Composting: What is it and how to start?

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The main objective of composting is to reduce the volume of organic waste. By recycling domestic waste, carbon footprints and greenhouse gases are also reduced, whilst creating a 100% natural fertiliser. In this guide you will find all the tips you need to make the best compost and to learn how to use it correctly.

What is composting?

Composting is the process of fermentation and transformation of organic matter which, thanks to the presence of oxygen, allows for the production of stabilised and topsoil rich fertilising material: compost. It is used often in gardening and agriculture to improve soil quality.

What is compost?Compost is an essential element for soil fertility. Storing waste and allowing it to decompose slowly is returning to the earth what it has given us and at the same time is a positive gesture for the planet.


Waste is a resource which isn’t used. Recycling waste and turning it into compost is a very under-utilised resource. Nevertheless, there are many benefits to composting, including:

  1. A positive environmental impact: giving the earth back part of what was taken from it without chemical fertiliser;
  2. Savings in everyday life: reducing the amount of domestic waste and, therefore, saving rubbish bags and lightening the load of a community by reducing rubbish collections (organic materials are the largest part of a rubbish bag);
  3. A quality product: producing one’s own 100% natural fertiliser.

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Home composting

Home composting tries to take advantage of organic waste generated in the home (food waste such as items that have long gone past their use by date, vegetable garden maintenance and/or individual gardens) to produce compost.

Biodegradable waste from the home becomes a useful resource through compost, as is it more appropriate for its use in the garden by improving soil quality.

Community composting

Community composting is the management of organic biodegradable waste of a group of people (a building, a neighbourhood, a village…).

This initiative also allows the participation in recycling of organic waste to people who cannot opt for domestic composting.

How to start composting?

compost bin

The essential elements to make good compost are: organic waste, a composter or composting bin, and fermenting time.

Organic rubbish

Organic rubbish is made up of waste or leftovers of biological origin. It is biodegradable and can be used as organic fertiliser. The best known way to recycle organic rubbish is through composting.

To turn waste into compost, it is important to know which waste is organic and which isn’t and which should be put into organic rubbish.

How does a composter work?

It is not necessary to live in the countryside to make compost. It is also possible to make compost in the city or even on a window sill in the kitchen for example.

There are different types of composters:

  • Garden composters: organic waste is gathered on the ground of an area protected from the wind and in the shade. This technique can be used if there is the space and time necessary, as, since it is not sheltered from natural dangers or animals, it is a process which can be very irregular.
  • Urban composters: this technique requires the use of a bucket. The advantage is that the composting bucket protects against climate and animals and does not take up much room. Nevertheless, its volume is small (as it is limited to 1000 litres) in relation to the quantity of waste to be composted, it is possible to use several composters however.
  • Vermicomposting or worm composting (for balconies or flats): this technique consists of composting waste in buckets using worms. The worms eat the organic waste and, after a period of digestion, emit a substance called vermicompost. Worm compost bins are, in the simplest terms, composting bins with small holes in them to allow for moisture and ventilation.

Where can you buy a compost bin? The best place to buy a compost bin is in a garden centre or DIY store. All good stockists will be able to provide you with the information you need and help you with your composting needs. They will advise you whether you need a large composting bin or a small composting bin.

How do composting toilets work?

As well as compost bins for food waste there is also the possibility to create compost using human waste. As society becomes more conscious about reversing climate change and improving the environment, the use of compost toilets has been on the rise in the UK. Known as ‘dry toilets’ because they use no water, compost toilets are used to turn human waste into compost and fertiliser.

Compost toilets have been used at one of the world’s largest music festivals, Glastonbury festival, since 2014. In 2019, there were more than 1,000 compost toilets for festival-goers to use.


How to set up a home composter?

You simply need to purchase four untreated wood pallets, put them in a vertical position forming a square and join them with wire. You can solidify them with supports on each end to avoid the pallets moving under the pressure of the fertiliser.

The process of composting

In the process of composting various phases of decomposition can be distinguished, keeping in mind the evolution of the temperature:

  1. The Mesolithic phase: this is the period of acclimatising of micro-organisms to their new environment and the start of the multiplication and colonising of waste;
  2. The thermophilic phase (40ºC): when thermophilic organisms appear and produce the rapid breakdown of the organic matter;
  3. The cooling phase (60ºC): during this phase actinobacteria take over the breakdown of wax, protein and hemicellulose;
  4. The maturity phase: the period of slow fermentation when part of the less biodegradable organic matter breaks down.
  • The steps to follow to make good compost:
  • Blend waste (where necessary) to facilitate composting and the actions of micro-organisms;
  • Ventilating the mix to let the micro-organism’s breath enough for composting to occur (regularly during the first few weeks, then every 1 or 2 months);
  • Mixing waste to inoculate the new waste with micro-organisms and therefore accelerate their breakdown;
  • Control the humidity to avoid compost drying out and allowing waste to decompose adequately;
  • Sift the resulting mixture to recover the waste which has not fully decomposed and which can be reused.

To accelerate the process of decomposing of waste in the topsoil, it is also possible to add a compost activator (chemical or natural, such as nettle, fern or comfrey).

What is hot composting?If you are in a hurry and want to make your own compost before the spring sets in, you may want to try hot composting. It is a process in which microbial activity within the compost pile is optimised, resulting in finished compost in a much shorter period of time. The size of your compost bin is key, as is the make-up of carbon-rich and nitrogen-rich elements. These include straw, shredded paper or cardboard, dry leaves, fruit and vegetable scraps, and ground coffee and tea bags.

Matured compost can be recognised when the waste is no longer recognisable and there are few red worms. Matured compost is odourless, dark and stodgy. This result is usually obtained after about 6 months. Some composters can produce compost at a much faster rate (in a maximum of 4 weeks).

The best time to use compost is the autumn and the spring as this is the time when worms are most active, but it is possible to use it throughout the year. Compost is also ideal for interior plants if you live in an apartment or flat.