade areas. You don’t need to necessarily have your compost pile in the shade, but you should be sure that your compost pile isn’t in a spot that’s hotter than the rest of the garden. Reflective materials such as cars can create hot spots, and a little shade might be good if your compost is exposed to a lot of heat.
Additionally, pay attention to the size of your container compared to how much compost you have. If you’re putting a ton of compost in a really small space, then you will likely have overcrowding and heat issues.
On the flip side, small amounts of compost in a big container are spread more evenly, which means it will get more sun. In this case, you’ll want to add plenty of moisture.
How To Keep Your Compost Bin at the Ideal Temperature
The best way to keep your compost bin at the ideal temperature—besides being mindful of the common causes of overheating—is to use a thermometer and tumbler.
A thermometer allows you to measure the temperature accurately, and a compost tumbler will ensure that everything stays in motion.
Using a thermometer is easy and inexpensive and will give you an easy indicator of when your compost is getting too hot. If you go online, many compost bins will have a thermometer attached to them so you can be mindful of the heat. However, using a regular thermometer or even a meat thermometer works, and you can build it into your current system.
Tumblers are often expensive–luckily, they’re not required–but it may be worth it if you’re composting large amounts.
How To Cool Down an Overheated Compost Bin
If your compost bin is overheating, here’s what you can do:
- Turn the compost bin over. If it’s really hot there, your decomposition process may have accelerated so much that the insides of your bin are now too hot for healthy composting. To fix this problem and allow oxygenated air to circulate again, turn your composter over so that its contents drain into a cooler area—such as an open field or lawn. Then you can regather it.
- Open up a hole in the top with a hammer and chisel. This will help cool air get back into your system and prevent further overheating while allowing excess heat to escape. Be careful not to damage the bucket when doing this. If you break off any part of it while trying to pry open one side or another, just use some duct tape or super glue to patch it.
- Move it into the shade. If it seems like your compost bin is getting too much heat outside, you can take it into the shade.
- Mix the contents of your bin. Things at the bottom of your bin are likely cooler, so mixing things up can help even out the temperature. The layer on top is typically the warmest.
If you seem to be doing everything in your power to support your compost bin, and it’s just not working, you may decide it’s time to look into a different bin material or buy one of the bins sold online specifically for compost purposes.
Temperature Differences in Vermicomposting vs. Composting
Vermicomposting is a method of composting that uses worms to break down organic matter. It’s more complicated than traditional composting but also more effective.
When you add food scraps to your bin, you’ll need to aerate the mixture regularly and add water as needed. You should be even more cautious about temperature when vermicomposting because if the interior of your bin gets too hot, it can kill off all those cute little critters in there!
Bins are considered “too hot” for vermicomposting at around 80°F (26.67°C). At this point, your worms may become sluggish and have a harder time doing their job. Make sure your worms don’t bake in the sun.
For more details, you could read my other article here: Vermicomposting vs. Composting – Differences Explained
Composting is an easy way to add nutrients to any garden, but you must know exactly how to keep your garden in tip-top shape so that your plants can flourish. If your compost bin gets too hot or too cold, it could affect your plants’ health (or even kill them).
Hopefully, this article has taught you what causes temperatures outside the ideal range so that next time something like this happens, you’ll be able to fix it quickly.
To learn more about composting with and without a bin, you could check out: How to Compost With and Without a Bin (Ultimate Guide)