Green Gardening

60-second guide: making compost

Discover how to make garden compost and what to add to the heap in a minute

Save kitchen waste for composting

You can make garden compost in various ways. Ideally, collect a mix of materials and then add them to the bin in 10cm layers (4in) deep, alternating between green and woody. This does require a lot of space. Most gardeners will probably add to the bin as they work in the garden. If this method suits you, try to add equal proportions of green and brown materials.

Add grass cuttings, but in small quantities only

What you can add

Kitchen scraps of uncooked fruit and vegetables, eggshells; tea leaves, soft plant stems, spent flowerheads, dead leaves, woody stems that have been cut or shredded into small pieces to rot down quicker, wood ash, the bedding from pets (not meat eaters), farmyard manure.

What you can't add

Any cooked food, weeds that are in flower or seeding or have large roots attached –the heat might not kill the seeds; any plant material that is diseased – the infection may be recycled back into the soil; grass cuttings from lawn recently treated with a residual weedkiler.

Heap or bin?

A heap ideally needs to be contained to maintain a good temperature, and it should be covered so that it doesn’t get too wet. Sometimes a heap will have un-rotted material at the edges. A bin can be of any design, but should sit on bare soil for drainage and be easy to fill and empty. A sealed bin most ofetn gets too dry. Wooden bins have a limited lifespan as they start to rot with the compost, unless treated with preservative. They are better insulators if totally enclosed, and can be made from recycled materials, such as pallets. A plastic bin is often lighter to handle and cheaper to buy, but not so good at retaining heat.

What to do if...

The compost is too soft and it smells – add more carbon, such as woody prunings, torn-up newspaper or some cardboard, and mix it in.

It looks too dry – it may be too dry for the organisms that are going to do the work, especially in a sealed plastic bin, so add water. Or there could be too much woody material, so add more leafy waste such as grass cuttings and trimmings of soft stems.

It rots down unevenly – the edges of a compost bin or heap don’t always rot down as quickly as the centre. This can be sped up by mixing the heap, or chopping down all material into small pieces before they’re added. You can always just use the material from the centre of the heap and add fresh material to the remainder.

The process seems too slow - the process is sped up in warmer temperatures, so a bin filled in autumn takes longer than one filled in spring. Also, a bin with the correct content will rot down more quickly, so try adjusting the mix.

You don’t have to wait until every last piece of material is broken down to a crumb, as it will continue to break down in the soil until no longer visible.

Feature adapted by Sarah Brocklehurst.

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