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Can You Compost Onions?: Tips For Adding Onions To Compost

by Idris Ya'u
This article was fact checked.
Helpful: 100%

Despite some issues that were raised on onions with regard to adding them in compost, the short answer to this question is yes, you can compost onions.

However, there are some conditions that you need to take if you want to safely compost the onions.

Keep reading to find out.

Can you Compost Onions?

Composting is one of the easiest and cheapest ways to get rich organic fertilizer full of nutrients, which are essentially required by plants for healthy growth and yields.

Another good thing about composting is you manage the amount of waste you send to the trash. This helps keep the surrounding clean and waste-free.

Some of the kitchen and garden waste can be composted so easily while others can only be composted when you employ some composting techniques. While others even with proper composting maintenance and preparation do not yield a good compost and in some cases, they may end up damaging the compost or cause serious damage to the plants that will be fertilized with this compost.

Onion is one of these organic matters that can only be added to the compost if you take the proper composting maintenance and preparation.

Some of the problems that onions may cause when added to the compost is releasing of unpleasant odour. Onions and garlic are very odorous, especially when they begin to rot. And this bad-smelling may disturb the neighbouring people and any random visitor.

Additionally, this unpleasant odour can attract pests such as rodents. And they can come to your compost bin and mess up with any effort that you put in making the compost.

However, the above issues should not be of concern if you can follow the following composting preparation and maintenance:

Do not add plenty of onions in the compost bin: adding too many onions to your compost can make onions overweigh any compostable material in the compost bin. So, avoid adding too much onions.

Cut the onions into pieces: do not add the onions in large sizes. Cut them into smaller pieces before adding. This cutting can help increase the surface area, which males it easy for the decomposition microorganisms to break down the onions so quickly.

Add more browns: browns are compostable materials that contain more of carbon. They also have the ability to absorb moisture from other substances.

Browns include shredded newspapers, sawdust, chopped cardboard, and shredded straw and hay.

So, add brown organic materials so that they can absorb the moisture from the onions. And this helps prevent your compost to release unpleasant odour.

Place the onions deep down the compost bin: the bottom and middle of the compost bin is more hotter than the rest of the compost. So, adding onions to these parts of a compost bin can help speed up the breakdown of onions and so prevent the onions from releasing a bad odor.

Learn more about onions in compost

How to Compost Onions

Here is step by step guide on how yo compost onions:

Prepare your compost bin: get your compost container ready for the composting. A good compost bin should have holes on the sides, bottom, and top of lid. These holes are required for movement of air in and out of the compost bin.

If the compost bin do not have these holes, create them using a screwdriver or drilling machine. Create about 5 holes on the lid, 5 holes on the bottom, and 10 holes on the sides of the compost bin.

Place the compost in a suitable place: find a good place in your backyard that is flat and in the sun’s direction. This is important because when you place your compost bin on a spot that is flat, your compost will be falling down every time.

Moreover, placing the compost bin in the sun’s direction will make the compost generate more heat when heated by the sun. And this can help speed up the composting process.

Add browns: you need to first add brown compostable materials to the compost bin. Browns include chopped straw and hay, sawdust, and shredded newspapers. Add these types of compostable materials to the first layer. You need about 5 inches of browns.

Add garden soil: follow the browns layer with a layer of garden soil. This soil can increase aeration and also bring in other decomposition microorganisms such as earthworms.

Add the onions scraps + other greens: before adding the onions to the compost, mix them with other greens such as banana peels, pineapple peels, coffee grounds, and grass clippings. Before mixing with the greens, ensure that you chop the onions into pieces. Then, mix them up with the greens. Add them into the compost bin. You need to put about 5 inches of this mixture to the compost bin.

Alternate between browns and greens: you need to continue adding browns and greens in an alternate layer until the compost bin is full.

Browns> onions scraps+other greens> browns> onions+other greens

You need to alternate between browns and greens as I described above.

Make sure you concentrate your onions scraps in the center of the compost bin and stop adding onions scraps add only greens when the composting materials reach about 2/3 of the compost bin.

Turn the compost timely: when the compost bin is full, cover it with a lid. Watch for any pests especially rodents. If you see them, that is an indication your compost is smelling. In this case, you need to add some chopped straw, shredded newspapers, or sawdust.

Additionally, after 2 weeks or a month, start turning the compost form time to time. This can also helps increase air passage and also generate heat that will speed up the composting process.

Also read: Can You Compost Paper Towels?: The Detailed Guide To Paper Towels Composting

How long does it take for onions to decompose

If you chopped the onions very well, your compost will not take a long period of time. However, it also depends on what other compostable materials you put into the compost. For instance, if you add avocado peels or unshredded wood, your compost may also tame a long period of time.

Other important factors that determine how long compost will take is the type of composting method you employed. Cold method of composting usually takes longer time while hot composting method usually takes short period of time, which is usually 3-6 months.

The method explained above is a hot method of composting. In this case, if you follow everything step by step as I explained above, your compost can be completed in about 3 months or 6 months.

Read also: Composting Pine Needles: The Detailed Guide

Frequently Asked Questions

What should you not Compost?

The common households waste that cannot be composted are fish scraps, meat scraps, dairy products, and so on. They are materials, which are usually avoided not because they cannot be decomposed but because they can damage the entire compost or affects the quality of soil and plants’ health.

Read also: How To Shred Cardboard For Compost

Can you Compost Citrus and Onions?

Citrus can be added to the compost but with caution. This is because the essential oils in citrus peels can kill the decomposition microorganisms that are present in the compost.

Tip: You can learn more about citrus peels composting here

Can you Compost Garlic?

Garlic is just like onions. Garlic can be composted when proper composting maintenance and preparation are taken such as cutting the bin into pieces, adding a small amount of garlic to the compost bin, and timely turning of the compost.

Should I pee on my Compost Pile?

Urine is a great fertilizer on the garden and other agricultural lands. Urine provides a good source of many essential plants nutrients that are required for healthy plants growth. However, female urine should be avoided. This is because female urine is very acidic and can affect plants health.

What will make Compost Breakdown Faster?

If you want to speed up the composting process, make sure since, in the beginning, you add the right amount of brown and green organic materials to the compost bin in the right proportion. Moreover, make sure the compost bin is closed by covering it with lid. Ensure that you place the compost bin under a space that has a reasonable amount of sunlight daily.

You can speed up the composting process when you put in place all these important points. And the compost will breakdown more quickly.

Read also: Can You Compost Potatoes?: The Detailed Potatoes Composting Guide

Can dryer lint be Composted?

The short answer to this question is yes, you can compost lint dryer. And the composting task of lint dryer is very easy just like adding shredded newspapers and cardboard.

Can you put Hair in Compost?

Hair is a good compostable material. It can be combined with other garden and kitchen waste such as trimmings, shredded straw, grass clippings, cow manure, dried leaves, shredded tree branches, banana peels, paper towels, and pineapple peels.

Can you put dog poop in Compost?

Despite dog poop is an organic material, the material is usually avoided in compost because dog poop can cause foodborne diseases and can attract pests, and make your compost smell bad.

However, if you so wish, you can add the dog poop to your compost together with dried leaves, weeds, fruits and vegetables, straw, and grass clippings.

Can you Compost Pineapple?

Pineapple and all its other scraps are compostable. The flesh tends to breakdown so quickly when compared with other parts of the pineapple such as the cores, skin, and the crowns.


Onions are very rich many minerals, which can benefit both plants and soil when composted. However, there are some problems with onions when you add them to your compost. Onions can attract pests to your compost and make it smell bad of not properly added to the compost in a correct proportion.

In this article, I looked at how to compost onions properly. I hope you will find the article helpful in understanding the right steps to compost onions. Let me know if you have any question in the comments section below.

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