Why do Compost Bins Smell? Good Composting 

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Last Updated on January 25, 2023

Why do compost bins smell? Is it possible to reduce the smell that emanates from your compost bin? 

Yes! With the right composting practice, you can keep your compost bins from stinking like a decomposing animal. 

While composting is a good gardening practice, a compost pile can very much turn your garden to a smelly yard; something every responsible gardener tries to avoid. Composting is a simple practice that can be as easy as taking out the trash. But it can be a whole lot difficult when the pile begins to stink and is almost impossible to keep the stink down. 

You can compost almost anything that comes out of your kitchen. Leftover vegetables, fruits, food pieces, decomposing food, grass clippings, and any other thing you feel can be used as nutrients for your plants. 

Most of the things we throw into the compost bin or pile will eventually begin to decay after a few days (or weeks). Once decay sets in, the compost pile begins to give off a pungent smell due to the activities of the micro-organism that builds up inside the pile. 

While you can’t stop the activity of the micro-organisms, you can control the amount of stench that comes out of your compost. 

Before I share with you a few good composting practices, let us first take a look at some of the reasons why your compost bin is giving off a strong stench. 

The Compost is Too Compacted

When you pack your compost too tightly, it can make it difficult for air to circulate around the pile. Without enough oxygen in the pile, it becomes difficult for the micro-organisms to perform their function – which is to break down the compost. Without air, the bacteria cannot populate to speed up decomposition. The bacterium that is left in the pile begins to give off a foul smell that results in a smelly backyard or garden. 

You need the microbes to settle properly into the compost pile so you need to ensure they have enough room to stay in. For your compost to be properly ventilated, you will need to ensure that you place it in an area where it can get enough ventilation. Avoid keeping the compost in a shady or damp area. Also, you want to ensure that there is enough space between piles to allow air to circulate. Too much of dense materials on top of each other will make it difficult for air to enter into the heart of things. 

You can use a rake or pitchfork to turn the compost pile regularly to free up things inside the pile. This also helps to expose the bottom of the pile to some fresh air. This helps to reduce the smell when performed regularly. 

Wet Compost Smells the Worst 

When there is too much water in your compost, it can cause the pile to smell. More than when your compost is dry. For your compost to decay properly, it will have to be left outdoors under the sun, rain, and wind. These are three elements that are important for composting to take place. However, when there is an excess of any of the elements, it can affect the procedure negatively. 

Too much water in your compost will make it difficult for the bacteria to get to work, and cause your backyard to smell. To drain excess water from your compost, you will need to keep it in an area where it can get direct access to sunlight. You should make it a habit of turning the compost pile once a week. This can help to circulate air and heat around the pile to keep the stench down. 

Wrong Composting Materials


Another reason why your compost smells so bad is because there are materials in the pile that aren’t supposed to be in there. Materials such as dairy products, meats, animal fat, and oils are not supposed to be a part of your compost pile. 

The best rule to follow when placing materials in your compost pile is to make use of plant-based materials. This can seriously keep your compost bins from smelling. It also keeps dogs, cats, raccoons, and other rodents from sniffing out your compost bin. 

Not Balancing the Greens and Browns 

One of the best composting practices you need to follow to ensure your compost is rich is to use the right ratio of green and brown materials. Green materials are rich in nitrogen and include green leafy vegetables, and grass clippings; while the brown materials are rich in carbon and include straws and shredded newspaper. 

When the green material in your compost is more than the browns, your compost smells like ammonia. This is a sign that you need to include more shredded newspaper, brown leaves, straw, and pine needles, to balance things out. 

Layer your materials evenly, and don’t forget to use a rake to turn the compost once a week to allow for air and heat to get circulated around the pile. 


Can compost bins smell?

Compost bins can stink. This is a fact. The reason for the smell is that there are some bacteria in the bin that feed on the carbon and nitrogen in the food waste. The waste produces a gas, called methane, which smells of rotting meat. It also produces ammonia which can cause a skin rash and eye irritation. What should you do if you find your compost bin stinking? The best thing to do is to seal the compost bin with a lid. This will stop the air getting into the bin and it will help keep the smell down. If you don't have a lid, try putting some charcoal in the bottom of the bin. This will help absorb the methane gas before it gets into the atmosphere.

What do they smell like?

The smell of compost is often compared to that of a flower garden, and for good reason. The essential oils released by plants during decomposition are very strong, and the same goes for compost. However, the odor is usually not noticeable until it gets going.

Most compost bins should smell like a mixture of decaying leaves, grass clippings and soil. If it smells different, there is likely something wrong with your bin. If the bin smells like a combination of rotten eggs and ammonia, you might have a problem with too much nitrogen in the mix.

Ammonia is a byproduct of decomposition that has a pungent odor. If you have too much nitrogen in your compost, you will likely see lots of green algae growing.

What determines the strength of the stink?

You may be wondering what the smell is that emanates from your bin. There are many factors that can affect the smell of your compost, and this can range from how much food you throw into the bin to how the temperature of the bin is set.

The type of compost bin you use, what you are composting and how long you have left your compost to decompose are also important factors.

How do I control the smell in my compost bin?

The first you can try is to get some air circulation. The easiest way to do this is to use a fan. I have one that runs on a small electric motor, and it makes a great breeze.

It takes up very little space and only needs to be plugged in when you use it. You can also try turning the pile occasionally, which helps to aerate it as well. You may have read that a number of people use borax in their compost bins. It is widely available and inexpensive and you may even find it at your local garden centre. Borax is an alkaline compound and will raise the pH of your compost.

How to Keep Compost From Smelling

A smelly compost pile can ruin anyone’s day. Luckily, you can do a few things to prevent this from happening to yours. Here are some tips you can follow to create rich, healthy soil for your garden without a foul smell:

  1. Use a mixture of brown and green materials in your compost pile. Brown materials like dry leaves and straw provide carbon. Green materials like grass clippings and kitchen scraps provide nitrogen. A balance of these will prevent odors. 
  2. Keep your compost pile moist, but do not overwater it. If the pile is too dry, it may not decompose properly. This could lead to a bad smell. If it’s too wet, the compost can become anaerobic. This can also lead to unpleasant odors. 
  3. Turn your compost pile regularly. Aerating the pile helps oxygenate it and prevent odors from developing. You can turn the pile with a compost aerator or use a pitchfork. Keeping your compost pile in a well-ventilated area will also help. 
  4. Always add a layer of soil, finished compost, or other organic matter to the top of your compost heap. Doing this will help speed up the decomposition process and can prevent odors. 
  5. Never add meat, dairy, or oily foods to your compost pile. These types of food can attract pests and cause a pile to smell. 

Compost Odour Control: What to Do If Your Compost Heap Smells

There are several ways to control odors in a compost pile:

Maintain a Balance: If you have more green or brown material in your compost pile, add more of the one lacking. 

Use a Compost Activator or Inoculant: An activator or inoculant can introduce beneficial microorganisms to your compost pile. These can break down the organic matter and reduce odors. 

Cover Your Compost Pile: Cover your compost heap with a tarp or other cover to help retain moisture and heat. This will speed up decomposition and reduce odors. 

What to Do If Your Compost Smells Like Ammonia

If your compost heap smells like ammonia, it may indicate that your pile is too wet and has become anaerobic. Anaerobic conditions cause the breakdown of organic matter to produce ammonia as a byproduct. 

Here are a few things you can do to fix this problem:

Add dry materials: Mixing dry materials like leaves and straw into your compost heap can help absorb the excess moisture and improve the smell. 

Add Lime: Adding a small amount of lime (calcium carbonate) to your compost pile can help neutralize the ammonia and reduce the smell. 

Add Fresh Air: Aerating your compost pile will allow fresh air to circulate. This will improve oxygenation and reduce anaerobic conditions. 

Compost Too Wet and Smells: How to Fix It

If your compost is too wet and has a smell, there are a few things you can do to fix this problem:

  1. Start by monitoring the drainage of your compost pile. Ensure the pile is on a well-draining surface and that any water collecting around the base can drain away. 
  2. Turn the pile to improve oxygenation and distribute the moisture evenly. 
  3. Check the moisture level regularly to ensure your compost pile is moist but not soggy.
  4. Add dry materials to absorb excess moisture.

By following these steps, you can remedy a too-wet and smelly compost pile to create rich, organic matter. 

Lack of Microorganisms

Like we mentioned earlier, your compost needs the right population of microorganisms for breakdown to take place. When the population isn’t enough to support decay, the compost pile won’t heat up and begins to give off a foul stench. 

You can support the growth of microorganisms in your compost by placing the compost bin on the ground. You can also speed things up by introducing organic soil or fresh compost to your bin. This will lead to the speedy formation of microorganisms and leads to a quick decomposition of your compost. 

With the right composting practice, your compost pile shouldn’t smell. This you can encourage by simply 

  • Ensuring that the compost isn’t compacted. 
  • Keep the compost in an area where it can get direct access to sun, rain, and air. 
  • Place your compost bin on the ground.
  • Use the right composting materials.
  • Balance the ratio of green and brown materials in the composting pile. 
  • Use a lid to cover your compost bin when it rains heavily. 

How do you keep your compost from smelling? We will like to hear from you in the comment section. 

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