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How to compost at home: a beginner's guide

Roughly a third of household waste is peelings, coffee grounds and garden trimmings that could become free soil food. Composting is simply giving microbes the right mix of food, water and air. This guide covers what goes in, which method suits your space, how to set it up and what to do when something goes wrong.

How to compost at home: a beginner's guide
Photo: Andy Li, CC0 · Wikimedia Commons
Basic recipe
About 2–3 parts browns to 1 part greens (estimated)
Moisture
Like a wrung-out sponge
Ready in
2–12 months depending on method (estimated)
Never add
Meat, dairy, oil, diseased plants, pet waste

What is compost and why make it?

Compost is organic matter that bacteria, fungi, worms and other small creatures have broken down into a dark, crumbly, earthy-smelling material. It is not a strong fertilizer, but it is one of the best things you can add to soil.

  • Better soil structure: Loosens heavy clay and helps sandy soil hold water.
  • Slow nutrients: Releases small amounts of nutrients over months and feeds soil life.
  • Less waste: Kitchen and garden scraps stay out of the trash and landfill.
  • Saves money: Less bagged soil improver and mulch to buy.
An open compost heap of garden and kitchen waste.
An open compost heap of garden and kitchen waste. Photo: Ksd5, CC0 · Wikimedia Commons

Greens and browns: the two ingredients

Microbes need two kinds of food. Greens are fresh, moist and rich in nitrogen; they make the heap work fast. Browns are dry, woody and rich in carbon; they provide energy and keep air spaces open. Too many greens make a wet, smelly heap; too many browns make a heap that barely changes. A practical start is roughly 2–3 buckets of browns for every bucket of greens by volume (estimated).

Greens (nitrogen)

  • Fruit and vegetable peelings
  • Coffee grounds and tea leaves (plastic-free bags)
  • Fresh grass clippings, in thin layers
  • Soft green prunings and spent bedding plants
  • Manure from plant-eating animals (rabbits, chickens, horses)

Browns (carbon)

  • Dry fallen leaves
  • Plain cardboard and egg boxes, torn up
  • Shredded paper and newspaper (no glossy paper)
  • Straw, wood chips, small chopped twigs
  • Sawdust from untreated wood, in small amounts

What can and cannot go in

A home heap rarely gets hot enough to kill every pathogen or seed, so some things are better left out. When unsure, leave it out.

Yes

  • Raw fruit and vegetable scraps
  • Crushed eggshells
  • Coffee grounds, filters, loose tea
  • Leaves, grass, plant trimmings
  • Cardboard, paper towels, plain paper
  • Hair and pure wool or cotton scraps
  • Wood ash in small amounts

No

  • Meat, fish and bones
  • Milk, cheese, yogurt and other dairy
  • Cooking oil, fat and greasy food
  • Diseased or pest-infested plants
  • Cat and dog waste, used cat litter
  • Perennial weed roots and weeds with seeds
  • Glossy paper, coated cardboard, coal ash

⚠️ Never add cat or dog waste: it can carry parasites that survive a home heap. Meat, dairy and oil attract rats and cause bad smells.

Choosing a method

Pick a method by space and how much waste you make. All of them use the same green-brown logic.

Open heap in the garden

  • Cheapest; just a corner of bare soil.
  • Best for lots of leaves and garden waste.
  • Slower and looks untidy; can attract animals if scraps are exposed.

Compost bin

  • Closed plastic or wooden bin standing on soil.
  • Tidy, keeps heat and moisture in, deters pests.
  • Good for most gardens; a second bin lets one batch mature while you fill the other.

Sealed bucket / bokashi (balcony)

  • Airtight bucket where food scraps ferment with an inoculated bran.
  • Accepts small amounts of cooked food; little smell when sealed.
  • Not finished compost: the fermented mix must be buried in soil or added to a bin to break down for a few weeks.

Worm composting

  • Bin of tiger or red worms (not earthworms from the garden) in bedding.
  • Works indoors or on a balcony; makes very rich worm castings.
  • Feed small amounts; worms dislike citrus, onion, heat and frost.
Compost worms working through kitchen scraps.
Compost worms working through kitchen scraps. Photo: Gordon Joly, CC BY-SA 4.0 · Wikimedia Commons

Setting up step by step

For a bin or heap in the garden:

  1. Choose the spot: Level, well-drained ground in part shade, easy to reach from the kitchen. Standing the bin on bare soil lets worms and microbes move in.
  2. Start with a coarse base: Lay 4–6 in of twigs or straw at the bottom so air can circulate and excess water drains.
  3. Layer greens and browns: Add kitchen scraps and fresh material, then cover each addition with a thicker layer of browns. Always finish with browns on top to block flies and smells.
  4. Chop large pieces: Cut stalks, peels and cardboard into pieces of about 2 in or smaller; they break down much faster.
  5. Check moisture: Sprinkle dry layers with water; add more browns to wet ones.
  6. Add a handful of soil or old compost: It brings in the microbes that start the process.
  7. Keep feeding and turn: Keep adding in the same way and mix the heap every few weeks.

Moisture, air and turning

Composting microbes need both water and oxygen.

  • Moisture: Squeeze a handful. It should feel like a wrung-out sponge: damp, with a drop or two of water at most. Bone dry means nothing happens; dripping wet means air is pushed out and the heap turns sour.
  • Air: Coarse browns keep air channels open. Avoid thick mats of grass clippings, which compact and turn slimy.
  • Turning: Mixing the heap with a fork every 2–4 weeks (estimated) brings in fresh air and moves outer material to the hot center. No turning still works, just more slowly.
  • Heat: A large, well-balanced heap (about 3 × 3 × 3 ft or more) can warm up noticeably inside. Small bins stay cooler; that is normal.

When is compost ready?

Finished compost is dark brown, crumbly, and smells like forest soil. You should no longer recognize the original scraps, apart from a few twigs or eggshell pieces. The heap will also have shrunk to about half its starting volume.

  • Turned hot heap: about 2–4 months (estimated).
  • Unturned bin: about 6–12 months (estimated).
  • Worm bin: castings can be harvested in about 3–6 months (estimated).

Sieve out coarse pieces and put them back into the bin. Test maturity simply: put compost in a pot and sow a few cress seeds; if they sprout and grow normally, it is ready.

Mature compost: dark, crumbly and with no recognizable scraps.
Mature compost: dark, crumbly and with no recognizable scraps. Photo: Bernard Dejean, CC BY-SA 4.0 · Wikimedia Commons

Using finished compost

  • Garden beds: Spread a 1–3 in layer in spring or fall and work it lightly into the top soil, or leave it as mulch.
  • Potting mix: Mix about 1 part compost with 3–4 parts potting soil (estimated). Pure compost is too dense and rich for pots.
  • Seedlings: Use little or none in seed-starting mix; young seedlings prefer a fine, low-nutrient medium.
  • Lawns and trees: Sieve and spread a thin layer over the lawn, or put a ring of mulch around trees, keeping it away from the trunk.

⚠️ Use only fully mature compost in pots. Half-finished compost can keep decomposing in the pot, warm up and harm roots.

Common problems and fixes

It smells rotten or like ammoniaToo many greens or too wet, so air is missing. Mix in plenty of dry browns (torn cardboard, leaves) and turn the heap.
Fruit flies or other fliesBury fresh scraps in the center and always cover them with a layer of browns. Keep the lid closed; for bokashi, press out air and seal tightly.
Too wet and slimyAdd browns, turn the heap and cover it from heavy rain. Check that the base drains.
Too dry, nothing changingWater while turning until it feels like a wrung-out sponge and add some fresh greens.
Not heating upThe heap may be too small, too dry or short of greens. Add greens and water, turn, and build a bigger batch at once if you want heat. A cool heap still composts, just slowly.
Rats or other animalsLeave out meat, dairy and cooked food, use a closed bin with a wire mesh base and keep the contents moist.

Frequently asked questions

Can I compost citrus and onion peels?

Yes in a garden heap, in moderation. In a worm bin keep them to a minimum because worms dislike them.

Should I add compost starter or activator?

Usually not needed. A handful of garden soil or finished compost brings in enough microbes; a good green-brown balance matters more.

Can I compost in winter?

Yes. Activity slows in cold weather but you can keep adding scraps; the heap speeds up again in spring.

Are 'compostable' bags OK in a home bin?

Many are designed for industrial composting and break down slowly at home. Check the label for home-compost certification, or leave them out.

Can I compost on a balcony without smells?

Yes, with a sealed bokashi bucket or a well-kept worm bin. Smells usually mean too much food or too little dry bedding.

Plants that love compost-rich soil

TomatoZucchiniPepperLettuceBasilRoseStrawberryPumpkin

Sources

Last updated: 2 November 2026