Worm Composting Grass Clippings

Grass Clippings in Worm Composting Trench

Since it was time to cut the lawn again today, I decided I wouldn’t waste any time getting my grass-clippings-as-worm-food trial started. Jeremy’s question about using grass clippings definitely inspired me to give this grass-only diet a try. Who knows – maybe I can even charge more for the worms raised in my grass fed bed (they certainly charge more for grass fed beef! haha!).

I’m not doing anything fancy at all with this experiment. I have simply designated a short stretch of my vermicomposting trench windrow bed as grass-only. Today, I pulled back the straw from this zone and heaped up some fresh clippings from my mower bag. I then covered them back up with the straw.

Normally, when I use clippings on my beds, I simply layer them on top of the straw, where they add some protective value initially, and food value over time. It will be interesting to see how things differ with the new approach.

Stay tuned!

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  1. Caution with grass clippings. In warm weather, especially if the clippings
    are fresh, the bio action causes a temperature rise that the worms won’t
    like. Left, the grass will ‘burn’ to a sort of grey black ash which really
    isn’t nutritious at all.

    • Kuan
    • June 23, 2010

    I agree with Dave that it will heat up quite a bit if left in a pile like that. My outdoor hot compost pile which comprises of mostly grass clippings (DH is a landscaper) normally heats up to about 153F to 160F. It takes about 2 weeks for it to cool down. If I turn it and add more moisture (& more grass clippings), it will heat back up again.

    Worms will move in once it cools down though.


    • Bentley
    • June 23, 2010

    Nothing like stirring up a bit controversy! Grass clippings seem to be a bit of a…uhhhh…hot topic! haha
    Mark thinks they smell like pee (haha) and are not worth the trouble, while others think they will heat up too much.

    As for me – I LOVE to test thing out!

    That “pile” of mine is pretty small, I can assure you, but I appreciate you guys chiming in since it might not be a bad idea for me to do some temp readings and just generally keep a close eye on this little stretch of bed in general.
    One thing is for sure – I would NEVER recommend anyone do this in an enclosed bin!

    Anyway – should be interesting!

  2. One more thought, perhaps more general on mixing
    vermiculture with composting? I need the high temperature
    that grass gives me to kill the weeds, but I don’t want the
    high temperatures to keep the worms alive!
    I guess this means when mixing the two, you do need to take
    care what you throw on the compost [vermic ] heap.


    • mark
    • June 24, 2010

    Well, I have used a mix of grass clippings and sawdust on top of one of my worm bins and everything is okay. Grass clippings are quite a tricky material to deal with in bulk. I add quite a lot to my compost heap mixed or layered with “brown” materials.

    • Joel LeGrand
    • June 27, 2010

    I have let most of my grass clipping go though a heat before putting them on my veggie raised beds for mulch. But after cutting my orchard
    ( blueberries, raspberries & blackberries), I mulched with clipping of dry straw, leaves & grass/weed matter, with no problems at all. I do not see why a small layer of grass would hurt. I have had the same compost pile as Kuan. I had the same temperatures, but when spread out & not piled up the heat should not build-up. If you mix it with a little soil or brown matter then you should not have a problem.
    Thanks Bentley, we learn by doing!

  3. Joel said “when spread out & not piled up the heat should not build-up. If you mix it with a little soil or brown matter then you should not have a problem.”

    I think that’s the key. But when I’ve just cut the lawn… what
    to do with the clippings ‘meanwhile’? Two heaps?


    • Joel LeGrand
    • July 18, 2010

    on # 7, if one has the time & space, two heaps would do it. You use off the cold heap as the hot one cools, then rotate piles.
    What of inorganic chemicals in compost materials, will it break down or transfer to the humus, then the plants. Not to say anything about the worms.

    • PC
    • August 15, 2011

    Easy composting mower bag trick. 1) After mowing do nothing put mower away for 1-2 weeks or more. Then remove the grass material and add top of worm bin should work fine!

  4. Hi! I’m currently trying to build a habitat for African Night crawlers using similar materials – weed clippings including grass, leaves from trees, etc -so I’d like to know how well this experiment worked for you. Pls post an update soon.

  5. The ‘non’ lazy way (who did that ring a bell with 🙂 is to mix the grass
    cuttings thoroughly with existing compost.
    That way they don’t heat up!
    My latest (lazy) entry, is a near full bag of last years onions.
    Nearly rotten, some still good, all sprouting.
    I couldn’t put them out with the waste now could I !

    regards (another?) lazy gardener / composter / vermicomposter.

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