Can You Compost Weeds?


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Weeds are everywhere! What if you could compost weeds instead of throwing them away? Can you compost weeds?

Yes, you can compost weeds and it’s a great idea instead of throwing them out. But there are some things to be aware of, so you don’t ruin your compost pile

This article will cover composting weeds, how to compost weeds, and how to avoid problems with weeds.  

Can You Compost Weeds?

If you are a gardener, then you will undoubtedly have to deal with weeds. No matter how vigilant you are, these hardy little seedlings will always pop up where they are not wanted.

If you are new to composting, you may ask yourself, can I put weeds into compost without causing any problem?

The answer is simple – yes. Weeds are one of the most common and easiest things to compost. If your yard is plagued with weeds, you can use them to create wonderful plant feed for the plants you want to grow by composting all those pesky weeds.

Weeds are defined as wild plants growing where they are not wanted and competing for nutrients with plants you are growing and cultivating. Basically, you decide if it is a weed or not! If you like dandelions or have a fondness for nettle tea, then these common weeds can become just another plant in your garden!

Weeds can be a great addition to your compost, as many have deep roots that can access the nutrients that are deep underground. These nutrients are then brought to the surface when you add your compost to your soil. 

The most common area to want to keep weed-free is your vegetable patch, as the weeds will take nutrients from the soil that you want to be left for your vegetables.

If you have a serious problem with weeds and have had enough of weeding, I recommend you try the no-dig method.

The no-dig process is perfect for vegetable plots. This method uses mulch to suppress and deter weeds, and leaves the soil largely undisturbed to build up beneficial microorganisms in the ground. 

To start using this method, cut down all the weeds in the area you want to use, but don’t dig them up. You can add the cuttings to your compost. Then lay a light suppressing material over the area, like black plastic. Cardboard is perfect for this as it will bio-degrade into the soil.

Next, lay compost mulch over the cardboard and compact it down. This method will successfully suppress weeds and discourage them from propagating to other areas of your garden bed.

The process can be repeated at the end of each growing season to prepare the area for planting in spring.

How to Compost Weeds

Weeds can be tossed straight into your compost without the need to cut them up first. It is best to pick weeds when they are young, eliminating the need to shred or chop them in pieces before adding them to your composter. 

Adding young weeds is preferable because they will be small and delicate enough to break down very quickly. There are other reasons why adding young weeds to your composter is best, and I have detailed them in the section below to avoid problems.

Weeds can be added with any soil that might cling to the roots, as this will just get mixed into the compost, so there is no need to remove it. In fact, because weeds will be composted with bits of soil, it is possible to make compost with weeds alone!

How to Avoid Problems With Weeds?

Problems can still occur when adding weeds to your compost. The main issue that you will want to avoid is having seeds or hardy roots of weeds in your compost. This is because weed seeds will contaminate your compost and spread weed problems when you use your compost.

The other issue is with plants that have a sturdy root, like bindweed, as these roots will survive and continue to grow in your compost.

You can avoid these issues by only composting young and annual weeds. Pick weeds before they have flowered to eliminate the possibility of them containing seeds.

Some composters, like hotbins, will reach high enough temperatures to kill any weed seeds in the plants, but open-air composters will probably not reach high enough temperatures. Of course, open-air composters will always have some issues with contaminates, but if you ensure you pick out any weeds as soon as you see them, you will be able to control weeds more effectively.

Hot composting will be needed to break down hardy perennial weeds and seed heads. A cool compost pile is good enough for grass clippings and other organic material, but troublesome weeds will need more heat. You can try garbage bag composting in direct sunlight if your local area doesn’t get too hot. 

If you have a weed with an extensive rootstock, then you can leave it in the sun to wither before adding it to your compost. This exposure will effectively kill the root, so it will not survive in your compost.

A well-maintained hot compost pile will also help prevent harmful pathogens and bacteria from spreading in your compost pile.

Composting Weeds Final Thoughts

Remember that your compost is an ideal environment for garden plants, being warm and full of nutrients. By regularly turning your compost, you will also ensure that any cheeky weeds trying to grow in it will be kept at bay.

Check out these other composting articles to learn more about what’s compostable: 

Composting Weeds FAQs

Can weeds go in a compost bin?

Yes, weeds can go into a compost bin. Composting weeds will benefit your garden and plants. Weeds compete with other plants for space and nutrients. They also take up valuable resources needed by other plants. Weeds tend to decompose faster than other organic matter, so they’ll end up being digested by the microbes in the compost before any other material. 

Why should you not compost weeds?

The biggest reason you should not compost weeds is if you’re unable to maintain a hot compost pile. Without keeping a hot enough temperature, the weeds you’re trying to compost will not decompose, and the weed seeds will survive. That would end up with weeds spreading, instead of being composted.

What do you do with pulled weeds?

Pulled weeds can be used as mulch around new plants. Pulled weeds can also be added to your compost bin. Just make sure that you remove any roots from the weed before adding it to the compost. Also be sure to keep a hot compost pile to kill off the weed seeds.

Do grass clippings cause weeds?

Grass clippings don’t cause weeds, but they are one of the most common sources of weed seeds spreading across your lawn. Grass clippings contain seeds that germinate easily when moistened. If you add grass clippings directly to your compost bin, or put them on top of soil, they could start growing again after you’ve finished using them. Be sure to maintain a hot compost pile, so the wee seeds are do not survive.

Will dead weeds decompose?

Dead weeds will decompose over time, but they won’t decompose any faster than other organic matter. However, they will take up space in your garden and make it harder for new plants to grow. To speed up their decomposition, you can bury them under mulch or cover them with straw.

How to compost weeds fast?

Compost weeds faster by maintaining a hot compost pile. Turn the pile every few days to expose all the weeds to air and light. The hotter the pile, the quicker the weeds will decompose.

What weeds should not be composted?

Do not compost weeds like bermuda grass, quackgrass, morning glory, buttercups, and crabgrass if you have a cool compost pile. Only hot compost piles will be able to kill the weed seeds, so weeds don’t grow in and around your compost pile.  

Can you compost weeds killed with Roundup?

It’s best not to compost weeds killed with Roundup. Glyphosate kills weeds well by inhibiting their ability to make proteins. However, glyphosate is toxic to humans and animals. Therefore, it must be used carefully when applying it to lawns, gardens, and crops that you plan to eat. 

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Written by:

Denise Davis
I am an avid gardener who has spent most of her life in the garden, growing and cultivating organic veggies for friends and family. I love the earthy smell of composting and making homemade fertilizers from natural ingredients like old coffee grounds or eggshells. Gardening is a great way to get outside, learn new things about nature, exercise your body (and brain!) and eat healthy food you have grown yourself!