Winter Worm Composting / Hot Compost

[Kevin R]

This will be my first winter with a worm composting bin outside. I often hear about the dangers of hot compost when you stir too many food scraps. Would it be possible to do this on purpose during the winter in order to keep the temperature higher? Has anyone attempted this and have worms survive? I am in Tennessee, Climate Zone 7, so we don't have many freezing days.

[Mark from Kansas]

O.K. Kevin
Yes. What I do in the winter is add more fresh nitrogens or greens. I also have a simple heater that I use that my wife made BEFORE anybody else (check Bently's site). Here in Kansas during the winter, I have had temps in the single digits in my garage. The bin never got below 65 degrees. Now this past summer the garage got over 100 degrees but the bins never got over 75 degrees. I precomposted the feed stock by freezing it and then letting it thaw out before I added it to the bin, that way there was no decomposting heat energy. I also left the lids off and covered them with burlap. Evaporation helps cool the bins as well, much like humans when they sweat. I don't see you having any problems. Research and common sense will help a lot.

[Kevin R]

Thanks for the response. What would work for coverings besides burlap?

[Sue]

Wet newspaper, wet cardboard, or even wet old t-shirt will do.

[Robert Oats]

I am doing some basic research at the moment.

Basic principle is the mixing of a carbon with high nitrogen produces heat with the correct microbes.

I have been using very thin layers of mouldy bread crumbs about 3 - 5mm thick covered by a layer of shredded newspaper 75mm thick and it has maintained the area at around 25C for 5 days so far. The shredded paper has kept the heat in very well. As the temps start to drop I will monitor the system and adjust layer thickness to try to maintain the system.

Using bubble wrap around the system would also work for insulation. Hardware stores in the UK stock rolls of it for green houses. Anything that will trap a layer of air should work because static air is a poor thermal conductor.

[HH]

Robert - please keep us updated on your heating methods/experiments. Regarding the 25C you were able to maintain - what have the outdoor temps been and what type of container are you using?

[John V. Anderson]

As worms eat the burlap I've turn to rinsed out used pieces of carpet that work well for years and years even outside(nap up)

[Andrew]

I'm having mixed results with hot composting to keep the squirm warm. One problem is that it's hard to judge what's in my pre-compost mix. It's never the same C:N ratio. It helps to add a thicker layer of food stock (2" covering 1/4 of my bin) and then to really pile on the top bedding. Since leaves are currently plentiful, I've increased the top bedding to a 6" layer of leaves. The latest feeding has stayed above 70F for a few days while night temps are in the 40s.

[John V. Anderson]

I have a outdoor worm farm in Colorado at about 1800 meters and and it hit -25F here last week and my worms are fine. I don't have anything plugged(carbon foot-printed) in but my harvesting equipment and a radio(on solar). It is all heated by volume and passive solar. They slow down in the winter but so does business and their back like garbagebusters in March. I taught my Mom (rest her soul, not her spirit)how to do it in northern Minnesota. The trick is insulation and full sun southern exposure with some attentiveness to when the sun is out or just a large volume of material. If you have an established outdoor bed, with good venting hot compost won't hurt them, they do have the ability to move. What did they do with out us for 600million years for cripes sake. Fourteen years of mostly outside beds here and its my living so I don't take chances on losing my herd. Just because we build our houses so that we are beholden to the polluting power companies forever doesn't mean we have to do the same with my worm-beds. See my website for ideas.

[Andrew]

John, it's much easier to get hot composting going in my outdoor compost bin. Like you say, it just needs a large volume of material. There are "wild" worms in that compost bin, but not by design. The worm bin I was referring to is a relatively small (36 gal.) flow through that is fed maybe a gallon of material at a time. Neither bin is consuming power of any sort.

[Stacey Keller]

I kept a bin outside for 3 years here in virginia. It was a large bin from Lowe's, maybe 30 gallons, and it did fine. We had some really hard freezes, down to the teens and lower. I found that the worms burrowed deep down and weren't as active as they are are in warm weather. It had a lid and drainage holes of course. I didn't feed much in winter and by spring I had compost to harvest. I had some trouble with raccoons trying to chew their way in but the plastic was too tough for them I guess or the rounded edges kept them from getting a good hold on it. If you start it now before the weather gets too cold you should have a good colony going to winter over.

[Dilli]

Hi Stacy,

I am in VA and thinking to start vermicomposting. Where can I buy or get the worms locally?

Thank you.

Dilli

[Gardener Larry]

I have a slightly insulated FT bin that I just, 3 days ago, moved into the insulated (but not heated) detached garage. I have been running an experiment for the last 13 days experimenting with adding rice to heat the bin. You can check out all of the details here.
Many people say to be extremely careful with rice, but there doesn't seem to be much heat being generated. Although the temperature does seem to be warmer than the ambient temps on the whole.
My guess is that when the bin temps are a bit warmer (75 +) that the environment is much more conducive to the bacteria and they multiply out of control raising the temps beyond favorable conditions.