How to Compost Kitchen Scraps for Your Garden

Every day a kitchen produces vegetable peels, stems and tea leaves. Instead of throwing them away, you can turn them into compost, a dark, crumbly material that feeds the soil and makes pots and beds grow better.

Think about how much goes into the kitchen dustbin every day: peels, stems, tea leaves, a wilted bunch of coriander. Together they make up a big part of household waste, and the nice thing is that they are exactly what a garden needs.

Composting is easier than most people think. You need a container, a mix of wet and dry waste, a little moisture and some patience. Here is the simple way to do it, including the temperature that helps it work.

At a glance

Mix: about 2-3 parts brown (dry) material to 1 part green (wet) material, by volume
Moisture: like a wrung-out sponge
Hot compost: 130-160°F (54-71°C), ready in 1-3 months
Slow or cold compost: ready in 6-12 months
Turn it every 1-2 weeks

Benefits of composting at home

Compost helps your plants in several ways. It feeds the soil with a slow supply of nutrients, so you need less fertiliser. It loosens heavy, clay-like soil and helps sandy soil hold water, which means less watering. Compost also brings in earthworms and helpful microbes, which makes the soil more alive, and plants grown in living soil are generally stronger.

It helps the environment too. When food waste goes to a landfill it breaks down without air and produces methane, a strong greenhouse gas, but in a compost bin it breaks down with air and turns into something useful. Composting also cuts the amount of rubbish you throw out, and for many families it ends up saving the cost of buying potting soil and plant food.

Composting around the world: weather and season

People have been returning plant waste to the soil for thousands of years. In India, the Indore method, developed by the British agricultural scientist Sir Albert Howard in the 1920s and 1930s in the city of Indore, became one of the best-known composting methods in the world. In Japan, bokashi, a method that ferments kitchen scraps in a sealed bucket, is popular for apartments. In many European countries households have separate bins for food waste, and gardeners everywhere keep a heap or bin at the back of the garden.

Weather decides how fast compost works. In warm and humid places, such as India in summer and the monsoon, microbes are very active and compost can be ready in a couple of months, although you need to cover the bin from heavy rain and keep it from getting soggy. In cool climates the pile slows down in autumn and nearly stops in a hard winter, then speeds up again in spring. A bin in a sunny, sheltered corner works faster than one in deep shade.

What to add: greens and browns

Good compost needs two kinds of waste. Greens give nitrogen and moisture. Browns give carbon and air space.

Greens (wet): vegetable and fruit peels, stems, leftover raw vegetables, tea leaves, coffee grounds, fresh grass clippings and plant trimmings.
Browns (dry): dry leaves, shredded cardboard and paper, sawdust, dry grass, straw, egg cartons and coconut coir.
Eggshells in small amounts, crushed, add calcium.

What to avoid

Cooked food, oil and ghee, dairy, meat, fish and bones. They smell and attract rats and flies.
Diseased plants and weeds with seeds.
Pet waste.
Glossy paper, plastic, tea bags that contain plastic.
Large amounts of onion, garlic and citrus peels at once. They break down slowly, so add them in small quantities.

How to start composting at home

Start small. A bucket on the balcony or a corner of the garden is enough, and you can always scale up when you see how easy it is.

Choose a bin with a lid and holes for air: a compost bin, a bucket with holes drilled in it, a tumbler or a corner of the garden.
Start with a 3-4 inch (8-10 cm) layer of browns at the bottom.
Add your kitchen greens and cover them with browns every time. This keeps smell and flies away.
Keep the mix as damp as a wrung-out sponge. Add water if it is dry or more browns if it is wet and smelly.
Turn or stir the pile every 1-2 weeks with a stick or fork to add air.
Keep a small covered bowl in the kitchen for scraps and empty it into the bin once a day or every two days.

Temperature and weather

Temperature is what turns a pile of scraps into compost, because the microbes that do the work like warmth.

A big, well-mixed pile heats up to 130-160°F (54-71°C) as microbes work. This hot compost is ready in 1-3 months.
In small bins and in cold weather, compost works more slowly. It can take 6-12 months and that is fine.
In winter, keep the bin in a sunny, sheltered place and add more browns for insulation.
In hot, dry weather, keep the bin in partial shade and check moisture often.

How do I know compost is ready?

It is dark brown, crumbly and smells like fresh earth.
You can no longer recognise the original scraps, except maybe small bits of eggshell or twigs.
It no longer feels warm in the middle.

How to use compost

Mix 1 part compost with 3 parts potting soil when filling pots.
Spread a 1/2-1 inch (1-2.5 cm) layer on top of the soil around established plants and water it in.
Don’t use unfinished compost on seedlings, because it can burn tender roots.

Common problems

Bad smell: too wet or too many greens. Add dry browns and turn the pile.
Nothing is happening: too dry or too many browns. Add water and some greens.
Flies or rats: you added cooked food or left scraps uncovered. Bury scraps under browns and keep the lid closed.

Frequently asked questions

Can I compost in an apartment?

Yes. Use a lidded bucket or small bin on the balcony, with plenty of dry browns, or try a bokashi or worm bin.

How long does compost take?

A well-managed hot pile takes 1-3 months. A small, slow bin may take 6-12 months.

Can I add cooked leftovers?

It is better not to. Cooked food and oil attract pests. Stick to raw vegetable and fruit scraps.

Use your compost in your pots. Read our kitchen garden guide for beginners to get started.