One of the questions I get asked most about the HOTBIN is some version of: can I really put that in?
Cooked pasta. Chicken bones. Last night's leftover curry. Fish skin. Dairy. The answer, depending on where your bin is at, is usually yes. But it helps to understand why a HOTBIN can take things a normal bin can't, and when it's safe to add them.
Why a HOTBIN can handle more than a standard compost bin
A normal cold bin sits at roughly the temperature of the air around it. Often 10 to 20°C here in the UK. At that heat things break down slowly, and the bin can't safely cope with cooked food, meat or dairy.
A HOTBIN holds a steady 40 to 60°C inside, thanks to its insulation and the heat the bacteria generate. At that temperature things break down far faster, pathogens are killed, weed seeds die, and fly eggs don't survive. It's the same idea councils use in their big enclosed composting facilities.
The one thing to watch: only add cooked food, meat, fish and bones once the bin is already running above 40°C. On a new bin, stick to raw fruit and veg until it's up to temperature.
The greens and browns framework
Greens (nitrogen-rich, usually wet) generate the heat and feed the bacteria. Vegetable peelings and fruit scraps. Cooked food once above 40°C. Meat, fish and small bones once above 40°C. Fresh grass clippings. Coffee grounds and plastic-free tea bags. Fresh plant trimmings and weeds.
Browns (carbon-rich, usually dry) give energy, structure and moisture control. Shredded paper and cardboard, plain not glossy. Woodchip. Dry shredded leaves. Egg cartons and paper bags. Plain corrugated cardboard torn into pieces.
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The ratio that works: for every caddy of food waste, add about half a caddy of shredded paper, plus a handful of woodchip for every five handfuls of waste. If you're putting in a lot of wet stuff, up the paper and woodchip to match.
Why woodchip matters more than most people realise
Woodchip pieces are knobbly and irregular. Mixed through the bin, they prop open little gaps that let air move around. That's what keeps the whole process breathing, and therefore hot, fast and free of smells.
Leave the woodchip out and wet waste collapses in on itself. The bin compacts. The air runs out. Things turn slow, cold and smelly. Don't reach for sawdust instead, it behaves like sand and clogs the gaps rather than holding them open. A handful every time you feed the bin. It really isn't optional.
What genuinely shouldn't go in a HOTBIN
Large bones and woody material. Small bones break down fine once it's hot. Big dense bones take an age. Thick woody stems are best chipped first.
Liquids. Food waste already holds plenty of moisture. Pouring liquid in just waterlogs everything and tips the bin towards going airless.
Soft dairy. Hard cheese and butter are fine once above 40°C. Milk, yoghurt and cream add too much moisture and tend to smell.
Glossy paper and coated card. They barely absorb moisture and break down slowly.
Ash. It can damage the plastic over time.
Cat and dog waste. Carnivore waste carries pathogen risks and shouldn't go in a home bin. Herbivore manure, though, like chicken, horse or cow, is brilliant and really gets the heat up.
A practical note on cooked food and meat
The question I hear most is: I've always steered clear of cooked food, are you sure it's fine? It is, as long as the bin's at temperature. Here's how I'd ease into it. Get the bin established on raw fruit and veg, grass, and plenty of paper and woodchip. Check the temperature after a week to ten days. Once you're reliably above 40°C, start adding cooked food, mixed in and covered with browns rather than dumped on top. Bring in meat and fish a week or two after that. A bin running at 50°C takes it all in its stride. Just don't rush the transition.
Quick reference: what can go in a HOTBIN?
- Always fine: raw veg and fruit, shredded paper and card, woodchip, coffee grounds.
- Fine once above 40°C: cooked food, meat and fish, small bones, hard cheese and butter, weeds.
- Keep out: large bones, soft dairy, liquids, sawdust, ash, glossy magazines.
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Further reading
Adam
I'm Adam, the founder of Compost Guy. I'm passionate about empowering people to embrace composting! Whether you're a seasoned composter or just starting your journey, I'm here to help.
