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How to make your own compost

Written by
Image of Rebecca Bevan
Rebecca BevanSenior National Consultant – Cultivated Plants, National Trust
Gardeners adding compost to the beds at Nymans, West Sussex
Adding compost to the beds at Nymans, West Sussex | © National Trust Images/Chris Lacey

Learn about the benefits of homemade compost and how to make your own nutrient-packed soil improver at home. Senior National Consultant and gardening author Rebecca Bevan shares some valuable tips and tricks, from building your compost heap to turning the compost as it breaks down.

The benefits of compost

The main reason for making compost is to enrich the soil and increase the amount of water it can hold. In nature this happens naturally when fallen leaves and other organic matter collect on the surface of the ground and gradually decompose into the soil below.

The key benefits from applying compost are:

  • A well fed, healthy soil
  • A thriving habitat of microorganisms, worms and insects
  • Healthy plants with a greater natural resistance to combat pests and fungal diseases
  • No need to spray or add chemicals/artificial fertilisers
  • Effective organic weed control
  • Effective method of water retention, reducing the need to water plants by hand
  • It’s free to make and means you can recycle waste.

What is compost made of?

Compost can be made from any decomposed organic material, such as leaves, food, straw, and waste grass cuttings. The make-up of compost can vary considerably depending on its ingredients. Most gardens cared for by the National Trust make compost from seasonal garden waste.

In the spring and summer months you’ll usually end up with a high nitrogen content, as more green material tends to be available. In autumn and winter months, the compost has more brown material, which is slower to break down but provides a more bulky compost, great for adding structure to the soil.

Close-up of garden fork in the compost heap full of garden and food waste in the garden at Barrington Court, Somerset.
Compost heap in the garden at Barrington Court, Somerset | © National Trust Images/John Millar

Make your own compost heap

Use this method, to make a supply of great compost for use when you need it.

Create your compost area

The size and number of compost heaps you need will depend on the quantity of waste material you’re going to collect and how often you want to turn it. The minimum you need are two: one to fill and the other to turn the compost into and leave to break down. Once it's ready you can use this while you refill the first heap.

Five wooden pallets standing on their edges and tied together is a simple way to make two small bays for your compost. You may need to use fence posts as extra support. You can also use sleepers, posts, or old planks of wood – it’s up to you. Make sure your compost heap is in touch with the soil below, to allow worms to enter and liquid to drain into the soil.

Collecting garden waste

Your garden waste needs to be a mix of green (nitrogen) and brown (carbon). For example, you could mix grass cuttings or weeds with dead twigs and leaves. The finer you chop up the material, the quicker it will decompose.

Close-up of gardening volunteer with gardening gloves in the compost heap at Mottistone Gardens, Isle of Wight.
The compost heap at Mottistone Gardens, Isle of Wight | © National Trust Images/John Millar

Turning your compost

The centre of your compost heap should get quite warm (above 50 degrees Celsius is ideal for killing weeds and seeds – you can use a compost thermometer to check this). Turn your heap at least once to try and ensure everything from the edges gets mixed into the centre and heated up. You can turn it from the full bay into the empty one. A pitch fork or garden fork is perfect for this.

What to do in heavy rain

If heavy rain is forecast, then it's worth covering your heap so it doesn’t get too wet. The ideal consistency of compost is similar to a damp sponge.

How long to leave your compost

Depending on how finely you chop up the ingredients that go in your compost, how hot it gets, how often you turn it and the time of year, compost can take anything from two months to one year to be ready for using. Finished compost should be brown and crumbly and smell nice.

A gardener plants a young tree in the ground while kneeling

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