Cold Weather Vermicomposting Questions Answered

I (understandably) received quite a few “burning questions” relating to the topic of cold weather vermicomposting for our recent “Win Worms Monthly” contest. Given the time of year (i.e. how relevant this topic is), I thought it might be fun to turn this into my very first (unofficial) podcast.

So I quickly put together a little background info, organized the questions, and started recording!

The recording is about 45 minutes (I have no idea why it says “7:48” – but it is definitely a lot longer than that). If you would like a downloadable version (so you can listen on a portable player, smartphone etc) just let me know and I’ll make that available (NOW AVAILABLE!!). Just so you know, the file is about 30 MB.

Some of the topics touched on:
– Keeping worms ALIVE versus keeping an ACTIVE vermicomposting system.
– How to protect a larger backyard bin (eg. typical backyard composter) from the cold.
– Temperature tolerance of different species of composting worms.
– Shipping worms during cold weather
– Keeping smaller systems warm (or at least preventing them from freezing)

…and much more!

I almost forgot…

Be sure to also check out the Winter Worm Composting section on the HOT TOPICS page.

Here are a couple of the specific posts I mentioned in the podcast:
Heating a Small Worm Bin in the Winter
More on Small Winter Worm Bins

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  1. I would like an downloadable link for a MP3 file. If you’re going to do a bunch of these an RSS feed for podcatcher software might be an idea too.

    • Bentley
    • October 24, 2012

    No problem Mike – will put the download link in the post ASAP.
    Part of the reason I’m calling this (and perhaps the next few) an “unofficial” podcast is because I haven’t gone through the process of creating a proper system (with feed etc) for all this. Will be spending a lot more time on this aspect fairly soon – but in the meantime I’ll simply record them and make them available here on the blog.

    Thanks for your input!

    • Bentley
    • October 24, 2012

    Recording is now available for download.

  2. Thanks

    • Barbara Osterberg
    • October 24, 2012

    Hi, I listened to your podcast and enjoyed it a lot. Very informative. I’m very new to worms and worm bins. I do have a 3 tier bin and so far am doing ok. I’d like to hear about vermicomposting in Oxnard, California. We may not get too cold here, but it does get very windy, especially on my decking which is a wind tunnel. My worm bin is right there. Do I need to worry about winds in So.California? The area is protected on 3 sides. Just how cold and windy will the worms tolerate? Thank you so much for the information. I just love my little guys.

    • Sharon K
    • October 24, 2012

    Great job on the podcast! Lots of really good info. Looking forward to keeping most of my worms outside but have already brought the African night crawlers inside. Have already gotten into the 40s (Fahrenheit) this year so they are toasty warm in our living room. My spouse wasn’t too thrilled when we first started worming but he has really gotten involved with every aspect and we enjoy feeding, harvesting and making new kinds of bins together. I would have to say the worms have brought us closer LOL! Thanks for all you do.

    • tams
    • October 25, 2012

    hey! that was great. I really got a lot of good ideas from all your great answers. The sad truth is, winter cold snap has hit and I was unprepared. Is it true the worms may still be alive even though the compost has frozen solid? I will be working on this.

    • Bentley
    • October 25, 2012

    Hey guys – thanks for the positive feedback! It means a lot!

    Barbara – If we are talking about cold winds then I’d definitely recommend creating some sort of wind block if at all possible. Tarps work great for larger systems – but aren’t really ideal for locations (or times of year) that get warm weather regularly (it can cause your system to overheat and really impede air flow – better for when it’s quite chilly).

    If you could simply put up something solid that won’t get blown over (maybe a little shelter wall made from those large concrete construction blocks) it would make a difference.
    Sharon – really glad to learn about hubby getting on board (lol). I know firsthand how important that can be! Your situation almost sounds like it has the makings of a true vermicomposting love story! Awesome!
    Tams – sorry to hear about the Alaskan cold sweeping in before you were prepared! Assuming you don’t get anymore opportunities to build up a nice big system, what I’d suggest is heaping on as much insulation material as you possibly can so as to help ensure that the worms at least survive. They tend to be ok during the initial cold snaps of late fall, early winter. It’s when the really brutal cold comes that they don’t stand a chance without adequate protection.

    • John W.
    • October 30, 2012

    I live in FL…so i know what a true cold feels like..sometimes it almost gets down to freezing here 🙂
    But here is my follow up question (I won’t be doing any of these things cause my worm inn is inside my office)
    How do the worms gets oxygen? If I understood you correctly…by time you bury a bin to the vents…cover it with snow/hay and then put a plastic tarp over it…
    I am just curious how they can get enough oxygen to keep from getting anaerobic?

    • Joseph Zhang
    • October 30, 2012

    “Bentley on October 24, 2012 at 3:10 pm said:
    Recording is now available for download.”

    Perhaps I’m blind, but can you point me to where the link to the podcast is?

    • Joseph Zhang
    • October 30, 2012

    Ah! Never mind. With my javascript turned off, I didn’t see the player.

    • Joseph Zhang
    • October 30, 2012

    Turns out that your podcast is quite excellent. Even though you claimed to not be prepared, I think you did very well indeed. You’re a good talker 🙂

    • Bentley
    • October 31, 2012

    JOHN – EXCELLENT question! For systems you are simply overwintering to protect it’s not a big deal. Metabolism/respiration drop significantly so demand for oxygen is MUCH lower. Where it gets a bit tricky is with those systems we are trying to keep active. It’s important to allow at least some air in for sure! With my big winter windrow I try to keep a small opening down at the bottom corner of the tarp. I also just generally aim to open up the tarp on a fairly regular basis. I’m not going to claim to have a perfectly optimized system during the winter – but it does seem to do just fine!
    JOSEPH – glad you figured it out, and THANKS so much for the kind words. In some ways I’m kicking myself for not doing podcasts sooner (since I find it much easier/faster to talk about a topic than to write about it). Oh well – late is better than never! lol

    Next on the agenda – “Flow-through Vermicomposting”

    • Rich
    • November 3, 2012

    One thing I am surprised I didn’t hear to keep a worm bin warm in a garage would be to put it on a piece of Styrofoam so it isn’t on the cold concrete

    • Bentley
    • November 4, 2012

    Hi Rich – I would consider that one of many insulation strategies. You’d likely still need a heat source if temps dip pretty low.
    Definitely a good idea to make sure the bin is up off the cold ground though – thanks for mentioning that.

    • Garry - RedWormsBC
    • November 11, 2012

    Hey B!

    I just finished prepping the trench for winter, since the snow is coming. I took all the ‘finished’ pumpkins and chopped them all up, plus added all the various bits of house trimmings from the freezer (pumpkin guts from making jack o lanterns, salad trimmings etc) and it was a surprising amount!

    I threw it on top of the trench, since I already had a biiiiit of bedding on top, and then cleaned the entire yard of fallen leaves, small twigs etc. Threw it all on top of the N’s I had just added, and covered it over with a couple of tarps I found and decided to give a second chance to.

    It was a really nice bit of time to myself, reconnecting with mother nature in a way, and I gotta thank you again for inspiring me the first time (way back when); without that, I never would have had the beliefs and outlook on life that I do today.

    Thanks again bro!

    • Bentley
    • November 12, 2012

    Heya Garry!
    All sounds great – and I’m glad the approach as worked well for you. Funny – I was out doing almost the same thing yesterday and today! We had some REALLY nice weather, and it looks like it is going to be very short-lived, so I figured it would be a great time to get a thick layer of straw over my beds and to add all my chopped up pumpkins/squash.
    Like yourself, I definitely enjoyed the experience! Not enough outdoor fun as of late.

    • Robert
    • June 12, 2014

    Hi Bently.
    I live in northern Idaho zone 5 which means -10 F. I have a 15×34 framed greenhouse, still gets below zero in our long winters drag on. Last winter I built a 4×12 18 inches deep pit in the middle of the gh to build a rocket mass heater and then the project got put on hold. Spring coming I needed the space in the greenhouse so I filled the pit with half composted manure from my wives 10 goats. I mounded it so the deepth was 24 inchs, thru in some worms from the worm bin and covered the whole thing with landscape fabric and gardened in pots in it all summer. The compost got water from watering the pots and a year later the compost had sunk to about 4 inchs below ground so I pulled back the fabric to see what was going on and was pleasantly suprised when all I could see was castings and worms. There where 10s of thousands of worm and a layer 3 inches thick of pure castings. I plan to tend better to my new worm bin this year by feeding more often ( the hungry worms were small) and mound a hot layer on top this Winter. Thanks for the inspiration.

  3. Hey Robert,
    The worm & compost pile in your greenhouse sounds neat! Question: You did not find that the bin got too hot with a tarp over it during the summer? I didn’t quite understand what you meant when you said you “gardened in pots in it all summer”. Did the pot plants sit on top of the tarp and effectively shade it? I sure would like to hear if you are able to create heat for the winter from the compost WITHOUT killing your wormies. Good luck!

  4. Check out that a working vermicompost is not THAT cold sensitive…..
    If your bin is working well, at 10C = 50F the internal temperature is still 17C = 63F by microbial heat.
    This does work with a plastic bin of 20l already!

    So maybe the temperature in your garane is enough to keep them working… but think of intelligence of nature: I guess it is not bad to make it a bit hard for them to pass the winter and have a forced rest!
    But far from this issue: Indoor vermi is no problem at all, just protect against the small fruit flies…..annoying!

  5. I read a report on nematodes and confirmed it with a nematode guy, that they go through phases of life, and we agreed that redworms are the same. We theorize that cocoons set in large numbers in the fall in Michigan have an alarm clock set to the length of day. When that day arrives in the spring, your herd springs to life as newly emerging infants.
    It is essential that an outdoor bin be larger than 3’x3’x3′ as mine are. I dump the worm farms back into the compost bins, after harvesting the vermicompost. When I return from wintering in the tropics, I screen the compost bins through a 1/2″ screen to refill the worm farms.
    I still have many adult worms that survived the severity of winter, and an enormous number of cocoons that soon hatch.
    You should be researching biochar.
    We blend biochar and vermicompost for a product we sell.

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