Smelly Compost? How to Control Bad Smell on Your Compost

Gisela Possetto 2021-06-30 7 min

Has your compost started to get smelly? You probably know by now that bad smell and how to control it are common concerns among the Compost community. Sometimes your mixture can stink... but don't worry, we'll give you some tips!

Composting has many benefits: you can recycle your own waste at home -or at least part of it- which means less tons of waste in landfills. So, basically, making your compost is great for the environment and also for your plants and flowers there in your garden or balcony!

But not only indoor compost can smell.The pile of compost out there in your garden or yard can start to stink as well. But why does this happen? Aren't compost supposed to smell? You'll find out in this article some basics about compost, what the "good" smell of a compost should be and what to do if you are already having composting problems.

compost soil
Compost Soil - Pexels

Compost Basics

First things first, in case you haven't read our articles on compost, please do. In Here is the complete Guide on how to Composting at Home, you'll find the most practical ABC tips to start composting at home. But just in case you have no idea about composting at ALL, do not worry, you've come to the right place (at least we hope so...)

A. What is Composting?

Composting is the process through which organic matter breaks down into highly nutrient-rich soil (or humus). Organic waste includes pretty much any waste from your kitchen, leftover food, flowers and leaves.

B. What do I need to get started?

Composting at home is absolutely a great idea and the planet will very much appreciate it, for sure.

To begin with, you'll need some sort of container — it could be a pot or a plastic bucket in which you should make holes for an optimum air circulation.

Twice a day or so, collect all green and brown waste from around the kitchen and garden or balcony and drop it into the container you chose. Try to cut peels and alike greens into small pieces so that they decompose easier in the pile. Once you have your "greens", it's time to cover them with your "browns".

Keep doing this until the pot fills up. Stir the mixture every a couple of days to add the right amount of air. It's very important that your compost pot is closed - not sealed, though- so that, with due time, everything starts to settle. After some weeks - it usually takes six to eight weeks- you'll open your pot to see that the waste now smells like damp earth, or at least that should happen.

compostabe bag filled with red apples
Bio Compostable Bags - Unsplash

C. Compost Ratio

Although the magic recipe for a good compost does not exist, there is something that is key to a good compost and that is compost ratio. Compost ratio refers to the right balance that has to exist between greens and browns in your compost for this one to be a success:

đŸŸ¢ Greens such as leaves, grass or even food scraps are organic materials with a high level of nitrogen.

đŸŸ¤ Browns are for example, paper, wood chips or stalks and these are rich in carbon since they come from wood.

For the process of composting to start, the right combination of greens and browns is crucial. This is technically called Compost Ratio, and you can learn a lot about this by reading our article The Perfect Compost Ratio: Greens to Brown Balance.

Composting Problems

Alright, so far we've referred only to the bright side of composting, so to speak. But it might be the case that your first couple of times, you compost pile may smell badly. The most common reason for this is that the compost ratio is off. Probably you have too many greens or too many browns. Maybe the air circulation is failing or the temperature or humidity might not be adequate.

All of the above alters the natural balance of a compost, and thus, it might eventually become a smelly pile of waste. And no one wants bad smells at home, right? So let's check some important information that might help you know more about how to avoid a smelly pile of compost -or sort this out in case you already have it!

For a complete guide to troubleshooting compost problems, please read our article Composting Problems Types and How to Deal with Them. We'll be paying more attention this type of what to do if you already have a smelly compost. Let's see...

compost bin with signs in German
Compost Postal - Unsplash

Should compost smell?

The answer is yes, but it shouldn't smell BADLY! First thing to acknowledge is that a fresh, good compost should smell like soil smells before it rains or something of the sort. The "good" smell of a compost is that of damp soil. If it is not, something wrong is going on and thus, your compost pile is not heating up and breaking down the organic material in a proper manner.

So let's check now on some practical tips for you to get rid of that awful smell and prevent this from happening again!

1. Avoid this into your compost

  • coconut shells
  • mango seeds and
  • peanut shells

These take too long to decompose, almost a year. If the shell is too thick or the size too big and cannot be chopped smaller, leave it out. If you put these to the mixture, they will block the air entrance and it will start to stink.

Dairy products,as well, are not recommended as they attracts rodents. Avoid bones, too. They take too long. An alternative to crushed eggshells -which are are a great source of calcium- can be added directly to the soil or in the form of tea or dregs as a fertilizer. For a more complete list, check on Compost 101: A Complete List of What Items Cannot Be Composted.

2. Check that you are not layering

Layering is not good for your compost pile. It's very common that a compost pile has the right balance of greens and browns but they have been put into the pile in layers. Layering is a problems because basically, the greens cannot break down correctly with an unbreakable shield of carbon on top of it. Besides, it will start to give off a bad smell.

It is true that this is everybody's mistake at first and fortunately it is simple to correct! Start by airing and mixing your pile better and more often, and please bear in mind not to layer too tight next time!

leaves and fruits on black surface
Greens & Browns - Unplash

3. Too much humidity

It is often the case that in the spring or warmer days, you will notice that your compost stinks. This is so because rains are more common during warmer seasons and thus, your compost pile will get too wet. An excessive amount of humidity will give no room for air to come and go.

Think of compacted soil, but in your pile. The effect is the same: a smell of putrefaction or rotting and it will look soggy or slimy at sight. These are not good signs! What can you do? Simple, keep a closer eye on your compost during these days; and if you see that it's too wet you can add dry brown materials to absorb the moisture.

4. Too many greens

This is another common mistake we usually commit at first when composting. If you have too much green organics in your compost pile, the smell will be awful. It will be like sewage or ammonia. This is an indicator that the balance of your greens and browns is completely off. But do not worry, with patience and dedication you can patch this all up. Try adding brown materials like leaves, newspaper and straw so that the greens start to be outbalanced.

5. Your compost heap is compacted

Always keep in mind that good air circulation is key to a good compost. Compost piles need air, oxygen to break down the organic material properly. If there is no oxygen, a smell of rotting eggs will spread all over. That means that your greens and browns are off balance and decomposing wrongly.

maple leaf on brown dried leaves
Browns are allies! - Unsplash

One thing you can try is turning the compost pile to help air get into the compost and prevent further bad smell from emerging. Remember, as well, that you need to move your compost pile often so that the natural process of decomposing properly can take place. So stir your heap quite often.

One more tip, next time you drop stuff into the compost pile, please check that you add a soft layer of browns like leaves or dry grass to prevent compacting from happening again.

Let's re cap!

So dear Compost Warrior, if you are having some sort of bad smell trouble with your compost, do not give up! Keep in mind that this is usually because of some sort of unbalance among the elements that account for a good compost: green and browns in the right amount and shape, good air circulation and the right amount of moisture.

If you can spot the problem, first you'll know better how to fix it. Hope we've contributed some useful information to you in that sense! Keep and eye on your compost and see you around!

Gisela Possetto

Copywirter, Cats + Tattoos + Music Lover

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