Choosing planting

Can you compost weeds?

And if so, how do you do it?

Contents

Modified the 30 November 2025 by Olivier 2 min. Difficulty: Beginner

A “weed” does not exist. Let’s say some gardeners do not like certain plants in certain places (that’s for sure!). We would rather call them adventive plants in that case. These adventive plants include wild plants, which have their use in the garden (biodiversity, food and shelter for wildlife, bio-indicators…), and cultivated or uncultivated plants that have no business being where they grow in the vegetable patch or elsewhere (invasive, smothering or simply unsightly). How can we make it so once uprooted without ceremony and other forms of rough handling, these adventive plants or “weeds” still contribute a little to garden balance? Compost them, of course! Indeed, all this green waste is saturated with water, nutrients and minerals. It would be a shame to waste it, so let’s recycle it.

→ Let’s see how to compost adventive plants and the mistakes to avoid!

composting weeds, weed compost, composting adventive plants

Some adventive plants can be composted rather than thrown away

Difficulty

What could be the problem with composting "weeds"?

If you incorporate weeds that have set seed and the compost heap doesn’t heat up enough, chances are you will spread those seeds when you use your compost. Seeds can even germinate directly in the compost.

Worse still, some plant parts can regrow directly in the compost: bindweed roots for example, or potato peelings, kitchen waste that can sometimes turn an ordinary compost heap into a mound of potatoes (that said, it can be handy…).

In other words, you can’t just throw everything on the compost without thinking. Especially if it isn’t well aerated, moist or doesn’t have a good carbon-to-nitrogen ratio. These factors help the compost heat up properly, thereby killing contaminants and seeds of adventives.

→ Find all of Ingrid’s tips for successful composting: all Ingrid’s tips to succeed with compost.

composting weeds, weed compost, adventive compost

Beware of seed dispersal in your compost !

How to avoid these problems?

Fresh weeds, like all plants, are full of water and are therefore perfect for speeding up warming of the compost bin. Just avoid three types of weeds in case the compost does not reach the temperature needed to prevent problems. Consequently:

Avoid, if possible, plants that have gone to seed, although you can cut off flowering stalks;
Avoid plants whose roots, stems or other parts can quickly take root and thus invade the composter: nettle roots, bindweed, potato, periwinkle, bedstraw…;
Avoid diseased plants.

Dry weeds should not be forgotten. Especially for plants that can root in a compost heap. If you dry them for a few days in the sun, the risk becomes non-existent: do this with plants with long running roots such as bindweed, for example.

If your compost heap reaches 50°C at its centre, you can place the three types of adventive plants to avoid (plants that have gone to seed, invasive species and diseased material) directly in the middle of the heap.