Browns (Carbon Materials)
Material
Browns are the dry, carbon-rich ingredients that give a compost heap structure. They create air spaces, absorb surplus moisture and balance nitrogen-rich greens. Common British garden browns include dead leaves, shredded cardboard, torn paper, straw and chopped woody prunings. Keeping a dry stockpile makes composting far easier throughout the year.
How it works
Microbes use carbon-rich material as an energy source while they break down the whole mixture. Coarse browns prevent a heap becoming a wet, airless mass, which is a common cause of smells. Shred or tear cardboard and paper, chop twigs, and mix them through rather than making thick separate layers. Browns decompose more slowly than greens, so they are often still visible when compost is otherwise usable. Roughly half browns and half greens by volume is a helpful starting point, with extra browns useful for very wet grass clippings or kitchen scraps.
Details
Suitable browns include autumn leaves, plain corrugated cardboard with tape removed, uncoated paper, straw, dry plant stems, sawdust from untreated wood in small amounts and woody prunings chipped or chopped finely. Avoid glossy printed card, treated timber, plastic-coated packaging and large amounts of ash. Store leaves under cover and keep cardboard dry beside the compost bin. Woody material can be slow in a cold bin, so use it sparingly or make a separate pile. Hay may be useful only when its source is known, as some hay can carry aminopyralid weedkiller residues.
Tips
Add a generous handful of shredded brown material whenever you add a caddy of kitchen scraps. If grass clippings arrive in quantity, mix them thoroughly with at least an equal volume of dry browns. Keep a lidded container of torn cardboard near the kitchen, so balancing the heap becomes an easy routine.
Browns (Carbon Materials): frequently asked questions
How does browns (carbon materials) work?
Microbes use carbon-rich material as an energy source while they break down the whole mixture.
What do I need to know about browns (carbon materials)?
Suitable browns include autumn leaves, plain corrugated cardboard with tape removed, uncoated paper, straw, dry plant stems, sawdust from untreated wood in small amounts and woody prunings chipped or chopped finely.
What are some tips for browns (carbon materials)?
Add a generous handful of shredded brown material whenever you add a caddy of kitchen scraps.
General guidance for UK gardens and allotments. Page updated 19 Sep 2026.