Cat Litter Vermicomposting

Eco-friendly Cat Litter

One topic I’ve been asked about quite a lot is pet waste vermicomposting. Of course, it is totally understandable – after all, there are millions of pet owners in North America, and dealing with pet waste materials is definitely one of the not-so-enjoyable responsibilities associated with taking care of our furry friends.

For quite some time I’ve been meaning to make a video (and write) about an design idea I’ve had for a pet waste vermicomposting system. As I’ve mentioned at least a few times here on the blog, it’s definitely NOT a good idea to add pet (or human) wastes to our regular composting systems. There are some exceptions to this rule – the poop from vegetarian animals like rabbits, guinea pigs etc should be totally fine, although you should still be careful using it based on the high nitrogen content.

Originally I was planning to set up my own pet waste system in the backyard (making sure to take lots of pictures) and then collect cat poop from our two litter boxes and add it to the system (likely testing out my biodegradable poop bags while I was at it). Notice I didn’t say that I was planning to add my cat litter to the system. If you are using clumping (or regular) cat litter, as we have been doing for years, you definitely DO NOT want to add this stuff to a composting system. Back when I was young and dumb I did this and ended up with the most disgusting clay-poop cake you can imagine. Not exactly worm- (or environmentally-) friendly!!

During a recent visit to our local supermarket, I noticed they were offering a new ‘green’ cat litter (‘Presidents Choice’ brand – likely a familiar name only to my fellow Canadians). It’s not the cheapest stuff, that’s for sure, but it claims to be twice as absorbent as clumping cat litter – and more importantly it is ‘compostable’!

I picked up a couple bags of the stuff today, and I am really looking forward to testing it out (likely in one litter box to start). Aside from feeling good about no longer sending hundreds of pounds (or more) of clumping cat litter to the dump every year (not to mention the hassle associated with cleaning and throwing it out in the first place), the green cat litter is really going to help me test out my pet waste composting system.

I’ll certainly write a lot more about this once my system is up and running, but I figured it was worth mentioning now so all you pet-fanatic-vermicomposters out there have something to look forward to.

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    • Kim from Milwaukee
    • November 7, 2008

    Bentley, you’re my HERO (besides Barack Obama, that is) !!! Can’t wait to hear about your results!

    • Rich A.
    • November 7, 2008

    Tumbleweed makes a “Pet Poo Converter” — see

    • Christine
    • November 8, 2008

    We have dwarf hamsters. I don’t worry so much about their poo as I do the hard wood shavings. I bet they take forever to break down, but I bet the worms would love it.

    • Eve
    • November 8, 2008

    What do the ‘pellets’ look like?
    Just wondering if they are plant based. If so could make a nice amendment for the worm farm when scraps are low.

  1. I will be realy interested in how you get on with the cat litter and your composting system for pet waste.
    I reckon worms can process anything that was once alive and aslong as we take health precautions we can give the worms anything.

    • Bentley
    • November 9, 2008

    Thanks for chiming in, everyone. I’m definitely excited to try this litter out. It is apparently ground up corn cobs, and it looks a lot like regular litter.

    • Jessica
    • November 19, 2008

    I think compostable cat litter is a GREAT idea! However, a little vet advice… Cats “learn” what litter is during the first few months of life…so if you got your kitten at 8 weeks old and it has always had fine granular cat litter, it may not recognize wood pellet litter or shredded paper as litter. Obviously some cats are more finicky than others, so maybe your cat won’t mind! If you want to try to change the litter, offer a separate litter box with the new litter before getting rid of the old litter completely (to prevent your cat urinating on your bed or sofa or laundry!) or alternatively try gradually mixing the new litter with the old.

    • Bentley
    • November 19, 2008

    Hi Jessica,
    Thanks for stopping by and sharing your expert advice. I’m really impressed with how much this particular type of compostable litter looks like the real deal. The cats don’t seem to mind it too much – although I’m only using it in one of the two boxes at the moment (glad to see that’s a recommended approach).

    I was thinking of trying to mix in other biodegradable materials (shredded cardboard, peat moss etc) in an effort to save some money, but I’ll definitely do it slowly, as not to offend my feline friends.

    • Stephanie
    • March 28, 2009

    We currently use equine pine bedding for our cats’ litter box. Spaz Boy and Mimi made the transition to this litter very quickly, and it eliminated litter found outside the catbox. I have been bothered that it is so biodegradeable yet just gets bagged and put in the trash. I think I will also pursue the notion of vermiculture to help us with this.

    While I understand that this compost wouldn’t be good on vegetables and such, what about blueberry bushes or grapevines?

    • Bentley
    • March 30, 2009

    Spaz Boy?

    To answer your question, Stephanie – where you use the compost is totally up to you – it just a matter of your risk tolerance. I would probably feel comfortable using it for bushes and vines.

    • Stephanie
    • March 30, 2009

    Yes, Spaz Boy. He definitely lives up to it. Mimi is actually Screaming Mimi, and she lives up to that as well.

    Thanks for the comments on using this compost on the sturdy bushes and vines. It makes sense not to use it on something that is that close – production wise and proximity wise. But the bushes and vines seemed like they were safer. The apple trees might benefit as well.

    Thanks for the info.

    • Janet
    • October 31, 2009

    We have two cats and use Good Mews which is recycled newspaper that is in pellet form.

    We just started worm composting this August so are newbies, but I am thinking of starting a seperate worm system just for the cat litter and possibly guinea pig litter and use that compost tea for just the lawn and roses. Not for the garden.

    • Bentley
    • November 1, 2009

    Good idea, Janet – just make sure to set up the worm habitat (the bigger the better) prior to starting to add the cat litter waste, since it is pretty potent stuff on its own.

  2. Glad you clarified about the regular compost being a bad idea – I can’t believe the number of people that think it’s ok to do this!

    • Emily
    • November 17, 2020

    Can you do an update on this? How did the compostable litter work out?

    • Bentley
    • November 20, 2020

    Hi Emily,
    That was some time ago now, but here are some follow-up posts that might help:

    More recently I tested out “chick starter” feed and found it to work quite well as a clumping litter – even less expensive than cheap clumping clay litter. You do need to be careful if you plan to compost it, though, since the feed has a lot more nitrogen than the corn cob based litter so even more potential for ammonia release and just generally hazardous conditions for the worms.

    • Emily
    • November 20, 2020

    Thank you for the response!

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