You might have to take the bin to a warm room to "wake up" the MO. Once the bin is active (warm), you can move it back to the cold cellar, making sure there's always food in it.
However, it also depends on the size of the bin. Bigger bins maintain heat longer than smaller bins. If it's a small system, you might want to wrap the whole thing in an old blanket or similar.
People are saying that rice will heat up a bin in no time but it never happened in mine. Don't know why.

Insulate the bin and use a light bulb.

Quick and easy: Put a seed starting heat mat under it for a few hours.

I saw somewhere on this site that someone used Christmas lights to heat a bin. They were the kind with the lights inside a tube.

It takes significant amounts of food in good green/brown proportions to generate much heat, let alone sustain it. It's one reason why a regular compost bin is supposed to be made all at once, at least 3x3 ft, and have good green/brown proportions.

I keep my worms in a 2' x 2' wood bin, with a wooden lid. I keep it in my shed, which pretty much reaches the temps of the outdoors. During the cool season, I keep it wrapped with a water tank insulating blanket, plus I leave all the castings from mid summer until the next Spring. I think that may give them enough protection from the cold, as they have survived quite a few nights in the teens. I did have another bin the first year I started, and I used the light bulb idea, but the bulb burned out, and they perished. So you might want a backup light, just in case.

Hey, Eq--did you ever find a formula for this?

I _really_ like the idea of a non-powered heat source for a wormery (even if it's only theoretical for me this season). And if someone else did the first numbers--that's a hint!--then I could test those in bins fed with composted bokashi...

DSF

If you want to heat it 'organically', you might want to throw in some bread or granola. I find that a couple of handfuls of granola, or some pizza crusts or rolls also warms up my bin: it starts acting like a 'hot compost' system.

There's information at the thread below

Here is a link that might be useful: Adding rice to generate heat?

dsfoxx: Nope. I have tossed in bread into the tiny bin in an attempt of heating but I did not notice any heating. Bokashi is an exciting concept. Especially for items not yet ok for worms like meat scraps. No reason to have only oxygen breathing bacteria working for us. Along with that is Kombucha. I tossed the worms the SCOBY ("Symbiotic Colony of Bacteria and Yeast") or zoogleal mat and they seemed ok with it. Also added in is biochar in order to have lots of nooks and crannies for the weebeasties. The worms might like to dine upon weebeasties. I would like to see maybe a hierarchy where food and other waste is first put to it's highest use. Gleanings first to people, then to animals, then to BSFL, then worms or bokashi. Not having those my scraps go right to the worms. Cabbage type items and tree leaves to the outdoor compost heap. Even cardboard waste can be first used as animal or chicken? bedding before going to the worms. Maybe soon bokashi will be more available to the common man. It would be great if newspapers and egg cartons would arrive already impregnated to be used as bokashi covering. Bokashi juice and vermicompost tea are maybe two sides of the same coin. Maybe toss a few pieces of biochar into that bokashi as it is made. More surface area for the oxygen avoiding crowd. I would like to toss two cups of bokashi into a tiny bin to see if it would warm the worms toes. It would possibly be a balance to avoid possible chain of pearls or worm loss of bodily integrity. Since the forum of the layered worm systems (worm factory?) are so familiar to people, I would like to see bokashi used in that type of a system.

Lowes sales a plug in meter that will put power to a lamp, if the temperature drop below 40F at any time.
I have a water pump 16 miles from my house & never had a frozen pipe in 4 years, temp. got down to 17F & the water flowed as if it was summer time.
This will keep your worms from getting to hot on warm days also.

I've tried bokashi* in my tower wormeries--not too dissimilar from worm factories, though the layers are a little deeper. It works if you're willing to feed from the bottom rather than the top, and if you mix the bokashi with dried leaves or coir, it does heat up. In my case, too much--though I suppose if you were to add smaller volumes of bokashi to dry matter, it might serve. Two cups of bokashi in a three gallon bucket, with an equal volume of coir, will produce enough heat to be perceptible from the outside; wetter conditions limit the heat some, as will the choice of dry matter, but I don't know how much.

As for food hierarchy, there are people feeding bokashi-fermented food wastes to chickens(!) and pigs. Restaurant waste in commonly used as pig fodder in the US, but distance is a limiting factor; the bokashi added as a short-term stabilizer, so foods can be collected and transported from city restaurants/homes to countryside farms. I want to see a lot more of that; bokashi could be used to make urban compost collection more feasible... Like you, I'm farmyard-critter free, so I'm just feeding buckets.

_Love_ the idea of microbe-impregnated paper products. Might be time to dig up my paperboard recipe and give it a try.

Haven't gotten much into biochar yet, though this may be the year. Think I'd add it after fermentation, though.

Hmm. Does biochar act as a dry material in composting?

DSF

*microbially fermented kitchen waste, for readers not familiar with the term

"Does biochar act as a dry material in composting?" I feel it is neither food nor bedding. I would clasify it the same as the bucket or bin. It is a surface that gives a place for interactions to happen in the slime upon it at a micro level.

Maybe think of it as the wee little pigs. The straw (cheating a little here) would be the food. The wood would be the bedding. And not finding enough surface area on either of those the biochar would be brick with lots of nooks and cranies to house the wee wee wee little beasties.