De-weeding the Compost Pile

by Sandy Swegel

Playing in the dirt is, of course, the most fun reason to garden. This week I’ve been playing in the compost which is doubly fun because I get to play with the earthworms too.

What to do with Compost Weeds

My compost style is very passive. I keep three big bins going. Starting the bin is easy. I make sure there’s a couple of inches of finished compost at the bottom to inoculate the pile. Every week I clean up something in the garden and throw it on top of the compost. I generally don’t put in sticks unless I feel like cutting them up into smaller pieces. The most important addition to the pile is vegetable scraps and greens like grass clippings. I put those in the middle and tuck them down under the dried up spent foliage. The vegetable and green scraps invite earthworms in so my pile is breaking down in the traditional way that browns and greens break down and earthworms are doing their thing at the same time. Sometimes if there’s too much organic matter, I throw in a shovel or two of soil. I water the pile if we haven’t had rain. In Fall I throw some leaves on but also have separate bins for straight leaf mulch.


This is Cold (or Warm) Composting. This is not the fancy layering and turning that extension services advise composters do to kill all the seeds and disease. The pile gets hot in the middle, but without the regular turning and fine-tuning of ratios of browns and greens, my weed seeds don’t all get killed. I don’t put diseased foliage into the pile. But with a minimum of work, I get a lot of compost.

So what do I do about the weed seeds?
Basically, I get them to germinate then cut their heads off. De-weeding the compost pile.

Sometime in August or September, I scrape off the completely uncomposted material and put them into another bin. Then I vigorously turn my pile and mix it together. It’s about 80% finished. I leave it alone except to water it if needed. Each week all the weed seeds germinate into little green plants and I shovel up that top two inches of little weeds, breaking their necks and put them back into the compost pile. The next week, more seeds have germinated and I break them up too. Usually, after about three weeks, the weed seeds have mostly all grown out and the compost is ready to get spread on the garden after the soil freezes.

Easy and not much work.

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