Composting is the part of growing that most people understand in theory and struggle with in practice. Too wet, too dry, too much brown, not enough green, and suddenly you have a pile of something that smells wrong and is not turning into anything useful. Here is how we manage it on a shared site with 47 members contributing material.

Hot composting vs cold composting

Hot composting requires a critical mass of material (at least one cubic metre), the right carbon-to-nitrogen ratio, and regular turning. When it works, it produces finished compost in eight to twelve weeks and kills weed seeds and pathogens. Cold composting is slower (six to eighteen months) but requires almost no management. On our site we run one hot bay and two cold bays. The hot bay is managed by a small rota of members who turn it weekly.

What goes in

Green material (nitrogen-rich): vegetable peelings, fresh plant trimmings, grass clippings, coffee grounds. Brown material (carbon-rich): cardboard, dry leaves, straw, paper bags. The ratio should be roughly two parts brown to one part green by volume. The most common mistake is adding too much green material at once, which produces a wet, smelly pile that is not composting properly. If your pile smells, add more brown.

What does not go in

On a shared site, we are strict about this. No cooked food, no meat, no dairy, no diseased plant material, no roots of perennial weeds (bindweed, couch grass, dock). Diseased material and perennial weed roots go in the council green waste bin, not the compost. We had a bindweed problem in 2020 that we traced back to someone composting the roots, and it took two seasons to clear.

Using the finished compost

Finished compost is dark, crumbly, and smells like earth. It is not a fertiliser in the conventional sense but a soil conditioner that improves structure, water retention, and microbial activity. We spread it on beds in autumn after clearing crops, and again in spring before planting. Members can take a barrow-load per season from the finished bay. Sign the sheet in the shed so we can track usage.

Good compost takes time and attention, but once you have a working system it becomes one of the most satisfying parts of running a plot. Everything that comes off the site goes back into it.