Making your own compost

Compost is decomposed organic waste. You can buy it, but making it is cheaper, better for the planet, and gives you control over what goes into your soil. A compost heap is a managed rot — you provide the right balance of materials, air and moisture, and bacteria and fungi do the work. The process generates heat (up to 60°C in a well-made heap), which kills weed seeds and speeds breakdown.

The ratio that matters is carbon to nitrogen, roughly 30:1 by weight. Carbon-rich 'browns' — cardboard, paper, woody prunings, straw — give structure and feed the fungi. Nitrogen-rich 'greens' — vegetable peelings, grass clippings, nettles, coffee grounds — feed the bacteria that heat the heap. Too much green and the heap smells of ammonia; too much brown and nothing happens. Aim for two-thirds brown, one-third green by volume, and you will be close.

A hot heap needs turning every two to three weeks to reintroduce air. Each turn restarts the process. A cold heap — no turning, just slow layering — takes nine to twelve months but requires no effort beyond loading it. Both produce good compost. Hot is faster; cold is easier. In a small garden, a 300-litre bin is enough to process the waste from a household and a 10 m × 10 m plot.