Worm Composting in a Compost Tumbler

Over the years, I’ve stayed pretty consistent with my views on the “proper” use of compost tumblers – and what that has amounted to is a firm recommendation NOT to use them as an actual worm bin. Instead, I have suggested that people use them to make “worm food”.

Maybe I’m softening in my old age, I dunno…but at any rate, I have decided to turn my own tumbler into a worm bed this year and see how it pans out! Now, right off the bat let me point out some important details. For starters, I am located in northern temperate North America (in Southern Ontario). Our summers tend not to be really extreme in comparison to many other (more southerly) locations. Multiple days above 30 C (86 F) would be considered a “heat wave” – and it’s rare to get above 34 (~ 93 F). Also, my tumbler is located underneath a tree, so that will make a big difference in terms of preventing overheating.

If you happen to live in a zone where 95 F (and beyond) is just “par for the course” as a daily high during warmer months, it will definitely be a lot more difficult to keep worms alive in a tumbler (or any plastic bin sitting outside for that matter) – even if it is in the shade.

Setting up the bin didn’t involve much in the way of planning or strategy. There was already a fair amount of partially decomposed cardboard in there. I added some shredded pizza boxes, some old coffee grounds sludge (that had been sitting in a bucket outside), and transferred wormy material from my “pet waste vermicomposting” heap (very well processed material with lots of worms in it – hasn’t been added to for more than 6 months). I also added some water to moisten the cardboard (all of which was quite dry).

Moving forward, I’m sure I will “tweak” things in an effort to optimize the system a bit – but all in all, I’ll be keeping the project nice and simple (we know what happens when I try to over-complicate things! lol).

Stay tuned.
Should be fun to see what happens!

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    • Pete
    • May 9, 2014

    I have a similar composting bin on a much smaller scale that I purchased via Amazon. I use it as part of my 3 step process. My first compost bin is an open holding bin for leaves and other similar materials that I eventualy blend into my composter with food scraps. I then after about 30 days use as mulch and for worm food. I plan on turning it into a worm bin this winter. Since I live in Louisiana it would be too hot for the worms in the summer but I’m thinking it might work well in the cooler months. Especially for my African Night Crawlers. I like your design. It looks like you won’t have too hard of a time turning over the compost.

    • Nicole
    • May 13, 2014

    Hi Bentley
    I live in Northern British Columbia and have started composting with Red Wigglers.
    Will Red Wigglers live up here through our 30 below Celcius winters? Or should I keep them only in the house?
    If I put them in compost bins outside throughout the summer will they survive or should I try to collect as many as possible come fall?

  1. used tumbler for three years now in Oakland CA, (northern ca).

    Yeah the problem is overheating. otherwise fine.

    Have never figured out how to reduce the moisture but worms never minded. Is that the anerobic muck? Why is that bad? Smells ok.

    Had an unusual heatwave in the 90’s and I screwed up and did not move the bin under trees and shield with large umbrella. First my young granddaughter asked today when she got off the plane was “how are the worms?” Will have to explain they took a vacation 🙁

    • Bentley
    • May 16, 2014

    Pete – thanks for sharing your thoughts! Yeah, I would imagine that trying this in Louisiana would be challenging during the warmer months!

    Nicole – with some very serious preparation of outdoor (in-ground) systems you might at least be able to keep them alive over the winter. Guess it would depend on how far down the solid-freezing zone goes. Either way I definitely recommend keeping one or two “insurance bins” going indoors. They really don’t take much effort at all – could feed them mainly bedding.

    Len – if it doesn’t smell bad, it’s unlikely that it’s “anaerobic muck”. The anaerobic stuff isn’t always necessarily going to be “bad”, but it’s best avoided as much as possible since it can result in harmful compounds such as alcohols and various acids etc.

    • John Ski
    • May 30, 2014

    I was thinking if your worm tumbler (lol) idea doesn’t work out you may have the ultimate worm food optimizer here. It could save you time mixing and pre-decomposing your worm food mix.

    • Friend
    • January 30, 2015

    My community garden in MD is thinking about doing this and they do not have the money leverage to spend on something that won’t work properly so needless to say I am very interested in how your plays out.
    Please, let me know how the worms fare. Will they freeze up during the winter or be baked by the summer sun and overheat? How do you control the moisture levels and account for the liquid produced from the vermiculture? Will they get injured by the tumbling process?

    I am enthusiatically looking forward to hearing back from you.

    Sincerely, Your fellow gardening friend.

  2. Winter, even though mild, temps drop to high 30’s at night sometimes, hasn’t been anywhere as successful as summer in the shade was. I use a 50? watt waterproof heating pad. Gets way to wet inside especially since I’m covering up the tumbler to keep it warmer. I’m using European night crawlers.

    Also, I’ll need to add at least a second tumbler or pile as a transfer station while waiting for everything in the first tumbler to get eaten/decomposed.

    • Friend
    • February 7, 2015

    Hi Bentley,

    How would this work in Maryland? Is there any special care required summer verses winter care? I am in zone 7a on the map = 10°-5°F in winter and about
    80-90°F summer. Any tips?
    Thank-you, Mrs. Friend

  3. I’m using European night crawlers not red worms because I also needed some deep burrowing worms for my garden.

    “ability with tolerate a broad range of temperature extremes compared to other worms. Typically Euros do best in temperatures between 60 F and 70 F (15 C – 21 c) and can withstand temperatures from about 45 F to 80 F (7 c – 26). When it gets below 45 F ENCs need to be protected from the cold. It’s a bit riskier to keep ENCs in outdoors in the winter as they are more cold sensitive than red worms. If you can maintain the Euros beds above 45 F give it a try. However if you can move them indoors or to the basement start there.

    Euros also need protection from the heat. They will naturally borrow deeper into their beds when they get warm, or worse will try to escape the bin. Keep the beds under 80 F through the use of shade, careful watering, or experimenting with putting jugs of ice cold water buried in the bedding. If your worm farm is small consider moving them into the basement”

    • Debbie
    • March 6, 2021

    Hi Bentley,

    I’ve got a question and this might be the most relevant post to ask? (Maybe).

    I read that worms need some airflow, oxygen, aeration, etc. I’ve got the 7 gallon black plastic tubs / yellow lids. I perhaps didn’t drill enough holes. The bin is moist and pretty happy. Whenever I put in leftover Napa Cabbage leaves, the mites get reeeally happy too. I tried to be chill about it, but as you point out, too many mites might mean sub-optimal worm conditions. So one thing I’ve been doing is taking my small bin outside when the sun is out, and opening the lid for full air.

    Here’s the thing. I loooove getting my hands in there, and digging around, and seeing what’s up with the wormies. It’s interesting how warm it is in the middle of the bin. But I also know that you’ve said not to disturb the worms too much and they’d be happier and more productively munching on food if left alone.

    I know that it’s okay to occasionally go through and toss the bin a little bit for air. And might be good for lessening the mite population. Where does the line cross from “annoying” the worms to “disturbing / stressing” the worms? I’d say my usual may be twice, one week. And then get bored for 3 weeks and leave them alone. Then back and feed them and check them several times over the next couple of weeks.

    • Bentley
    • March 18, 2021

    Hi Debbie – that’s totally normal!! I likely bother a lot of my worms more than that – haha – but I also tend to have a similar feast and famine cycle. These worms are pretty mellow characters (Red Worms in particular)

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