Five steps to Hot Composting
Speed up your composting and kill pests and weeds.
Most of us start our composting career by using a Cold Composting techniques adding waste organic materials to a heap or bin as they become available. As we learn a little more, we try to add about equal parts of Greens and Browns and once the material is in the bin we often leave to decompose without further intervention. This allows us to spend more time growing and gossiping on the allotment. We certainly have time as cold composting can take six months to a year which is quite a delay if we want to produce as much compost as possible.
Hot Composting methods will provide compost more quickly with traditional hot composting producing immature composting in three weeks, or within six to twelve weeks if it is turned less often. However, hot composting does require more time and effort on the part of the plot holder, but it is not complicated.
Hot Composting methods will provide compost more quickly with traditional hot composting producing immature composting in three weeks, or within six to twelve weeks if it is turned less often. However, hot composting does require more time and effort on the part of the plot holder, but it is not complicated.
Bin Size
The bin, or heap, should be at least a meter square and preferable at least the same height. Size is important as there is a need to retain the heat produced by the microbial activity as they breakdown the plant waste.
Some source will advise using larger bins to provide their own insulation and I have seen eight foot bins in some gardens , but while these are good at retaining heat, they are very hard work to turn manually. Turning a bin seen to the left.
The bin, or heap, should be at least a meter square and preferable at least the same height. Size is important as there is a need to retain the heat produced by the microbial activity as they breakdown the plant waste.
Some source will advise using larger bins to provide their own insulation and I have seen eight foot bins in some gardens , but while these are good at retaining heat, they are very hard work to turn manually. Turning a bin seen to the left.
Insulating the bin helps to maintain the using solid sides, lining slated pallet bins with compost bags, carpet, tarpaulin, cardboard, or carpet.
Greens and Browns
Greens and Browns. Are necessary for the composting microbes to breakdown the organic materials. Greens are high in nitrogen for the microbe growth and reproduction as well as the production of the enzymes that break down the waste. While the carbon rich browns provide a source them with energy.
For normal garden waste roughly equal quantities of each are required. However, if there is a high fruit or kitchen waste content addition browns, such as woodchip, will be needed as a bulking to absorb excess moisture and retain air spaces in the material.
Greens and Browns. Are necessary for the composting microbes to breakdown the organic materials. Greens are high in nitrogen for the microbe growth and reproduction as well as the production of the enzymes that break down the waste. While the carbon rich browns provide a source them with energy.
For normal garden waste roughly equal quantities of each are required. However, if there is a high fruit or kitchen waste content addition browns, such as woodchip, will be needed as a bulking to absorb excess moisture and retain air spaces in the material.
Material size
When hot composting enough waste should be collected to fill the bin in one or two days. The waste should be cut into short lengths and brassica stalks crushed and chopped, I use long handled shears to cut the material and a hammer to crush it as it is added to the bin in alternate layers of browns and greens. This exposes a larger surface area to bacterial action. Larger pieces will expose less surface area and lead to slower decomposition. Many books recommend about an inch to an inch and a half in length but with thin stemmed materials I leave them at about six inches.
The layers will be mixed when the contents are turned. An alternative method often used on larger estates is the mix the greens and browns together in advance and then shred the mixed load using a shredder. Each layer should be watered as it is added to the bin.
When hot composting enough waste should be collected to fill the bin in one or two days. The waste should be cut into short lengths and brassica stalks crushed and chopped, I use long handled shears to cut the material and a hammer to crush it as it is added to the bin in alternate layers of browns and greens. This exposes a larger surface area to bacterial action. Larger pieces will expose less surface area and lead to slower decomposition. Many books recommend about an inch to an inch and a half in length but with thin stemmed materials I leave them at about six inches.
The layers will be mixed when the contents are turned. An alternative method often used on larger estates is the mix the greens and browns together in advance and then shred the mixed load using a shredder. Each layer should be watered as it is added to the bin.
Aeration
The purpose of turning the bin contents is to provide oxygen to the composting microbes. Usually, three or four bins are used in a row with material being passed along the row as it is turned and matures. Open fronted bins make access easier for turning.
Two to four days after the contents have been added to the bin they will have reached a temperature of 40-60 C, and the material should be aerated and mixed by turning . The best mixing technique is to transfer the material to an adjoining bin taking the material at the sides of the bin to become the core of the new bin. The temperature will drop on mixing but will start to rise again . The moisture content can be checked when the contents are turned (see left).
The temperature should be monitored, and the bin turned again every two or three days or when the temperature starts to fall until turning does not result in any increase. The contents should then be left to mature.
The purpose of turning the bin contents is to provide oxygen to the composting microbes. Usually, three or four bins are used in a row with material being passed along the row as it is turned and matures. Open fronted bins make access easier for turning.
Two to four days after the contents have been added to the bin they will have reached a temperature of 40-60 C, and the material should be aerated and mixed by turning . The best mixing technique is to transfer the material to an adjoining bin taking the material at the sides of the bin to become the core of the new bin. The temperature will drop on mixing but will start to rise again . The moisture content can be checked when the contents are turned (see left).
The temperature should be monitored, and the bin turned again every two or three days or when the temperature starts to fall until turning does not result in any increase. The contents should then be left to mature.
Moisture
Each layer of material should be watered when added to the bin and at intervals during the composting. A moisture content of 45% to 60% moisture is ideal. This is easily checked by squeezing compressing a handful of the compost. It forms a ball the moisture level is right if it falls apart it is too dry and if water runs up your arm it is too wet.
Each layer of material should be watered when added to the bin and at intervals during the composting. A moisture content of 45% to 60% moisture is ideal. This is easily checked by squeezing compressing a handful of the compost. It forms a ball the moisture level is right if it falls apart it is too dry and if water runs up your arm it is too wet.
Sponge test.! Compost should have a similar moisture level to that of a wrung out sponge.
Finished Compost
The compost is finished when it ceases to warm up when turned. At this stage it should be dark brown in colour with an earthy smell. It can be used as a mulch or left to mature for use as the basis of a homemade seed or potting compost. More details on composting can be found in a Gardeners Guide to Composting Techniques (Crowood Press).
The compost is finished when it ceases to warm up when turned. At this stage it should be dark brown in colour with an earthy smell. It can be used as a mulch or left to mature for use as the basis of a homemade seed or potting compost. More details on composting can be found in a Gardeners Guide to Composting Techniques (Crowood Press).
Rod Weston
Rod Weston is an organic master compost expert, who operates a composting demonstration site with over 30 composting bins, wormeries and cooked food composters at Stokes Wood Allotments in Leicester. He runs our NAS composting Facebook group and is also author of ‘A Gardeners Guide to Composting Techniques’ published by Crowood Press.
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