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Will My Compost Catch Fire?


January 31, 2019

I am interested in hot composting due to the fast turnaround. The only shady spots in my yard are currently next to the house. I know it's rare but I hesitate to put the tumbler next to the house in case it catches fire. I could put the tumbler in a corner of a fence and use a tarp to create some shade which as I understand is necessary to avoid overhearing in the summer? Does this sound reasonable?

And with hot composting is it correct that I would not be able to add more materials once I get it started? I generally have a small steady stream of materials so it would take a while to build up a lot.

Thank you again!


Answer by RR: First of all, I would not worry about your composter catching fire.  The reports of compost piles catching fire are associated with large facilities that have sufficient mass to potentially generate a condition that could cause combustion. But generally the reports of compost fires are way over exaggerated.  Your tumbler will hopefully generate some heat, but the amount of mass that fits in your tumbler will not be enough to sustain that heat for more than a day or two, at the most – to reach the desires 130 degrees +, and sustain it for the desired 5-7 days, you need at least a cubic yard, which is likely much bigger than your tumbler.

Secondly, a small steady stream of materials isn’t necessarily compatible with hot composting.  But don’t despair - there is nothing wrong with using your tumbler for “dump and run” type composting. As long as you add a mix of greens and browns and keep it moist (wrung out sponge) it will decompose, but more slowly.  Some people think you need to turn it every day or so – once/week is better. Just don’t expect it to generate a lot of heat. So often I hear people say, “my tumbler is not working.” My response is, “How do you know? Have you cleaned it out lately?” Maybe once or twice/year you should empty it, screen out the decomposed material (you’ll be surprised how much there is) and put the leftovers back in to continue decomposing.

Response from Questioner: Good to know. The reason I was hoping for faster turnaround is because I know we'll be moving in a little over a year so I didn't want to start something I couldn't finish. If I end up with some leftover partially broken down waste maybe I could drop it off at soilutions or bury it. I was kind of interested in the dig a hole and throw it in method but my dogs might like that idea too much as well.

Response by RR: Keep my email address.  When you’re ready to leave, I’ll take your partially decomposed materials…for free.  Soilutions will charge you $6.

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