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I usually discard weeds but it occurred to me that they would probably be good for compost.

Are there any steps I can take to use them in compost without having them grow again when I use the compost? Do different types of weeds need different treatment prior to composting?

The main weeds I have are dandelions and "farmers friend".

bstpierre
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WileCau
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4 Answers4

71

If the weeds have gone to seed, any seeds in the compost mix will likely germinate when you come to use the compost. These, you have to dispose of differently.

Otherwise:

  1. Put the pulled weeds into a light-blocking sack for a week to make sure they don't have any energy to grow in the compost.
  2. Cut them up into small pieces to break their roots and leaves and encourage faster composting. A chipper is great for this if you have one, but I just use secateurs.
  3. Put the shredded weeds into a covered composter. You can bury them if the compost material if you don't have a cover.

After this kind of treatment, even the hardiest of dandelions should give up and compost properly. Provided you break up the roots, they shouldn't give you any problems.

Paul Turner
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Generally, they just need to be buried in the compost heap. If the heap gets hot enough, it will kill off pretty much every seed imaginable (except for tomatoes - I remember visiting sewage treatment plants and tomatoes still managed to germinate even after everything else was processed/sterilized).

Tangurena
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Since some perennial weeds can regenerate from even tiny root fragments, they are not considered safe for composting unless you use the Berkeley method of hot composting, and measure the temperature to ensure that your compost temperature is within bounds as prescribed by that method.

Another way to treat perennial weeds is to dry them out to kill the roots and stems as some can regenerate from stem cuttings (eg. Tradescantia). I put them on a plastic tarpaulin and leave them in full sun until I'm sure that they are desiccated and dead.

If the weed has flowers eg. Scottish thistle, I remove the flowers and place in a bath of water and drown them for a month or so.

Dried weeds can then be used as a mulch to compost in-situ, or, added to the compost pile.

Graham Chiu
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6

My suggestion would be to check it the weed is flowering. If it has any flowers remove them before throwing it in your compost bin. If done right, your compost bin will reach high enough temperatures to kill the seeds and plant but I generally remove the flowers before putting it in the compost bin

JStorage
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