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18 Day Hot Composting

Hot Composting, Step By Step

Preparations work

Locate your composting space in an area protected from direct sun light. Ensure to have a tarp or waterproof cover, available, to protect it from the rain. This cover will also assist in holding the heat in the pile.

To turn the pile effectively you will need to have access all the way around it. You also need a space, big enough, to turn your pile into.

The compost pile, that you are going to build for your 18-day composting exercise, cannot be built slowly, it has to be put together in one day. This means all the raw materials, to build the pile must be collected in advance an readily available. The minimum volume of your pile is going to be 1m3. The initial pile will likely have a greater volume than this because it will be very loosely put together and have an excess of air (which is good) this means at the very start your pile might stand 1.2m high across a 1.2m2 base.

If any of the material is particularly chunky, it might be a good idea to run it through a shredder first. We need to maximise the surface area of all the material this will increase the surface contact between the brown and green materials

Day 1

Have all your raw materials around you for easy access. Using a pitchfork or other suitable tool start building your pile. Put the materials down in consecutive layers of browns and green. Each layer should be put down about 10cm deep, lasagne style. It is best to start with a layer of browns. These layers will be broken up after the first turn but this is the best way to get an even distribution of the nitrogen and carbon throughout the heap when you are getting started.

As you are building the pile when you are getting to where the centre might be, you can include a composting activator. This is not absolutely necessary but will certainly help to kick start thing straight into a high gear. Activators might include comfrey, nettles, yarrow, dead animal, fish, urine, some mature compost.

Give the heap a good watering once it is complete, this ensures all the material in the pile has a coating of water. Initially, the bottom of the pile should be saturated. Care should be taken that the pile is able to freely drain.

Put a rain cover over the top of your pile. You need to make sure you are in charge of the water content and the process will be affected if it is open and can be soaked by rain.

The compost is then left for four days to do its magic. If you have mixed your compost correctly things should very quickly start to heat up.

Day 4

On Day 4 you make your first turn of the pile. At this stage, you need to check the moisture content. Moisture in the mix is very important, as it softens the material and allows microorganisms to move around. Not enough moisture and you will get very little activity (hence, very slow composting). Too much moisture and it fills all the area around the materials with water, this will limits the microorganisms ability to access any oxygen. The material should feel moist to the touch and when you pick up a handful and squeeze it you should maybe just be able to squeeze a single drop out. The mix should be as damp as a wrung-out sponge. It should feel wet but you should not be able to squeeze an excess out water. If it is too wet you might want to consider putting some sticks under the next pile you build to see if you a can improve the drainage.

During the last few day, the microprobes will have been extremely busy in the pile and they will have burn through all the available oxygen in the heap. The action will also have mainly been concentrating on the centre of the heap; the outer surface of the pile will be largely cool as it is exposed to the outside environment, little if any composting activity will have taken place there.

It is important that you turn the pile correctly. We need the outermost layer of the heap to become the centre of the next heap. The pile will begin to stream very noticeably as you start to expose the centre, that will be cooking hot inside. You will really be able to feel the heat coming off the pile. To turn the pile effectively you need to think about effectively peeling the whole heap, skimming off only the top layers at a time. It is best to start at the top and work your way down and around. The new pile being created also needs to be built out in expanding layers up and out from the centre up. Once you have finished all the outside of the original heap will be on the inside and visa-versa.

Having lots of fresh material and abundant air the pile will quickly fire back into life.


Turn your compost heap again using the same method as before. It is between 6 to 8 days that the compost heap should reach its maximum temperature. As a rough guide if you can put your hand into the heap up to your elbow then it’s not reached 50 0C but if you have turned your pile correctly and added all the right mix it will be too hot to put your hand into the pile. An ideal temperature of 60-65 degree C, if you have a compost thermometer you will be able to check this.


Turn your compost heap again. From this point on your heap should begin to slowly cool down.

Continue to turn your compost pile every 2 days, on days 10,12,14 and 16.

DAY 18

The pile should now be just warm, it will be dark brown and smells good. There will be nothing from the original contents that you will be able to recognise.

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