Stinky Compost? Here’s What to Do About It

Many people are put off by the idea of composting simply because of the notion that compost bins smell bad. This is true – compost can sometimes start to smell bad.

But this shouldn’t be the case.

When done right, compost should never smell bad. It’s important to understand the reasons behind why this happens and to know what steps you can take to stop your compost stinking.

Does Compost Stink?

First things first, does compost smell bad?

If your compost is well-balanced and taken care of properly, it shouldn’t smell.

Ideally, if everything is going well, compost should smell like earth. It should have the perfect balance of carbon, oxygen, water and nitrogen. However, when any of these are off-balance, you will have smelly issues with your compost pile.

Reasons for Smelly Compost

dumping compost in a bin

Compost generally starts to smell when the pile isn’t generating heat and the compost ingredients aren’t breaking down as they should. This can occur due to a number of reasons

1. Too Much Nitrogen

Why this happens: Too much nitrogen in your compost can cause the pile to become smelly. Green waste (the scraps produced in kitchen) is rich in nitrogen and can cause this imbalance to occur, so if you’re putting in a lot of kitchen refuse like celery leaves, lettuce and so on, you’d ideally want to cut back a little.

What to do about it: For optimal results, ensure that your compost pile is made of 20% to 50% green material (rich in nitrogen) and at least 50% brown material (rich in carbon). A good proportion is 33% green to 66% brown.

If you want to balance your compost pile’s nitrogen content, consider adding items like shredded newspaper and straw and mix it in thoroughly. Don’t forget to mix the green and the brown, as if the two are separated from each other in layers, it will start to smell bad as there will be an imbalance.

2. Wet Compost

Why this happens: This happens when your compost bin is placed in an area that’s wet and shady. A compost pile that’s too compact can also become damp and stinky. Too much moisture leads to decreased oxygen which, in turn, leads to smelly compost.

What to do about it: To avoid this, place your compost bin in a sunny area, that gets sunlight for around 8 hours per day. Also, give your compost a regular turn to increase air pockets and aeration.

3. Not Enough Aeration

Why this happens: If your compost is too compact, it will reduce the amount of oxygen in the pile and the number of aerobic bacteria will become depleted. This can result in a compost bin that smells like rotten eggs, as hydrogen sulfide is formed.

What to do about it: You should increase the air circulation in your compost pile by adding in some air pockets and regularly turning the pile. The bad smell should naturally die off.

4. Wrong Items in Compost

Why this happens: If your compost has items like dairy, oils, animal fat, meats and manure, needless to say, it will stink while these break down. What’s more, the compost can also attract maggots and other insects.

What to do about it: Keep non-plant matter from your compost bins. The odor just isn’t worth it. What’s more, compost with meat and dairy can harbor harmful bacteria. If you must add manure, either add it in small quantities, or cover it with up to 12 inches of items like shredded newspaper, peanut shells or straw to reduce the smell.

Check out our article on what to compost and what not to to help you figure out how to keep your bin smell-free.

4. Insufficient Heat and Microbes

Why this happens: Compost works if there are microbes that break down the organic matter. However, if there isn’t sufficient heat, the microbes won’t be able to thrive and will become depleted.

What to do about it: A good temperature is around 70 degrees Fahrenheit (or 21 degrees Celsius). Ensure that your compost has just the right amount of water to help the microbes thrive and sufficient sunlight to get them going.

Choosing the Right Compost Bin

compost tumbler
Tumbling Composter by FCMP Outdoor. See it here.

The type of compost bin you choose will also contribute to whether or not there are any bad smells.

Tumbling compost bins are designed so that they can easily be turned, which increases aeration, properly mixes the pile and speeds up composting. This takes the compost items from a state of refuse to turning to dirt much quicker.

Tumbling composters, like the one featured above which has thousands of 5-star ratings, are often the best options when choosing a composter with minimal bad smells.

Tips to Keep Your Compost from Stinking

We’ve already discussed these in detail above, but here’s a summary. These general rules should eliminate issues that you can have with compost.

  • Mix green and brown waste (ideally 33% to 66% respectively) and don’t layer. This ensures a good balance.
  • Turn or tumble your compost regularly, at least once a week.
  • Chop your compost into small pieces. This helps it break down faster.
  • Maintain optimal temperatures for the compost.
  • Ensure there’s sufficient sunlight and water.

Troubleshooting a Stinky Compost Bin

  1. What if my compost pile smells like rotten eggs? This simply means that there’s not enough air in the pile, caused by an overly compacted bin.
  2. Why is there a strong smell of ammonia coming from my compost bin? This happens when there’s too much nitrogen in the compost. Aerate the compost, tumble it frequently and add more brown materials to it to balance out the excess nitrogen. 
  3. How can I increase the microbial life in my bin? Keep your compost bin at optimal temperatures (around 70oF or 21oC or above). Keep it moist to help the microbes thrive.
  4. There aren’t enough microbes in my compost bin and it’s starting to smell. You can add some soil from your garden into the compost, as this has microbes which can grow in the right conditions in the bin. You can also buy a compost starter like this one to give the compost a boost of microbes.
  5. What items shouldn’t I put in my compost bin? Avoid animal products like dairy, meat, fish, animal fat, oils and manure. These tend to stink and require more advanced composting skills.

Wrapping Up

If your compost bin is well-balanced and properly taken care of, it shouldn’t smell bad. Bad smells in a compost bin are an indication that something isn’t quite right.

Check the bin to ensure that the moisture, air, nitrogen and carbon are at optimal levels. Also, choose a composter that’s easy to tumble and mix, as this will speed up the composting process and help to maintain an optimal environment for compost.