So, Sunday, like I told you, I put the market green scraps in the compost pile. Yesterday I added wet, shredded cardboard. Today I went up to see how it's doing and as I opened the compost bin, I saw lots of condensation on the lid, so much that it dripped down back into the pile. Interesting. Something is definitely going on in there. I touched the top of the pile and could already feel the heat. I went to get a thermometer. I don't have a compost thermometer (yes, they exist), so I just used the one I have for making candy...

I took the temperature in one of my flower pots, just as a control test: 14°C (57.2°F). But right in the center of the compost pile it's already 35°C (95°F). Fahrenheit temperatures are so much more dramatic! (Maybe because I understand them viscerally.) Around the edges it's only 30°C (86°F). That was at 9:30am. I wonder how it will be later in the afternoon when the outdoor temperature rises a bit more. It's 13°C (54°C) right now outside.

I'm going to keep going to the market for more green scraps until the compost bin is totally full, even though theoretically you're not supposed to add more once you've started. I think that the more material there is, the more insulated the central part will be, and the higher the temperature will go. No stirring for the moment.

According to the Cornell compost scientists, “a well constructed compost system will heat up to 40 or 50C within two to three days”.

Fun fact: perhaps you've seen how they stir hay around and then leave it out in the sun for a while before they bale it and store it in the barn—that's because if they leave it too green, its temperature will rise and it can even burst into flames. 

(I used to have a barn full of hay in Massachusetts. Sometimes I put my hand in the bales of hay to make sure that my house wouldn't burn down.)