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Hot Composting vs Cold Composting

Keith Hardy - Bio Photo
Keith Hardy
Senior Editor

Keith has been involved in the gardening and landscaping industry for the past 21 years. From a jobbing gardener to running his own landscaping services....

There are several ways that you can compost but probably the two most common ways are the hot and cold composting processes. When it comes down to choosing between hot composting vs cold composting much will depend on circumstances, time both your time and the time it takes to get to a finished compost state.

Hot Composting vs Cold Composting Chart

Cold CompostingHot Composting
Pile size3-4 ft wide and high3-4 ft wide and high
MaterialAs isCut into small pieces
Pile constructionLayered Brown/ GreenMixed together
Carbon/Nitrogen ratio30:125:1
MoistureKeep moistKeep moist
TurningInfrequentEvery 2-3 days
Pile temperatureNo need to monitor130-150 ° F
Time to finished compost3 months – a year3 to 4 weeks
Kills pathogens and seedsNot that effectiveKills pathogens and seeds
Winter CompostingYesNeeds insulating

What is Composting?

Composting is the process of breaking down organic matter (such as leaves and twigs) and kitchen scraps (vegetable peelings)  into a finished compost. This is achieved by the activation and the cultivation of microbes (bacteria) present in these materials which produce a chemical reaction, caused by the mixing of nitrogen and carbon-rich materials with air and moisture. The microbes then cause the materials to break down into a finished compost, sometimes referred to as ‘black gold’. 

Of course, while you could buy your prepared compost at your local Garden Center or even supermarket the majority of gardeners prefer to make their own using one of the composting methods.

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Not only is great satisfaction garnered from doing it yourself but you are also getting rid of your organic material and kitchen food waste in an environmentally friendly way. In addition, it allows you to regulate the composting process and provides you with a better understanding of what you’re putting on your plants and lawn.

Composting Processes: Hot and Cold Composting

There are several methods of composting but the two most common are hot and cold composting. Both methods allow composting of a wide range of materials (a list of what can and can’t be composted can be found here). Both are environmentally friendly and end up producing high-quality finished compost.

Cold composting

Constructing a Cold Compost Pile

Cold composting is the simplest and most uncomplicated way of composting, and the resources you will need are likely to be numerous and readily available. Approximately a third of household garbage consists of food leftovers and yard waste, the bulk of which may be composted, according to statistics. 

In general, cold composting ratios are not as critical as they are for hot composting because of the lower temperatures involved. Cold composting though will work much better when the brown and green materials are used in the right proportions.

A suitable mix should consist of approximately 30% brown (dry)  materials (such as leaves) and 70% green (wet) components green materials such as kitchen scraps.

To build the pile you layer the brown and green materials creating a pile around three to four feet wide.

The great thing about cold composting it really is a set-and-forget process. You can just leave the pile and cover it over with a tarpaulin in winter and the material will gradually break down. It can take though anything up to a year to decompose. The process can be speeded up if you turn the pile every couple of weeks. You can read a more detailed examination of how to cold compost and get the best results here.

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Hot Composting

hot compost core temperature

Hot composting in comparison needs a lot more of a controlled and hands-on process, The trade-off is that you are going to see finished compost in between 4-5 weeks.

The temperature is everything when it comes to hot composting. It is a method of making compost in less time than the cold composting procedure. It entails heating the compost pile to a high enough temperature while allowing for regulated airflow.

The ingredients are combined with hot composting. To achieve this efficiently, use smaller pieces of material than you would with a stacking approach. The greater the quality of the produced compost, the richer the combination of components.

What is important is the ratio of carbon-rich materials to nitrogen-rich materials and this is key to generating the required heat inside the pile for the process to work. Generally speaking, you would want a ratio of 25:1 carbon to nitrogen, the more nitrogen the hotter the pile.  

Your compost pile size should be around three to four feet wide and as high again once assembled. You then need to monitor the temperature of the pile which needs to be in a range of 130-150 F  and the pile moist. To keep this temperature up the pile will require regular turning every two or three days.

One distinct advantage of hot composting over that of cold composting is that it is far more effective at destroying pathogens and seeds. The heat generated inside the pile should be hot enough to destroy these. Ideally, you should not put diseased plants or grass clippings in a compost pile but sometimes it happens. Again, you should avoid putting seeds in a compost pile as if they survive they will likely sprout.

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In winter hot composting becomes more difficult due to temperature loss. However, if you insulate your pile well you should still be able to hot compost. You can read a more comprehensive guide to hot composting including detailed information on ratios and how to get the right ratio for your hot compost pile here.

Summary | Hot vs Cold Composting

As you can see both methods are fairly easy to implement. You don’t really need any special equipment except perhaps a compost thermometer and there are ways to even avoid buying this.

Cold composting is more conducive to all-year-round composting but if you can insulate your pile well enough then you can still hot compost in the colder weather.

The principal difference between the two methods is a question of time. Time in two senses, the time it takes to create the correct environment for and manage your compost pile and the time it takes to get a rich finished compost. 

Irrespective of whether you need speedy results or can afford to let compost “happen” at its own pace both processes result in high-quality rich compost for your garden.

Keith Hardy - Bio Photo
Keith HardySenior Editor

Keith has been involved in the gardening and landscaping industry for the past 21 years. From a jobbing gardener to running his own landscaping services. He is now dedicated to bringing you the latest in gardening news. Read more

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