How to Make Compost at Home in the UK: A Beginner's Guide

Why bother making your own compost?

A compost bin does three useful jobs at once. It turns waste you would otherwise throw away into a genuinely valuable soil improver, it cuts down what goes in your bin and out to landfill, and it saves you money on shop-bought bags. Recycle Now describes it as an inexpensive, natural process that turns kitchen and garden waste into a nutrient-rich food for your garden.

Homemade compost improves soil structure, helps it hold moisture in summer and drain in winter, and feeds the whole web of worms and microbes that keep a garden healthy. Once you have a bin ticking over, it becomes a habit you barely think about: the peelings go in a tub by the sink, the tub goes out to the bin, and the garden slowly gets richer.

What are greens and browns?

Almost everything about composting comes back to balancing two types of material.

Greens are the soft, moist, nitrogen-rich things. In a UK kitchen and garden that means vegetable and fruit peelings, grass clippings, coffee grounds, teabags (paper ones), soft green weeds and old cut flowers. Greens rot fast and get the process going, but on their own they collapse into a wet, smelly sludge.

Browns are the dry, woody, carbon-rich things: cardboard, scrunched-up paper, cereal and egg boxes, toilet roll tubes, dead leaves, straw, woody prunings and wood chip. Browns rot slowly, but they add structure, soak up moisture and create the air spaces a heap needs to breathe.

Greens get it going, browns keep it breathing. You need both.

The RHS suggests roughly a quarter to a half soft green material with the rest chopped woody brown, while Recycle Now and Garden Organic both suggest thinking of it as a rough 50/50 mix by volume. Do not measure it to the gram. The practical version is simple: every time you tip in a load of greens, add a good handful or two of browns to balance it. If your heap ever looks wet and sludgy, it needs more brown.

What can you put in a compost bin, and what should stay out?

Plenty goes in. The trickier part for beginners is knowing what to leave out.

Good to compost: raw vegetable and fruit peelings, tea leaves and paper teabags, coffee grounds, crushed eggshells, grass clippings, soft prunings, dead leaves (a few), annual weeds before they seed, cardboard, paper, straw and old bedding plants.

Leave these out:

• Cooked food, meat, fish and dairy. Recycle Now is clear on this: never compost them in an open bin. They turn smelly as they rot and attract rats. These belong in your council food waste caddy or a sealed hot composter instead.
• Cat and dog faeces, and used cat litter. These can carry pathogens and have no place in a garden compost bin.
• Perennial weed roots and anything gone to seed. Bindweed, couch grass, dandelion roots and seed heads can survive a cool heap and reappear when you spread the compost. Bin them or drown them in a bucket of water first.

Which compost bin should you choose?

There is no single right answer; it depends on your space and how much waste you produce.

• The "dalek" bin. The classic tapered plastic cone with a lid and a hatch at the bottom. Cheap, tidy and perfect for most gardens. Stand it on bare soil so worms and other soil life can get in.
• A wooden bay (or two). Slatted timber bays hold more and let you build bigger heaps. Two side by side let you fill one while the other finishes off. Ideal for larger gardens and allotments.
• A hot bin. An insulated bin that traps the heat of decomposition, breaks material down far faster and, being sealed, can take some cooked scraps. More expensive, but quick.
• A wormery. A stack of trays where composting worms process kitchen waste into rich worm compost and a liquid feed. Brilliant for flats, patios and small yards with little garden waste.

Before you buy, check your local council. Many run subsidised schemes through GetComposting, where bins are sold off cheaply to encourage home composting, so you may pick up a decent bin for far less than full price.

How long does compost take in the UK?

This is where our climate matters. A cool heap, which is what most people run, breaks down slowly at whatever temperature the weather gives it. In practice that means six to twelve months, and sometimes up to two years, before it is ready. Recycle Now puts the typical figure at nine to twelve months, and the RHS notes garden compost can take anywhere from six months to two years.

A hot heap is different. Built all in one go with the right balance and turned regularly, it heats up from the inside as microbes get to work and can be ready in as little as six to eight weeks, as Garden Organic points out. That is a bigger commitment of effort and material, but far quicker.

Two things speed a heap along: turning and moisture. Turning the heap with a fork mixes in air, which the microbes need; the RHS suggests turning several times a year. For moisture, the RHS gives the classic test in its guide to perfect compost: your compost should feel like a wrung-out sponge, damp but not dripping. Too dry and it stalls; too wet and it goes slimy.

1. 1

   Site it on soil

   Stand your bin on bare earth in a reasonably accessible spot so worms can move in and excess water can drain away.

2. 2

   Layer greens and browns

   Add roughly equal amounts of green and brown material, tearing up cardboard and chopping woody bits so they break down faster.

3. 3

   Check the moisture

   Aim for wrung-out-sponge dampness. Add browns if it is wet and sludgy, add water or more greens if it is bone dry.

4. 4

   Turn it now and then

   Every month or two, fork the material over to mix in air. Skip this if you prefer; it will just take longer.

5. 5

   Wait, then harvest

   Lift the bin or open the hatch and take the dark, crumbly compost from the bottom, leaving the unfinished stuff on top to carry on.

Why is my compost slimy, or why is nothing happening?

Two problems cover almost everything that goes wrong, and both are easy to fix.

Slimy, smelly and wet means too much green and too much moisture, with not enough air. Grass clippings tipped in on their own are the usual cause. Mix in plenty of torn cardboard and scrunched paper, give the heap a good turn to get air through it, and it will recover within a week or two.

Dry, dusty and nothing happening is the opposite: too much brown, not enough green, and often too dry. Add greens such as grass clippings or peelings, water it until it feels like that wrung-out sponge, and the process should wake back up.

How do you know when compost is ready?

You will know by look and smell. Finished compost is dark brown, crumbly and gives off a pleasant, earthy woodland smell, like the floor of a forest. Recycle Now describes it as a crumbly, dark material resembling thick, moist soil with a fresh, earthy aroma.

It will not look perfectly uniform. A few twigs, eggshell fragments or bits of stubborn stalk are completely normal; just pick them out or toss them back in the bin for another round. If it still smells sour or you can recognise last month's banana skins, give it more time.

What about leaf mould?

Autumn leaves are best kept as a separate project. Unlike a compost heap, which is broken down mainly by bacteria generating heat, fallen leaves rot slowly and coolly through the action of fungi, so they do their own thing at their own pace. Piling a big load of leaves into your main bin can smother it and slow everything down.

Instead, gather leaves into a simple chicken-wire cage or a few pierced bin bags, dampen them if dry, and leave them be. The RHS notes most leaves take about two years to break down into crumbly leaf mould, though shredding them first (running the mower over them) can bring that down to six to twelve months. The result is a lovely soil conditioner and seed-sowing ingredient, well worth the wait and the near-zero effort.

Where does compost fit with no-dig?

Compost is the engine of a no-dig garden. Rather than digging it in, you spread a layer over the surface each year and let the worms carry it down, which keeps the soil structure intact and smothers weeds at the same time. A steady supply of homemade compost makes the whole approach far more affordable, since a no-dig plot asks for a good few centimetres of the stuff every year.

If you garden on the heavy, sticky soil so much of Britain sits on, this pairing is especially worth it. Our guide to no-dig on heavy British clay walks through how mulching with compost gradually opens up dense clay and turns it into something workable, without ever putting a spade through it.

Start a bin this month, keep the balance roughly right, and by next autumn you will have your first batch of your own dark, crumbly garden gold.