A Beginner's Guide to Composting Kitchen Waste

Why Kitchen Scraps Are Worth Their Weight in Gold

If you have ever watched a bin bag of vegetable peelings go out to the wheelie bin, you have watched free compost walking out of your garden. Potato skins, tea leaves, apple cores and the tops and tails of carrots are not rubbish — they are the raw material for the finest soil improver you can get, and your garden will thank you for every handful.

Composting at home saves you money on bagged compost, cuts the weight of your general waste and feeds the soil life that keeps plants healthy. Best of all, it is not complicated. Once you understand the simple rhythm of greens, browns, air and moisture, you can turn a week's worth of kitchen scraps into dark, crumbly compost that smells like a woodland floor.

The Two Ingredients: Greens and Browns

Everything that goes into a compost heap falls into one of two camps. Greens are soft, wet and nitrogen-rich — they get the heap heating up. Browns are dry, fibrous and carbon-rich — they add structure and soak up excess moisture.

• Greens from the kitchen: fruit and vegetable peelings, apple cores, banana skins, salad leaves, tea bags (check they are plastic-free), coffee grounds and filters, crushed eggshells, stale herbs.
• Browns from the kitchen: torn cardboard, egg boxes, loo roll tubes, scrunched newspaper, paper bags, used kitchen roll.
• Greens from the garden: grass clippings, annual weeds before they seed, spent flowers, soft prunings.
• Browns from the garden: autumn leaves, straw, shredded twigs, wood chip, dried stems, hedge trimmings.

Keep meat, fish, dairy, cooked food, oils and pet waste out of an open heap. They smell, they attract rats, and they are best dealt with in a sealed food-waste digester or by your council's collection service.

Getting the Balance Right

The classic rule of thumb is roughly two to three parts browns to one part greens by volume. Kitchen scraps are almost all greens, so for every caddy of peelings, add at least two caddies of torn cardboard or a couple of good handfuls of shredded paper. This is the single most common mistake beginners make: a heap of nothing but vegetable peelings turns into a slimy, sour, fly-ridden mess within a fortnight.

Layer as you go. A few centimetres of scraps, then a scattering of browns, then a sprinkle of soil or old compost to introduce the microorganisms that do the work. Repeat until the bin is full. If you keep a small lidded caddy in the kitchen and a stack of flattened cardboard beside the bin outside, the habit becomes second nature within a week.

Choosing and Siting Your Bin

For a typical UK garden, a dalek-style plastic bin is the easiest starting point, though a wooden slatted bay or a homemade pallet bin works beautifully if you have the space. Whichever you choose, the principles are the same.

• Site it on bare soil, not paving, so worms and soil microbes can move in freely.
• Choose a spot that gets some sun — warmth speeds up decomposition — but not so exposed that it dries out.
• One bin is fine to begin with. Two is better: you can fill one while the other matures.
• Keep a lid on it to stop it becoming waterlogged, but let air in. Anaerobic, airless heaps stink.

Turning, Moisture and Troubleshooting

Aim for the consistency of a wrung-out sponge. Squeeze a handful: if water drips out, it is too wet; if it feels dusty and dry, it is too dry. Add browns to a soggy heap, water it lightly if it is parched, and give it a turn.

Turning is the gardener's secret weapon. Once a fortnight, fork the outside of the heap into the middle and the middle to the outside. This adds oxygen, mixes the ingredients and gets the centre cooking. A well-built heap can reach 50–60°C within days — warm enough to speed things up and kill off many weed seeds and pests.

If something is going wrong, the fix is nearly always simple:

• Slimy and smelly: too many greens and not enough air. Add browns and turn.
• Dry and doing nothing: too many browns. Add kitchen scraps and a splash of water.
• Clouds of tiny flies: bury scraps under a layer of browns rather than leaving them exposed.
• Rats or foxes visiting: remove cooked food and dairy, keep the lid secure and avoid adding fish scraps.

When Is It Ready, and How Do You Use It?

Depending on the season and how often you turn it, a cold heap takes six to twelve months; a hot, regularly turned heap can be ready in as little as three. You will know it is done when it is dark, crumbly, sweet-smelling and you can no longer recognise what went in — though the odd eggshell or avocado stone is nothing to worry about.

Use your finished compost as a mulch around shrubs and perennials, dig it into vegetable beds, or sieve it and mix it with grit and loam for potting. A thin layer spread over the lawn in autumn works wonders, and a scoop in the planting hole gives new plants a flying start. Start small, keep the balance in mind, and within a year you will wonder why you ever threw those peelings away.