Can You Compost Weeds?
Yes, with care. Weeds pulled before they flower are a useful green. Seed heads and spreading roots, like bindweed or Bermuda grass, can survive a cold pile, so drown them or hot-compost them first.
At a glance
| Home compost pile | With care |
|---|---|
| Green or brown | Green (nitrogen-rich) |
| Moisture | Wet |
| Prep | Soak or wet first |
| Worm bin | With care |
| Bokashi | With care |
How to compost weeds
Add young weeds pulled before flowering straight to the pile, mixed in like any green. Soak seedy weeds or perennial roots in a lidded bucket of water for about 3–4 weeks until they rot to sludge, then add the sludge. Otherwise, only add them to a hot pile that holds about 131°F (55°C) for several days and gets turned.
Put seedy or invasive weeds in municipal yard-waste collection, where large piles run hot, or drown them first. See hot composting.
What goes wrong
Cold piles rarely get hot enough to kill weed seeds, so spreading that compost plants a fresh crop of weeds. If it happens, use the compost as a top mulch you can hoe, and run the next batch hot. Invasive species like Japanese knotweed should go to municipal disposal, not home compost.
Worm bins and bokashi
Worm bin: Small amounts of chopped, seed-free weeds are fine; worm bins never get hot enough to kill seeds.
Bokashi: Bokashi isn't a reliable way to kill weed seeds or roots, so keep seedy weeds out.
This counts as a green. Adding a lot of it? Check the balance with the compost mix calculator.
From hopcompost.com/can-you-compost/weeds/ · General guidance, not professional advice.
Frequently asked questions
Will weed seeds survive composting?
In a cold pile, many will. A hot pile needs about 131°F (55°C) for several days, with turning so everything passes through the hot core, to kill most seeds.
Can you compost bindweed?
Not directly. Its roots regrow from small pieces. Drown the roots in water for several weeks first, or send them to municipal yard waste.
What weeds should never go in compost?
Invasive species like Japanese knotweed, weeds with ripe seed heads if your pile runs cold, and anything sprayed with a persistent herbicide. Check local rules for listed noxious weeds.