Thursday, May 17, 2012

Hot Composting Secrets for Faster Finished Compost

Hey, hot stuff.

Are you hot-to-trot for that first satisfying scoop of dark brown crumbly finished compost? You may consider “hot composting.”

Basically, this method, also referred to as batch composting or active composting, employs every possible advantage to create the optimal environment for microbial activity within a compost pile. That microbial activity generates heat causing the pile to increase in temperature and rapidly decompose.

Translation: hot composting is a lot of work but you are rewarded with finished compost very quickly.

People using this method, let’s call them “hot composters”, have been known to generate finished compost in as little as three weeks!

Hot diggity dog, let’s get started.

  1. Stockpile materials. Add all the material at once instead of building a pile gradually throughout the year. You can save food scraps in the freezer, hit up your local coffee shop, and stockpile leaves and yard trimmings until you have enough for a pile.
  2. Bigger is better. Hot composters build piles that are at least 3 ft x 3 ft or larger. If you are using a black plastic bin, fill it almost to the top if possible.
  3. Balance browns and greens. Add three parts brown stuff (leaves) to one part green stuff (food scraps). The perfect mix of carbon and nitrogen will make your pile sizzle. 
  4. Chop everything up. The smaller the pieces, the faster the microorganisms will decompose everything. Run over the yard trimmings with a mower and chop up the food scraps before leaving the kitchen.
  5. Boost microorganisms. Several shovels of finished compost will inoculate the new materials with microorganisms.
  6. Mix materials. Before you put the stockpiled material in the bin, mix all the greens and browns together. This will make sure all the slow decomposing browns have some green buddies to help them out. 
  7. Ban branches and unchipped wood. These items decompose too slowly for a hot composting pile. Chip the branches and sticks into small pieces before you add them.
  8. Consider airflow. Keeping the pile hot requires good airflow. If you place a layer of wood chips or straw at the bottom of the pile before adding your mixed materials, passive airflow will make turning more productive.
  9. Water. Keep your pile as wet as a wrung out sponge
  10. Turn weekly. Hot composters know that frequently adding air to the pile will keep those microorganisms chomping away.
Most of us will not use all of the hot composting methods nor do we really need finished compost every three weeks. But we can be hot composters some of the time by stealing a few of their tricks to heat up our compost piles.

I’ve never tried the passive airflow idea (#8) but the next time I build my pile, I’m going to add a bottom layer of straw and see how it works.

Will you try any new hot composting tip? Let me know in the comments.

Don't cha wish your compost pile was hot like me? Don't cha?
A hot compost pile from the ladies at Compost Gardening.


  1. If I decide to start a hot compost pile from scratch, where can I buy several shovels of finished compost to inoculate my pile (#5)?

  2. That's a good question. I know Marvin's Organic Gardens sells compost. You could also use a few shovels of really good garden soil.

  3. - the black bin filled to the top makes no air flow for the pile, right? how can that work?

  4. You're right, the more material the more difficult the airflow is. That is one reason you need to turn the pile every week with this method and also why they recommend having the material on a bed of straw or wood chips to encourage passive airflow from underneath. If you have enough shredded leaves or paper in there you will also encourage more air pockets throughout the pile.

  5. I am a first time composter with an Earth Machine bin half full of compost that I think is pretty close to ready. I have a few questions, though. (1) I have always kept the lid on the bin and have never added water - my compost might be a little dry. Is it too late now to add water? I want to plant tomatoes and peppers pretty soon. (2) I have been stockpiling kitchen scraps in 2 kitchen collecting bins, but I have kept these at room temperature. (I didn't want to add to current compost since I think it is ready.) The contents of these bins are, of course, starting to decompose - there is a little bit of mold and some stuff liquifying. Is it OK to use this in a new compost bin or should I throw it out and start over? (3) When planting with new compost, how much compost should I add and how much of the soil I dig up prior to planting? My yard soil seems very heavily clay. Thanks so much for all the help!

  6. Great questions! 1)if you think the compost is pretty much ready, you do not need to water. If you start digging into it and find it is not finished then add some water and keep composting. Your pile may be getting enough moisture from the food scraps you have been adding. 2) If you are going to start the new pile soon, definitely use your stockpiled food scraps. They are already starting to compost in the kitchen collector. But if they really start to smell before you get to the new pile, you may want to throw them out, not because they will hurt the pile, but they may become annoying to you! 3) You will probably harvest at most one wheelbarrow full. When I add compost to amend my heavy clay soil, I tried to add a few inches at least and then worked the compost in with a shovel. No need to remove the heavy clay soil that exists. Hope that helps!

  7. Does anyone have a wood chipper they can recommend? I am interested in getting a small one so that i can make my own mulch - my yard isn't very big but we seem to have an endless supply of small branches. Ideally, I would like one that will also shred leaves for my compost pile.

  8. Very weird but effective: occasionally pee on the compost. It sounds crazy but it works. I would advise doing it when things start to break down, but not near done or raw.

    1. Urine is very high in nitrogen so I can see how it would be effective. (:

  9. Thanks for the article, loads of great information.

  10. We made a great leap forward with our composting when we got a power mower and noticed that the pile of grass clippings we dumped in our backyard reached a temperature of 135 degrees. I have been having difficulty getting a mixed compost pile to go above 120 though.

    I sprayed every layer as I built my compost piles, and the moisture meter I stick in them is now maxed out at "Wet" so they may need to dry out a little.

    I also think my piles may not be quite big enough - in this case not high enough. I am finding bigger piles extremely difficult to manage. I have been forced to abandon bins because I cannot get inside them to turn anything, and have had to rebuild my piles in the backyard, outside of any containment.

    1. Anywhere between 90 and 140 is a good temp for a pile, so you're doing great. You may need to break up the material smaller if the pile is difficult to manage. I know that is more work, but if it is important to you to have finished compost sooner then it may be worth it.