A Small Space Is No Barrier

You do not need an acre, a compost heap the size of a shed, or a long garden with a hedge behind it. A balcony, a paved back yard, a shared courtyard or even a bright corner of a kitchen will do. A sealed bin roughly the size of a wheelie bin can quietly absorb the peelings, tea leaves and coffee grounds of a two- or three-person household, and if you get the balance right it will not smell, will not attract rats, and will hand you back something genuinely lovely within a few months.

The secret is understanding that a compost bin is not a bin at all. It is a habitat. Feed the microbes and the worms properly and they do the work for you, winter included.

Choosing and Siting a Sealed Bin

Sealed bins come in three broad flavours, and the right one depends on how much you have and where you can put it. A conventional lidded compost bin — 100 to 220 litres, often available subsidised through your local council — keeps rain out and pests away and sits happily on soil or paving. A bokashi bin ferments rather than rots, lives under the sink, and will take cooked leftovers that an outdoor bin will not. A wormery suits a small flat beautifully, though it is fussier about temperature and moisture.

• Capacity: 100 litres is ample for a couple; go to 200 for a family of four.
• Site: level, well-drained and out of the fiercest midday sun. Put it near a door — a bin you have to walk to the end of the garden to use is a bin you stop using by February.
• Base: if you can stand it directly on soil, do. On paving, start with a 10cm layer of coarse twigs or broken-up cardboard to give drainage and airflow.
• Two bins: the single best upgrade. One filling, one maturing, so you are never waiting on a full load to finish.

Greens and Browns: The Only Ratio That Matters

Everything you add is either a green or a brown, and the whole craft lies in mixing them.

Greens are wet and nitrogen-rich: vegetable and fruit peelings, tea leaves, coffee grounds, grass clippings, spent flowers, bolted lettuces, annual weeds before they set seed. Browns are dry and carbon-rich: torn cardboard, egg boxes, loo-roll tubes, newspaper, autumn leaves, straw, untreated sawdust, woodchip, shredded paper.

Aim for roughly two parts browns to one part greens by volume. One bucket of potato peelings therefore wants two buckets of scrunched-up cardboard. The browns are what keep the pile open, soak up excess moisture and stop the whole thing turning slimy and sour. If it whiffs, add browns. If it looks dusty and nothing is happening, add greens or a splash of water. A thin layer of browns on top every time you tip in the day's peelings also keeps fruit flies at bay.

What to Feed It — and What to Keep Out

• Yes please: peelings, tea leaves (split the bags — many UK tea bags still contain a plastic mesh that will not break down), coffee grounds and paper filters, crushed eggshells, dead houseplants, hair and nail clippings, dustpan sweepings, stale herbs.
• Leave out of an outdoor bin: cooked food, meat, fish, dairy and anything oily, which attract rats and foxes; dog and cat waste; treated or painted wood; glossy magazines; diseased plant material such as potato blight haulm or rose blackspot leaves.
• Never: perennial weed roots like bindweed, couch grass or ground elder, which will happily regrow in your beds once you spread the compost; and anything that has been in contact with weedkiller.
• In moderation: citrus peel, onion skins and bread are fine in small amounts, but large quantities slow the process down.

If you are working indoors, a bokashi bin takes up the slack — cooked scraps, a little meat and fish, cheese rinds — fermenting them in a fortnight before you bury the results or add them to the outdoor bin.

Turning, Moisture and Warmth

Turn your bin every fortnight or so, using a compost auger or simply an old broom handle plunged in and stirred. Turning introduces air, which is what the aerobic microbes need, and it lets you spot trouble early. Aim for the texture of a wrung-out sponge: damp enough to glisten, never dripping. A lid keeps the worst of the rain off, but after a wet British October you may need to add extra cardboard regardless.

From November to March, when temperatures sit below about 5°C, everything goes quiet. That is normal. Insulate the bin with a sack of leaves or a wrap of bubble wrap, keep feeding it, and accept a slower pace. Come April, a handful of nettle tops or comfrey leaves — old-fashioned activators, both free from the hedgerow — will get it churning again. A scoop of finished compost or garden soil now and then introduces fresh microbes and speeds everything up.

From Bin to Border

Your compost is ready when it is dark, crumbly, cool, and smells of a woodland floor after rain. In a sealed bin this usually takes three to nine months, depending on the season. Sieve out the chunky bits and return them to the next bin. Spread the rest as a mulch around raspberries and currants, fork it into a runner bean trench, top-dress containers, or mix it with leafmould for potting.

The first time you lift that lid and smell earth rather than rubbish, you will understand why so many of us end up oddly fond of our bins. Start small, keep the balance, and let the worms get on with it.