Experiment - we need to heat our compost pile up!

December 2023

As we are fairly new to composting and very new to hot composting we are learning as we go.  A generous supporter donated a compost thermometer and we have been dutifully taking the temperature of our compost every day since the thermometer arrived.  We were very excited when we hit 120 degrees so quickly but unfortunately since then the temperature has dropped off and we are no way near the required 140+ for hot composting.

Our internet research told us to add more scraps, to turn, to add water if the consistency is too dry.  Other advice was to make the pile bigger.  We have done all of this but to no avail.  As a result we decided we needed to try something new.

New design for hot compost pile - Greenwich Composting Project

Our research has suggested that aerating (or lack of) may be the problem.  Despite frequent  turning, our composting material is getting quite compacted and the smell is suggesting the pile has gone anaerobic.  Time to get inventive using this old pallet as a base.  Our mission: to build an aeration system with as little expenditure as possible.

Mariam Fahimi designs an aeration system - Greenwich Composting Project

We then purchased some plumbing pipes, cut them to 5' and lay them across the pallet.

We drilled holed every inch or so to allow air to escape.

The plan is build our pile on top of the pipes with the hope these will provide aeration. The hope is the heat of the compost pile will draw the air entering the tubes up through the pile, giving our microbes sufficient oxygen to work as hard as possible.

Mariam Fahimi with her new hot compost deisign - Greenwich Composting Project

On go the leaves as a base for our compost pile

Mariam Fahimi building her newly designed aerated compost pile - Greenwich Composting Project

Time to move the old pile onto the new.  This will take some time as our old pile had got quite big and heavy!

Greenwich Composting Project, new aeration design

Slow progress, I reckon we are about a third of the way there at this point!

Compost pile with aerating pipes at the bottom - Greenwich Composting Project

The pile is getting bigger.  We have to make sure the ends of the pipes are not covered!

Greenwich Composting Project, new aerated compost pile

We had to build some support around the pile to stop it collapsing. We used old tomato stands and netting.

Base temperature of new aerated compost pile - Greenwich Composting Project

The pile is not even at 80 degrees now.  We will check again tomorrow and hope it has increased!

12.04.2023 - Update!  We did not check the temperature yesterday as there was heavy rain all day.  Good news today however, despite the cold and wet weather the temperature is on the rise.  It was less than 80 degrees on Saturday, today it is 105 degrees.  Will check tomorrow and hope it continues its upward trend!

12.06.2023 - Update!  Temperature is still rising - today we recorded 116 degrees!

Steam rising!

Despite not reaching 130 degrees, the compost is very hot as evidenced by the steam rising following some aeration and turning.  I am not sure if the photo does it justice, but there was a lot of steam today and the warmth of the pile could be felt through our boots!


The compost continues to be active but is still not hot.  The highest temperature recorded since the last update is 116 degrees but shortly after reaching this level it dropped to 110 degrees and stayed steady.

It is our hope that the combination of more scraps added, some turning of the compost and the addition of the fantastic coffee grain donation today will make all the difference.  The temperature dropped following the aeration to about 102 degrees (the ground is around 34 degrees). Let's see what happens over the next week.  We have not given up hope of reaching 130 degrees!  As always we will keep you posted here!


OK so not great news regarding the temperature, but Rome wasn't built in a day!  As we have not managed to reach our target we decided to turn to the composting community for help.  The wonderful thing about the community is that it provides so much support and advice.  Two pieces of advice we received were to first incorporate a different source of browns, rather than leaves, something that holds its form a bit better - wood chips for example.  We will try this so if anyone in the neighborhood has spare wood chips please let us know!  The second piece of advice is to insulate as the temperatures outside drop with hay bails or similar.  We will also try this.  We will aim to mix the wood chips next week along with the new kitchen scraps.  Fingers crossed!


So, our experiment has not been a success so far but we have not given up.  We have since received more advice from the composting coalition suggesting that our piles had too larger surface area which allowed heat to escape.  Our old piles had a cone type shape getting narrower and narrower towards the top.  Thanks to some recent generous donations we have purchased 4 compost containers with the hope that keeping our kitchen scraps more contained with reduced surface area will help with the heat.  We have also added some wood chip.  Fingers crossed we have some success and rising temperatures soon - stay tuned!


Success!!! All the advice we received really helped! One of our two compost piles is now over 110 degrees and so our pile is active again!  Big relief. Our second compost pile needs some work as it is only about 60 degrees right now.  This week we added lots of kitchen scraps, wood chips, some suitable browns and mixed it well. We are hoping we maybe able to achieve warmer temperatures this week.  As usual stay tuned!!


More success!!!  One of our two compost piles has increased from around 110 to 130 degrees in the last three days which is huge for us!  Even more exciting, our second compost pile has gone from 60 degrees to around 110 in the last three days.  The temperature dial is moving in the right direction and we are feeling optimistic.  Once again, thank you to all the members of the Community Composting Coalition who offered all their advice, the key piece was keeping the compost more contained, reducing its surface area.  We will continuing adding to, and monitoring, these two piles and in a month will start on a third.  Feeling much more confident about regarding having finished compost come Spring!


So the compost piles are cooling off again.  Our hope is the bottom of our piles is beginning to look like the bottom of the pile in this image.  We have two large piles, the plan now is to stop adding to them and start a third pile.  In the meantime we need to get into a routine of regularly turning the two piles we have.  Give the size of them this will take some strength and time! As always we will keep you posted!

May 2024 - SUCCESS!! So after all our experimenting, turning and monitoring we finally have success!  We have three bins all at different stages of composting.  The first and hottest bin is over 140 degrees and is breaking down fast, the second bin is at the top end of the active range at 130 and the curing bin is warm at just over 80 degrees.  The curing bin is so close to being finished compost and we cannot wait to start giving finished compost to our pilot households who have supported us so much since we started this project!