Compost Bin

Sally212

I have a standard, 2 compartment, wooden compost bin which I cover with a sheet of plastic.  I mix and move my compost about every 2 weeks but as I've been using a lot as a mulch lately, I've been doing it more often.  I was moving some today, from one side to the other and the centre of the heap was actually burning.  The compost was almost black and it was smouldering.  Is it in danger of actually catching fire ?  I am planning on watering it every day to keep it cool until I have figured out what I should be doing.   Any advice will be appreciated.  

BenCotto

I have a bin that’s sometimes smouldering hot. I have never been concerned for one second that it constitutes a fire hazard but I would be interested in being proved wrong.

Sally, all I would say to you is stop being so diligent! My bin gets turned about once in its lifetime and I feel it still ought to be grateful. Your bin, Sally, is constantly being activated so gets hotter more quickly and will decompose faster. Think of it like poking an open fire.

Sally212

Thank you BenCotto.  I feel more relaxed now.  With the hot weather we have at the moment, I had visions of walking out to a blazing compost heap :-)  

PurpleRose

Hi

My bin has never been hot but at the weekend, we cut the grass and put the clippings I the bin. Yesterday, I put my hand in the bin to level it out a bit more as it was heaped too o e side and the heat from under the top of the clippings was really hot. The grass had gone a yellow and brown colour. I was quite surprised as I have never known this to happen.

A good fountain of knowledge around composting it @Wilderbeast and a few others may know some more

Sally212

Hi.   Thank you PurpleRose.  I've only taken up serious gardening since I retired, 3 years ago and its taken me over 2 years to master making compost.  I see it a bit like making a cake....  you wouldn't just put flour, egg and sugar in a bowl and then cook it without mixing it up first.  I have found it's the same with my compost, the smaller the pieces and the more I mix, the better the compost.  

PurpleRose

I have found I have learnt as I have gone along @Sally212 there has been a lot of trial and error and of course the ingredients are important to keep the balance right between greens and browns. I agree smaller things added break down a lot more quickly and a good stir around gets air in it which helps to mix up the layers of greens and browns.

Wilderbeast

Hi @Sally212 are you sure it was burning and not steaming ? Ive had my heap up to 90° but steam is then pouring out when you dig in it and the heap dries out very quickly. I have heard of compost that has combusted and my dad had a muck heap bust into flames (we lived on a farm so it was huge and very stinky). You seem to be doing it all the right way, I would water the compost as you turn it as loads of moisture is lost from heaps that are really hot. I run my sprinkler into the heaps as I turn it. I chop everything up with the lawnmower which definitely speeds things along, also if they are that hot you can easily add all food waste as its broken down very quickly I blend up all the food waste so it goes in as a slurry and it disappears in no time. Keep it up, composting is very addictive

Blue Onion

Depending on your compost mix, it could catch fire.  When I was a kid in Pennsylvania, farmers round hay bales out in the field would occasionally catch fire when they baled the hay too damp. https://ext.wsu.edu/hay-combustion.html  It was quite exciting, when it happened in the field near our home, with fire trucks and such putting it out.  It's possible your compost was burning, under specific conditions, but rare.  Could also be steam and black mold?  Piles of cut grass can get extremely hot in the middle when stacked a few feet deep.  Best get some more browns in there.