In my area, we get municipal composting. In the winter, we can leave a bin (around 5L) out, and once a week, they pick it up and compost it in their giant compost bins.

The problem is now that our temperatures dropped; anywhere from -2C to -25C. Even if I leave the compost bin out early morning the day of (although I usually do it the night before), the compost freezes solid. I'm not sure why; I suspect it's water from the denaturing organic material (greens).

I tried leaving the bin in the sunlit areas in higher temperatures (-2C), but to no avail. I tried leaving it in the garage, but that's also ice-cold. I intended to salt it, but I think that will destroy the compost value of it.

Is there any way to thaw/defrost the compost, other than leaving it in our house? It will stink. Right now, the bin is 50% full with a solid, frozen block of material.

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    Why exactly is the frozen compost a problem? Are you unable to get the compost out once it is frozen? – THelper Jan 8 '14 at 9:30
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    @THelper that's correct. The truck left my bin as-is because the frozen compost block refuses to leave the bin. – ashes999 Jan 8 '14 at 14:57

Since your bin is already frozen and 1/2 full, I would suggest a spade or pick to break up the block into manageable sizes that you can then remove from the container and transfer into a paper bag. Wood shavings for caged pets or barn animals, as well as non-colored and/or non-glossy newsprint will also do a fine job of absorption. You must mix it in thoroughly during the collection process though. Unfortunately there is no way to stop something wet from freezing in sub 0 temps. Your best bet is to reduce or dissipate the moisture content. Avoid cat litter (unless it is wood or corn based) and never ever use soiled cat/animal litter of any type.

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  • Are you suggesting that heavy use of newspapers can absorb much of the water and prevent it from freezing solid? – ashes999 Jan 7 '14 at 16:33
  • no i'm suggesting to reduce the moisture content to prevent freezing. anything wet in the elements will freeze... off setting the moisture from use of absorbent natural biodegradable/compost-able material will help to reduce the giant ice block you have. Remember green & brown when composting.. too much newsprint will reduce the organism's efficiency when multiplying to decompose it. – Phlume Jan 7 '14 at 17:10

So the concern is just that the municipality can't empty your bin because the contents are frozen solid, correct? How long does it take you to fill half a bin? I would leave it outside and keep filling it until it is full. Like most others, we are in a deep freeze here, too -- -11F currently. A warm up is coming, though, and the compost will unfreeze then. I wouldn't go through the trouble of chipping it out at this point - it will thaw next week for you.

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  • We're in the -20 to -30 range. It takes about a week to fill it, and that means I'm stuck. I need a way to defrost it. – ashes999 Jan 7 '14 at 16:33
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    Couldn't you just collect the rest in another, temporary bin til next week? i see you are in Ontario, and your temps will be above freezing by the weekend.There is just no way you'll melt it without bringing it inside. You could then line the bin, as other suggested, but it seems most prudent to find a way to wait out the cold. – michelle Jan 7 '14 at 17:49
  • This is not a temporary, once-this-week thing. This is a larger problem I will face all winter, until I get another compost bin (my 13L is full) and can afford to self-compost throughout the cold months. – ashes999 Jan 7 '14 at 17:56
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    Makes sense...seems the others' suggestions for either lining the bin or decreasing the moisture content are the way to go...or how about this - you could use your freezer to freeze the compost before you put it out. If you freeze it first, it won't stick to the sides of the bin (kind of like when you buy a bag of frozen chicken breasts, and they stay separate because they were frozen before they were placed together in the bag). – michelle Jan 8 '14 at 20:43

If you have leaf and yard waste paper bags and a pair of scissors you could trim one of these disposable and recyclable bags to fit inside your bin as a liner. This mostly keeps things from sticking to the edges.

Small animal bedding or kitty litter1 have low water content. It will bulk up your compost and soak up your compost liquid.

1 In my city, fresh or used animal bedding and kitty litter are acceptable in our green bin. As always consult your local city guidelines for the last word in what can go in the bin.

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  • cat litter is full of clay and chemicals. try instead hay or shavings for barn animals. small packs of shavings are available fot hamsters and gerbils. – Phlume Jan 6 '14 at 12:29

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