Greens (Nitrogen Materials)
Material
Greens are the moist, nitrogen-rich materials that fuel rapid composting. Despite the name, they include more than green plant matter: vegetable peelings, coffee grounds and spent flowers all count. Used with enough browns, greens help a heap warm up and turn into rich garden compost without becoming slimy or smelly.
How it works
Nitrogen feeds the microbes responsible for decomposition, so fresh greens are the active part of a compost mix. Grass clippings, vegetable scraps, fruit waste, coffee grounds, young weeds before seeding and spent plants all break down readily. Their moisture can exclude air when piled thickly, particularly with grass, so combine them with dry, bulky browns as you add them. A useful starting point is roughly equal volumes of greens and browns, then adjust by observation. A wet, compact heap needs more browns; a dry, inactive heap needs water and greens.
Details
Collect vegetable peelings and fruit scraps in a kitchen caddy, emptying it regularly into the compost bin and covering each addition with cardboard or leaves. Add lawn clippings in thin mixed layers rather than in a dense lump. Avoid perennial weeds with persistent roots and any weeds carrying mature seed unless you can manage a reliably hot heap. Keep meat, fish, dairy, cooked food and dog or cat waste out of a home heap because they attract vermin; some council garden-waste collections accept different materials. Treat manure, hay and grass from unknown sources cautiously because aminopyralid residues can persist.
Tips
Coffee grounds are a green, even though they are brown in colour, and paper filters can be included as browns. If using manure, know its source and avoid compost from affected material near tomatoes, beans and potatoes. Mix very wet fruit scraps with shredded cardboard immediately to keep flies and odours under control.
Greens (Nitrogen Materials): frequently asked questions
How does greens (nitrogen materials) work?
Nitrogen feeds the microbes responsible for decomposition, so fresh greens are the active part of a compost mix.
What do I need to know about greens (nitrogen materials)?
Collect vegetable peelings and fruit scraps in a kitchen caddy, emptying it regularly into the compost bin and covering each addition with cardboard or leaves.
What are some tips for greens (nitrogen materials)?
Coffee grounds are a green, even though they are brown in colour, and paper filters can be included as browns.
General guidance for UK gardens and allotments. Page updated 19 Sep 2026.