How to Start a Compost Bin for a More Sustainable Home

What composting does

Composting is the controlled rotting of plant material by bacteria, fungi and small creatures such as worms and woodlice. With the right conditions, scraps and garden trimmings turn into a dark, crumbly, earthy-smelling material that can be mixed into soil or used as a mulch.

It has environmental benefits, but they are worth stating carefully. Composting at home keeps some organic waste out of the bin, which can reduce waste collection and the methane that food rotting in landfill can produce. It also returns organic matter to soil. However, composting is not a way to make waste disappear, and preventing food waste in the first place is better than composting it. Home compost heaps also release some gases themselves, particularly if they become waterlogged and airless.

Choose a bin and a spot

Many councils and suppliers sell compost bins, often made of recycled plastic, and some areas offer them at a reduced price. You can also build one from wooden pallets or buy a tumbler. All of these work if they hold in warmth and moisture while allowing air in.

Some points to consider:

• Location. A level, well-drained spot in partial shade is usually best. Placing the bin directly on soil, not paving, lets worms and other organisms move up into the pile and lets excess liquid drain.
• Size. Small bins can work for a household with a small garden, but a very small pile may not heat up much. Larger piles retain warmth better.
• Access. Put it somewhere you will actually visit in the rain, not at the bottom of the garden where you will avoid it.
• Neighbours. Keep it away from windows and seating areas, and check any rules in your tenancy or local area.

If you do not have a garden, there are options such as a wormery, a sealed bokashi system or a local food scraps collection. Each has different rules, so follow the supplier’s instructions.

Understand greens and browns

Good compost needs a mix of two kinds of material:

• Greens are moist and nitrogen-rich: vegetable and fruit scraps, tea bags (check they are plastic-free), coffee grounds, fresh grass clippings and plant trimmings.
• Browns are drier and carbon-rich: cardboard, scrunched paper, dry leaves, straw, woody prunings and egg boxes.

There is no single perfect ratio, but a common rule of thumb is to add roughly equal volumes of each, or slightly more browns if the pile looks wet or smells. Greens alone tend to turn into a wet, smelly sludge. Browns alone rot very slowly.

Step by step

1. Set up the base. Start with a layer of coarse material such as twigs or prunings to help air and drainage.
2. Add materials in layers or mix as you go. Chop or tear larger pieces, since smaller bits break down faster.
3. Keep it moist but not soggy. The contents should feel like a wrung-out sponge. Add dry browns if too wet, and a little water if too dry.
4. Cover food scraps. Bury kitchen waste under a layer of browns or existing compost to deter flies.
5. Add air. Turn the pile with a fork every few weeks, or poke holes in it, to introduce oxygen. A tumbler makes this easier.
6. Cover the top. A lid or old piece of carpet keeps rain out and warmth in.
7. Wait. Depending on temperature, mix and turning, compost can take a few months to a year or more. It is ready when it is dark, crumbly and has no recognisable scraps, apart from the odd woody piece.

What to add and what to avoid

Generally fine for a home bin:

• raw fruit and vegetable peelings and scraps
• tea leaves, coffee grounds and filter papers
• crushed eggshells
• grass clippings in thin layers
• leaves, straw, hedge trimmings and soft prunings
• plain cardboard and paper, torn up

Best avoided in a typical home bin:

• meat, fish, bones and dairy, which can attract rats and foxes and smell badly
• cooked food and greasy leftovers, for the same reason
• cat and dog waste, and used cat litter, which can carry pathogens
• diseased plants or persistent weeds with seeds or roots, unless your pile gets very hot
• glossy or heavily printed paper, and anything with plastic coatings
• coal or barbecue ash, and treated or painted wood

Labels such as “biodegradable” and “compostable” can be misleading. Many compostable packaging items need the high temperatures of industrial facilities and will not break down properly in a garden bin, so check the label and your local rules.

Troubleshooting

It smells bad. Usually the pile is too wet or lacks air. Mix in dry browns such as cardboard or leaves, turn it, and cover fresh food scraps. A sour or ammonia-like smell often suggests too many greens.

It is not breaking down. It may be too dry, too cold, or short on greens. Moisten it, add some nitrogen-rich material, chop things smaller and turn it. In cold weather, activity slows naturally.

Flies. Small fruit flies are common in summer. Bury kitchen scraps under browns and keep the lid on.

Rats or mice. Avoid cooked food, meat and dairy. A closed bin on a base of fine mesh can make access more difficult. If rodents are a persistent problem, contact your local council or a pest professional. Handling rodent-affected material calls for gloves and good hygiene.

Ants. These often indicate the pile is too dry. Add water and mix.

Slimy layer of grass. Thick layers of fresh clippings compact. Mix them with browns instead.

Using the finished compost

Home compost is usually less uniform than bought products. Use it as a mulch on borders, dig it into beds, or mix it with other materials for pots. For seed sowing, it can be too rich, and many gardeners prefer a bought peat-free compost for that purpose. Wear gloves and wash your hands after handling it, as it can contain bacteria and fungal spores.

Composting is one of the easier habits to add to an interest in zero-waste living, and it fits naturally with growing plants, whether in a beginner home garden or in pots. It is a useful part of wider waste management at home rather than a complete solution, and it works best alongside buying and cooking only what you will eat.