Why Kitchen Scraps Deserve a Place in Your Garden

Every week the average British household sends several kilos of vegetable peelings, tea leaves, coffee grounds and wilted salad leaves to landfill. That is a small tragedy, because those scraps are the raw material for the finest soil improver you will ever lay your hands on. Good homemade compost is dark, crumbly, sweet-smelling stuff that holds moisture like a sponge, feeds the soil life beneath your feet and saves you a fortune in bagged alternatives.

There is a wildlife dividend too. A warm compost heap is a refuge for slow worms, frogs, beetles and the occasional hedgehog, and the insects it breeds feed robins and wrens through the lean weeks of late winter. Do give the heap a gentle prod with a fork before you turn it in earnest, just in case something has taken up residence.

Greens and Browns: Getting the Balance Right

Successful composting comes down to one idea: keep the nitrogen-rich "greens" and the carbon-rich "browns" in balance. Greens are wet and rot quickly; browns are dry, bulky and give the heap structure and air. Aim for roughly two to three parts browns to one part greens by volume, and you will rarely go far wrong.

• Greens: vegetable peelings, fruit scraps, tea leaves, coffee grounds, grass clippings, spent annuals, comfrey leaves, nettle tops, seaweed if you garden near the coast.
• Browns: shredded cardboard and newspaper, egg boxes, loo roll tubes, straw, dry autumn leaves, woodchip, chopped hedge prunings, sawdust from untreated timber.

Learn to read your heap. If it is slimy, sour-smelling and matted, you have too many greens — fork in shredded cardboard and turn it. If it is dry, pale and simply sitting there doing nothing, add kitchen scraps, a little water and a handful of soil or finished compost to introduce the microbes.

What to Add — and What to Leave Out

Most kitchen scraps are fair game, but a few things cause trouble in a domestic heap.

• Add freely: raw fruit and vegetable trimmings, banana skins, apple cores, tea leaves and paper tea bags, coffee grounds and filters, crushed eggshells, stale bread in small quantities.
• Use in moderation: citrus peel, onion skins and potato peelings, which slow the process if added in bulk but are perfectly fine mixed through.
• Leave out: cooked food, meat, fish, bones and dairy, which attract rats and foxes; perennial weed roots such as bindweed, couch grass and dandelion; diseased plant material; cat and dog waste; glossy magazines; and plastic-lined tea bags, which leave a ghostly mesh behind for years.

If you want to compost cooked leftovers, a sealed bokashi bin or a wormery is a far better home for them than an open heap.

Turning, Moisture and Warmth

Aim for the moisture of a wrung-out sponge. Squeeze a handful: a few drops should appear, no more. If water runs freely, add browns and turn; if your hand stays dry, water the heap and add greens.

Turn the heap every two to four weeks with a fork, bringing the outside to the middle and the middle to the edges. This reintroduces air, which is what the aerobic bacteria that do the real work need. A cubic metre is about the ideal size for holding heat; a dalek bin will work well if you add a handful of shredded cardboard with every bucket of scraps, while a pallet bay suits larger gardens and lets you build two heaps so one can mature while the other fills.

In winter, activity slows to a crawl. Insulate the bin with an old carpet, keep the lid on to stop it waterlogging, and be patient. In high summer, check moisture weekly — heaps dry out fast in a heatwave.

Composting Through the British Year

Spring brings the grass-clipping glut. Add them in thin layers, mixed with cardboard or woodchip, or they will mat into a stinking slab. Early summer is the time to turn and water; late summer and autumn deliver the great browns harvest, so bag shredded leaves for leafmould and keep some back for layering. Through winter, carry on adding scraps, cover the heap, and let the worms do their quiet work. A heap started in autumn is usually ready by the following autumn — six to twelve months is typical.

When It's Ready — and How to Use It

Finished compost is dark, crumbly, faintly sweet and unrecognisable as the scraps you tipped in. If it is still lumpy, sieve it and return the lumps to the next heap. Spread it as a mulch around perennials and fruit bushes, dig it into vegetable beds, or mix it with loam and grit for containers. Use it as a top dressing for lawns and a handful in every planting hole. For seed sowing, sieve it finely or use a bought seed mix, as fresh compost can be a little rich for delicate roots.

Feed your soil and it will feed you. Keep the balance right, keep the heap moist, turn it now and then, and by this time next year you will be wondering why you ever threw a carrot peeling away.