Investing in a hot composting bin can seriously reduce the amount of waste that you send to landfill. You can add all kitchen waste, garden clippings, even cat litter and dog waste. A bin is easily accommodated in a small urban garden, where it will produce good quality compost in a fraction of the time taken by a traditional compost heap.
What is hot composting?
Hot composting works in a different way to the usual compost heap or bin. In a normal compost heap, like in the image below, the compost is broken down by a mixture of microbes and mini-beasts which can take many months, depending on the material being composted. The temperature of a standard compost heap reaches no more than 20°C which is much lower than a hot compost bin, which operates at between 40°C and 60°C.
I am a big fan of the traditional compost heap as they support a myriad of biodiversity and over time make beautiful compost. The main drawback is that they take up valuable space, which can make them difficult to accommodate in a small garden. The other issue is there are limits to what you can add to a compost heap. In terms of kitchen waste, only fruit and veg peelings are safe to add - any other kitchen waste (cooked food, meat, fish etc) will encourages rats. Persistent perennial weeds, such as bindweed and ground elder, also should be avoided, as the temperatures created in a heap are not sufficient to kill off the root system.
The hot compost bin
A hot compost bin is a self-contained and thickly insulated unit, typically made out of a material which feels a bit like polystyrene. It is about the same size as a wheelie-bin and is impervious to the attempts of burying rodents, so you are not going to come face-to-face with a surprised rat, when you open up the lid. This means that you are able to add all of your kitchen waste, including meat, fish and bones.
The bacterial breakdown of material produces a very high temperature which greatly speeds up the decomposition process, meaning that compost can be produced within 30 to 90 days. This high temperature also destroys perennial weeds, diseased material and fly eggs, meaning no fruit fly swarm as you open the lid.
Hot composting is easy and you don’t need to be a composting expert. For every addition of food and garden waste, you need to add approximately half the same volume in paper, which can be shredded documents, newspaper, torn up egg boxes or toilet rolls. The paper helps to absorb the water vapour which is released and so prevents the compost becoming a big blob of slime. You also need to add a small volume of a bulking agent such as wood bark (or an equivalent) which helps maintain the air spaces in the compost, enabling the aerobic bacteria to function. There is a thermometer embedded in the lid, so you can monitor the temperature as it rises. Once the temperature is above 40°C, you can add meat products.
There isn’t really much not to like about hot composting. My only grumble is the cost of a bin will set you back about £200, which is quite an investment. Arguably, you can offset some of this as you will be able to produce some of your own peat-free compost, rather than wholly relying on garden centres.
Hot composting hasn’t changed my need for a cold heap and I have a wormery too. It has however helped me deal with the volumes of garden waste my garden produces, as I was constantly waiting for one heap to decompose, before I could start another. The biggest positive has been turning products destined for landfill, into a useful garden product and who couldn’t be happy about that?