Can You Compost Garlic?

By Veronica Fletcher | 
Last updated on April 3, 2021

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If you’re like me and put triple the amount of garlic in any recipe that calls for it, then you’ll probably have found yourself wondering what to do with all the waste.

Can you compost garlic? No matter how old or fresh the garlic is, you can compost it. You can put every part of garlic in the compost bin, including the cloves, skins, and scalps. Whole cloves should be chopped up before you compost them to prevent any re-sprouting. The one place garlic isn’t welcome is in a worm bin, worms are put off by the strong smell!

Can you compost whole garlic cloves?

We recommend you chop up any whole garlic cloves before adding them to your compost pile. If you put the garlic in whole, then there’s a chance it could re-sprout in your compost. 

This isn’t necessarily a problem because you can easily pull the new sprouts out, but it’s avoidable by chopping or crushing the cloves.

Can you compost garlic skins?

Garlic skins can be added to a compost pile and will break down over time, but there’s actually a lot of other uses for garlic skins that you might want to consider. You can use them in cooking and even in skincare.

Garlic skins are packed with vitamins and antioxidants that get transferred into the food when you cook with them. You can boil them in water to make soups and stocks, and then after straining them throw them in the compost. Or you can grind the skins up to make a powder and use it in pesto or bread to give a mild garlicky flavor.

Can you compost garlic leaves (the stalks)?

Garlic scapes are the leaves of a garlic plant and are sometimes known as garlic stalks. 

garlic scapes
Garlic scapes, sometimes called the leaves or stalks (source: A. Drauglis)

Garlic leaves are fine to add to compost. They’re a good source of nitrogen and will break down well, especially if you chop them up before adding them. The only thing to be wary of is composting diseased garlic plants. If your pile doesn’t get hot enough the spores can survive and go on to contaminate other plants. 

If you put diseased garlic leaves in your pile, it needs to reach at least 150 degrees Fahrenheit to kill all the harmful pathogens. This is definitely possible but requires that you give your compost pile a lot of care and attention. The greens:browns ratio and moisture levels need to be just right for the compost to heat up.

You can also use the leaves in cooking. They make a great vegetable side dish, or you can eat them raw in salads just like spring onions.

Can you compost cooked garlic?

Yes, you can compost cooked garlic with one caveat. If the garlic’s been cooked in oil or butter, then you need to be careful with how much you add. If the garlic hasn’t been cooked in fats, then there’s no issue with composting it.

garlic basted in oil
Garlic is often cooked in oil (source: smallest forest)

Oil isn’t the best addition to a compost pile because it’s very slow to breakdown and can create barriers in your compost which air and oxygen can’t penetrate. Dairy foods like butter are prone to attracting unwanted guests to your pile.

If you have a large, healthy compost pile, then a small amount of oil and butter won’t cause any problems. Smaller piles have less margin for error, but as long as the fats only make up a small percentage of the waste you’re putting in, it should still be fine. Adding some brown materials at the same time as the cooked garlic will help stop any pests from discovering it.

Can you add garlic to a worm bin?

Garlic is one of the few things that we don’t recommend putting in a worm bin, especially if you have a small or new system. It’s not that it won’t get broken down, it will, it’s just that the worms don’t like it.

Worms are sensitive creatures, and strong or odorous foods can overwhelm them. Any garlic you put in your bin will be left well alone by the majority of worms until it has completely rotted down. As garlic decomposes, it releases sulfur gas leading to a putrid smell coming out of the bin that can hang around for months. Other gases are also given off, which in large volumes can irritate the worms.

In their natural habitat, the worms can easily avoid things that irritate them, but in a small confined bin, this becomes harder. By adding garlic, you’re creating an unpleasant environment for the worms, and this will slow down your overall system.

Garlic skins take forever to break down, so if you put them in your worm farm you’ll likely still be finding them long after everything else has disappeared.

If you have a lot of garlic and you want to put it in your worm bin, then a good workaround is to use Bokashi. Bokashi is a Japanese method that ferments the food in an anaerobic environment to break everything down quickly and without smells.

bokashi mix in a white bucket
Bokashi pre-compost (source: Mack Male)

The resultant mixture, known as bokashi pre compost, isn’t quite compost, but you can feed it to your worms in moderation. The pre compost is acidic, so you need to add it slowly and also add something alkaline like eggshells to counteract the acidity. But once your worms get used to the new food, they should love it.

If you’re interested in learning more about Bokashi, we have a section explaining how to do it in our article on composting indoors without worms. Or you can check out our article reviewing the best bokashi bins.

Can you compost wild garlic

Wild garlic is a cousin of the garlic we use in the kitchen, but it grows much more readily, so it can quickly become a nuisance in your yard. 

Wild garlic
Wild garlic plants grow very quickly (source: velodenz)

You can compost the leaves of wild garlic as long as they haven’t seeded yet, but we wouldn’t recommend putting wild garlic bulbs in a home composting pile. The bulbs can persist for a long time in compost, and you might find that the weed re-sprouts when you use the compost. 

If you’re hot composting, this should theoretically kill the bulbs, but in reality, most home piles don’t get hot enough.

An alternative is to kill the bulbs before you compost them. There are a few ways to do this, including drowning the bulbs or nuking them with the sun. Once you’re sure the bulbs are dead, you can go ahead and throw them in your compost pile.

Can you compost garlic mustard?

Garlic mustard is a very invasive weed that we don’t recommend composting. Most home compost piles don’t reach the temperatures required to kill garlic mustard seeds. If the seeds survive in your compost, then you risk the plant sprouting up wherever you use the compost. 

Garlic mustard
Garlic mustard is an extremely invasive plant (source: Wendell Smith)

To kill garlic mustard seeds in compost, the pile needs to reach 150 degrees Fahrenheit which, although not impossible, is quite tricky. The seeds are viable for 5-7 years, so using time to kill the seeds is not feasible either. 

To get rid of garlic mustard, you need to pull the plant out by its roots. Then as with wild garlic, you can either drown the roots or nuke them in the sun. We would deal with them like we deal with other invasive weeds and bag them up in black plastic bags, then leave them in the sun for a few months. This will generate sufficient heat to kill the seeds, and once they’re dead you can add the plant matter to your compost safely.

About Veronica Fletcher

Veronica has a passion for all things eco-friendly. After growing up on a farm in Ireland, she went on to study Chemistry and Environmental Sciences. Veronica has also volunteered in many sustainability roles, including conservation efforts in Bangladesh and teaching Environmental Sciences to schoolchildren in Kenya.