Here is a question from Jeremy:
I am planning on starting my own worm bin. The main reason I
would want to start one is that I mow my lawn every week and I have
nothing to do with all of my grass clippings. I have an average sized
lawn, about 5k square feet, and I mow once a week during the summer
months. I have thought about a standard tumbler composter for the
grass, but the idea of a worm bin really intrigues me. My main
question is this, can the worms survive, and hopefully thrive, on a
diet that consists mainly of grass clippings? Of course I will throw
in whatever food scraps I can and probably shredded junk mail. I was
just wondering if they can handle that bulk of grass weekly. Thanks.
This is a great question – I’m sure many other have wondered the same thing (or something similar anyway).
The short answer is probably “yes” – composting worms could likely be sustained on a diet of primarily grass clippings. There is however a very significant “BUT…” as well!
Here are some things I definitely would NOT recommend doing:
1) Using large quantities of grass clippings in an enclosed plastic (eg Rubbermaid) type of “worm bin”. Accumulations of grass clippings left to sit tend to turn into a wet slimy mess in some spots, and a dry moldy mess in others – neither of which are great for worms. Add to that the fact that this material has a pretty low C:N ratio and tends to off-gas ammonia when left to sit, and you can probably see why you wouldn’t want a lot of it simply sitting in a normal worm bin. Sprinkling in small amounts periodically won’t likely cause issues though.
2) Filling a typically backyard composter with grass clippings, then buying a pound of worms and adding them to it (assuming they will magically turn the material into beautiful rich worm compost). Based on what I mentioned in #1, it should be pretty obvious why this is not the greatest of strategies. Grass clippings alone are absolutely NOT an ideal Red Worm habitat.
Now that I’ve rained on everyone’s parade (haha), let’s chat a bit about how they CAN be used as worm food!
In all honesty, I think you were definitely onto something with your idea involving tumbling the clippings. A compost tumbler is a fantastic tool for getting materials ready for worm composting. If you mixed up a batch of grass clippings and shredded cardboard (moistened), fall leaves, or straw etc and let everything compost for a bit in the tumbler (turning periodically of course), after a week or two I bet you would be left with a really nice “worm food”.
Grass clippings CAN be use as-is, but the secret there is having a large, well-established (and high quality) worm habitat in place already. For example, I add grass clippings over top of my trench beds all the time, and they provide a great cover material and food over time. I have also added plenty of clippings to well established backyard bins containing lots of worms. In both cases, these are systems with excellent ventilation, and also systems with enough quality habitat down below that the worms can simply let the clippings rot, and come up to feed from below at their leisure.
Once you have a good (sizable) worm habitat in place, and you start layering the clippings over top, I am quite confident that you could continue to do so (and stop feeding them anything else), gradually creating a grass-only worm composting system – along with an associated population of composting worms well-adapted for this environment.
Now you’ve got me wanting to try this!! Perhaps I will add only clippings to one stretch of trench for the rest of the season and see what happens!
Anyway – I hope this helps, Jeremy!