The short version
Compost is rotted organic matter, and the whole craft is balancing two things: green material for nitrogen, brown material for carbon. Get the ratio roughly right, keep it damp, and let it alone. Most failed heaps are too wet, too green, or both.
What you need
A bin or a heap
Anything that holds a cubic metre and lets air in. Bigger heaps heat up better than small ones.
Greens
Grass clippings, kitchen scraps, young weeds. Wet and nitrogen rich.
Browns
Cardboard, dry leaves, straw, woody prunings. Dry and carbon rich.
How to do it
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Aim for roughly half and half by volume
Rather more brown than green, if anything. A heap that smells sour has too much green and not enough air.
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Layer as you go
Alternate greens and browns rather than tipping a whole bag of grass in at once.
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Keep it as damp as a wrung-out cloth
Too dry and nothing rots. Too wet and it goes anaerobic and smells.
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Turn it if you want it fast
Turning adds air and speeds things up. Left alone it still works, just over a year rather than a season.
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Use it when it is dark, crumbly and smells of earth
You should not be able to identify what went in. Anything still recognisable can go back in the next heap.
When it goes wrong
It smells bad
- Air
- Balance
Too wet, too green, or compacted. Turn it and add browns.
Nothing is happening
- Moisture
- Size
Usually too dry or too small. Water it and add more material.
Rats
- Food waste
Keep cooked food, meat and dairy out of the heap. They are what attract rats, not vegetable peelings.
Frequently asked questions
Can I compost weeds?
Young weeds yes. Perennial roots and anything in seed, no, unless your heap reliably gets hot, and most do not.
How long does it take?
Six months to two years, depending on how much you turn it and how finely chopped the material was.
