Hot Composting 101: Everything You Need to Know


Welcome to the fascinating world of hot composting, a powerful and efficient method of transforming your everyday kitchen and garden waste into a rich, nourishing supplement for your soil.

Hot composting, as the name suggests, involves the breakdown of organic waste at relatively high temperatures, typically between 43°C (110°F) and 66°C (150°F). This process is driven by thermophilic (heat-loving) bacteria that rapidly decompose the waste materials, producing compost in as little as 90 days.

Unlike cold composting, which can take anywhere from 6 months to a year, hot composting is a much quicker process. It provides faster results and a more effective break down of tougher materials such as small branches or corn cobs. The heat generated in hot composting also kills weed seeds and many pathogens, ensuring your finished compost is of high quality and ready for use in your garden.

On the other hand, it’s essential to understand the potential disadvantages of hot composting. One of the most prominent challenges is the need for careful maintenance. To ensure efficient composting, the bin must be turned regularly to maintain good airflow, and the compost heap needs to be of a specific size to retain the heat. It also requires a balanced mix of ‘green’ (nitrogen-rich) and ‘brown’ (carbon-rich) materials, which can sometimes be challenging to manage.

Despite these challenges, hot composting provides a multitude of benefits over a cold compost heap. Not only does it convert your kitchen and garden waste into valuable compost, reducing landfill contribution, but it also enriches your garden, promoting healthier plants. The speed and efficiency of hot composting make it an appealing choice for many gardeners.

Whether you’re a seasoned gardener looking to switch composting methods or someone new to gardening trying to figure out the best composting method, this article will provide a comprehensive guide on the intricacies of hot composting. Let’s dive deeper into this sustainable and eco-friendly process.

Basics of Hot Composting

Understanding the process of hot composting is key to achieving the best results in your garden. The process of home composting begins when a mix of green and brown compost materials is compiled into a heap or bin. The heat-loving bacteria within these materials work hard to break down the waste, raising the temperature inside the compost bin.

The materials for hot composting fall into two main categories: ‘green’ and ‘brown’. Green materials are rich in nitrogen and include items such as vegetable peelings, coffee grounds, fresh grass cuttings, and plant trimmings. Brown materials, on the other hand, are carbon-rich and include dry leaves, cardboard, straw, wood chip, and shredded paper. Brown materials also act as bulking agent. The perfect compost has a Carbon-to-Nitrogen ratio of 25-30:1. Our Carbon to Nitrogen Ratio guide explains it in detail.

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Hotbin Hot Composter

Setting up a hot compost bin is straightforward. Choose a compost bin suitable for hot composting, such as a hotbin composter, and place it in a location that allows for good airflow and is easily accessible. Start by adding a layer of coarse brown materials, like twigs or straw, to ensure good air circulation at the base. After this, you can start adding your layers of green and brown materials, carefully maintaining the correct ratio.

The role of temperature in hot composting cannot be overstated. The heat generated within the compost pile is a direct result of the activity of the bacteria breaking down the organic matter to produce compost itself. The optimal temperature range for hot composting is between 43°C (110°F) and 66°C (150°F). These high temperatures accelerate the composting process, kill weed seeds, and destroy pathogens, producing high-quality compost quickly.

It’s important to note that maintaining this temperature range requires the regular turning of the compost pile to introduce fresh oxygen, keeping the compost heap moist but not too wet, and ensuring the compost heap is of a substantial size to retain the heat.

Hot composting is a relatively simple yet highly efficient way of dealing with your garden and kitchen waste, turning it into a valuable resource for your garden. The key to success lies in carefully managing materials and temperature, which we will explore in more depth in the subsequent sections.

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Pros and Cons of Hot Composting

Pros of Hot Composting

  1. Speed: Hot composting is faster than cold composting due to the higher temperatures, which speed up the decomposition process. You can have ready-to-use compost in just a few weeks if you maintain the conditions properly.
  2. Kills Weeds and Pathogens: The heat generated in the composting process is usually sufficient to kill most weed seeds and pathogens, making the resulting compost safer for use in the garden.
  3. Reduces Waste: It’s a practical and eco-friendly way to reduce household waste by transforming kitchen scraps and yard waste into valuable garden compost.
  4. Nutrient-Rich Compost: The resulting compost is rich in nutrients, providing a valuable resource for improving garden soil and promoting plant growth.
  5. Accepts More Types of Waste: Hot composting can handle kitchen scraps that are not suitable for cold composting, such as certain amounts of meat, fish, and even bone. This further helps in waste reduction.

Cons of Hot Composting

  1. Maintenance: Hot composting requires more maintenance than cold composting. You have to regularly turn the compost pile and monitor the moisture and temperature levels to ensure optimal conditions.
  2. Balance of Materials: It requires a good balance of ‘green’ nitrogen-rich material and ‘brown’ carbon-rich material. If this balance is off, it can lead to a smelly pile or slow down the composting process.
  3. Space: Hot composting typically needs more space, as a larger compost pile is better at retaining heat. This might not be suitable for those with small yards or limited outdoor space.
  4. Initial Setup Cost: Starting hot composting might require a certain investment, as you may need to purchase a specific hot composting bin. This could be a barrier for those on a tight budget.
  5. Time and Energy: Setting up and maintaining a hot composting system can be time-consuming and requires a fair amount of physical effort, especially when turning the compost pile.

Best Practices for Hot Composting


Location, Location, Location! The placement of your hot compost bin plays a vital role in the efficiency of the composting process. Although a hot composting bin can be placed on various surfaces, it’s advisable to set it directly on the ground, enabling beneficial organisms from the soil, such as worms and insects, to access the compost material. This enhances the decomposition process and improves the quality of the finished compost. Choose a spot that is easily accessible year-round, so you’re not discouraged from composting during winter months. While the hot compost bin can be located in sun or shade, it’s important to note that excessive sunlight can dry out the compost too quickly, and too much shade can make it too wet. Therefore, a location that offers partial shade throughout the day can strike a good balance.


Rat-proofing your hot composting bin is essential to prevent any unwanted guests. One of the most effective ways to deter rats is to ensure your compost bin is tightly sealed, offering no easy access points. Rats are discouraged by a hot compost bin due to the high temperature, so maintaining a hot composting process is also beneficial. Additionally, avoid adding cooked food waste or meat to your compost, as these items are particularly attractive to pests.

Using your compost

When it comes to using compost produced by a hot or a cold compost bin, it can significantly boost your soil’s fertility, but remember that it’s possible to overuse compost. Spreading a 1-3 inch layer of finished compost on top of your soil can dramatically enhance its nutrient content. However, adding too much can lead to nutrient imbalances that may harm your plants. Compost can also be worked into the soil or used as a mulch.


Worms play an essential role in the composting process. While hot composting primarily relies on thermophilic bacteria to break down the waste, worms aid in further breaking down the material once the compost cools. They also enhance the structure and fertility of the compost, converting organic matter into nutrient-rich worm castings. In the hot composting process, worms naturally find their way into the compost heap once it cools down (it’s cooler towards the bottom), so there’s typically no need to add them manually.

Kick start

A clever method to kick start your hot composting process, particularly in colder months, involves the use of a hot water bottle. By placing a hot water bottle in the centre of your compost pile, you can increase the internal temperature, promoting quicker decomposition. This is especially beneficial at the start of the composting process, as the heat from the water bottle will expedite the initial breakdown of materials, helping to establish the warm conditions necessary for efficient hot composting. Just be sure to safely remove the hot water bottle once your compost pile has self-generated heat. This simple yet effective trick can be the boost your compost needs to get started, particularly in cooler climates or seasons.

Implementing these best practices in your hot composting routine will make the process more efficient and rewarding. Remember that composting is more of an art than a science, so don’t be afraid to experiment to find what works best in your specific situation.

Troubleshooting Common Hot Composting Issues

A well-maintained hot compost pile is typically devoid of any unpleasant odours and will transform your food and garden waste into a rich, fertile organic compost below. However, problems can arise during the hot composting process.

Too Dry

If your hot compost pile is too dry, the decomposition process will slow down because the microbes responsible for the composting process need moisture to survive and function. A pile that is too dry can be rectified by adding green, moist materials such as fresh grass clippings or food waste. Remember, the perfect compost can should have the moisture of a well-wrung-out sponge, damp but not dripping.

Too wet

On the contrary, a compost pile that is too wet can become compacted and smelly, as the excess water can create an anaerobic environment. To rectify a wet pile, add more brown materials such as leaves, cardboard, or shredded paper to absorb the excess moisture. Turning the compost pile can also help to aerate it and facilitate water evaporation.


Seeing maggots in your compost pile can be a shock, but in many cases, they are simply the larvae of compost-friendly flies and will assist in the decomposition process. However, if you find them unsightly or are dealing with a maggot infestation, turning the compost pile more frequently can help, as maggots prefer undisturbed environments. Adding more brown materials can also create a less favourable environment for them.

Too cold

A compost pile that is not heating up is one of the most common issues faced by composters. This is often due to a lack of green materials, which are rich in nitrogen and essential for microbial activity and heat production. It may also be due to a lack of air or moisture, or the size of the compost pile being too small. Turning the pile, adding more green waste, and ensuring the compost pile is at least 3x3x3 feet can help increase the heat.

Bad smell

Lastly, a smelly compost pile is often a sign of an anaerobic environment caused by overwatering, compacted materials, or an imbalance between green and brown materials. Turn the compost pile to introduce air and alleviate the smell. If the pile is too wet, adding brown materials can help restore balance.

Remember, while hot composting is an efficient way to recycle food and garden waste and produce high-quality compost, it requires a balance of the right ingredients and conditions. Regular monitoring and a willingness to adjust based on the compost pile’s needs are the keys to success.

Hot Composting Myths & Misconceptions

Hot composting, though a highly beneficial process, is not without its misconceptions and myths. Let’s debunk some of the most common ones:

Can cooked food go in compost? It is a common belief that you cannot put cooked food in compost. This is true to a certain extent when it comes to cold composting, as it might attract pests and produce odours. However, in hot composting, the high temperatures can break down even cooked food waste, including small amounts of meat and fish, efficiently and without causing any unpleasant smell. Ensure your compost pile achieves a consistently high temperature to make this process safe and efficient.

Can eggshells, banana peels, and onion peels be composted? Another widespread misconception is that certain items, such as eggshells, banana peels, or onion peels, can’t be composted. On the contrary, these items can indeed be composted and provide beneficial nutrients to the compost. Eggshells add calcium, banana peels provide potassium, and onion peels contribute sulphur. However, these items do decompose slowly, so breaking them into smaller pieces can speed up the process.

Do hot compost bins smell? Many people worry about unpleasant odours from compost bins. A properly managed hot compost bin should not smell bad. The key is to maintain the right balance of green and brown materials, turn the pile regularly to encourage aeration and ensure the pile doesn’t become too wet. If your hot compost bin starts to smell, it usually indicates that something in the process needs adjusting.

The impact of composting on waste management Composting is an excellent way to manage household waste, but some individuals believe it doesn’t make a significant difference. This belief is incorrect. Composting not only reduces the amount of waste going to landfill but also recycles it into a nutrient-rich soil conditioner that benefits gardens and landscapes. In fact, composting can divert as much as 30% of household waste away from the garbage bin.

Dispelling these myths can encourage more people to engage in hot composting, helping us all to contribute towards a more sustainable and greener environment.

Frequently Asked Questions

Can a compost pile be too big or too wet?

Yes, a compost pile can be too big or too wet. If a compost pile is too large, it may be difficult to turn, which can impede the composting process as it prevents good airflow, which is essential for the bacteria and other microorganisms doing the work. For an ideal hot compost pile, aim for a space with a size of around 1 cubic metre.

If a compost pile is too wet, it can become anaerobic, which slows down the composting process and produces a bad smell. It’s crucial to strike a balance in the moisture levels in your compost pile – it should feel like a wrung-out sponge, damp but not dripping. If it’s too wet, add more brown materials like shredded paper or dry leaves to soak up the excess moisture.

What should be put in a hot compost bin?

A hot compost bin should be filled with a balanced mix of ‘green’ and ‘brown’ materials. Green materials include food waste like vegetable peels, fruit scraps, coffee grounds, and fresh grass clippings, which provide nitrogen. Brown materials such as dry leaves, straw, wood chips, and shredded paper contribute carbon to the compost. The ideal ratio is about 2:1 ‘green’ to ‘brown’ by volume.

How to handle a hot compost bin in winter?

Hot composting in winter can be challenging due to the cold temperatures. However, it’s not impossible. The key is to insulate your compost pile to retain the heat. Using a well-insulated compost bin like a Hotbin is beneficial. You could also insulate your compost pile with a tarp or old carpet, especially around the sides. Continue to add waste as usual, but turning should be minimised to prevent heat loss.

Can hot compost start a fire?

While it’s true that a compost pile can generate a significant amount of heat, it’s unlikely to start a fire under normal circumstances. However, if a pile is too dry and exposed to additional heat sources, there might be a risk. Regular turning, maintaining appropriate moisture levels, and not placing the pile near flammable materials are simple measures that can help prevent this unlikely event.

How often should a compost bin be watered or turned?

The frequency of watering and turning your compost bin depends on several factors including the weather, the materials in your pile, and its overall condition. As a general rule, your compost pile should be as damp as a wrung-out sponge, so water it if it seems too dry. In terms of turning, a hot compost pile should ideally be turned every few days to promote aeration and speed up the composting process. However, during winter months, you might want to reduce turning to avoid heat loss.


Jonathan Gaze

Content Editor

Hello there! I’m Jonathan Gaze, Content Editor for Harry Rufus.

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