This list is here for the moment when you are standing over the bin holding something, and you are not sure. It applies to compost worms in ordinary home worm bins. It uses five ratings, and every entry on this page is rated the same way.
Two things worth knowing before you read it. First: the question is rarely "will worms eat this?" — they will eat almost anything. The real question is whether it will ruin your bin, your castings, or your afternoon. That is what these ratings answer. Second: the most common mistake is not the wrong food at all. It is too much food, too fast, sitting on the surface. Bury it, and keep plenty of bedding in the bin.
Bedding
The foundation of the bin. Worms eat it too, slowly — but its first job is structure, air and moisture. You cannot have too much.
Feed freely
Safe in normal amounts. Chop it, bury it under bedding.
Feed sparingly
Worms will eat it, but too much sours the bin. Small amounts, buried deep.
Special system only
Worms handle it well — but not in a kitchen bin. A dedicated system.
Never feed
Harms your worms, your castings, or you. No amount is safe.
The whole list, at a glance
Bedding Cardboard · newspaper · plain paper · egg cartons · brown paper · fallen leaves · coffee filters
Feed freely Most fruit · most vegetables · used coffee grounds · loose tea leaves · crushed eggshells · aged horse, cow, rabbit, sheep and goat manure
Feed sparingly Unbrewed coffee grounds · citrus · pineapple · onion · garlic · brassicas · bread · pasta · rice · grains · sugar · nuts · tea bags · grass clippings · rhubarb · egg
Special system only Meat · fish · bones · chicken manure · dog waste · cat waste · human manure
Never feed Anything sprayed · salt · oil · fat · alcohol · vinegar · chilli · dairy · cured meat · medication · glossy paper · treated wood · plastic
Bedding — the foundation
Around half of a healthy bin, by volume, is bedding. It soaks up moisture, keeps air moving, masks smells and buffers everything else you add. If your bin is wet, sour or smelly, the answer is nearly always more of this — not less food.
And make no mistake: the worms eat it too. Cardboard and paper soften as the microbes get to work, and the worms follow them in. That is why a bin can look half-empty a month later. Bedding is slow food as well as habitat — so keep topping it up.
Corrugated cardboardBedding
The best bedding there is. Tear or shred, dampen until it feels like a wrung-out sponge. Take the tape and plastic labels off first.
Newspaper, plain paperBedding
Uncoated only, shredded. Modern colour ink is soy-based and safe — it is the shiny coating that is the problem, not the colour.
Egg cartonsBedding
Plain grey or brown. Tear them up. They create the air pockets worms travel through.
Brown packaging paperBedding
Uncoated only. No tape, no plastic windows.
Fallen leavesBedding
Deciduous and non-glossy, shredded. Keep out gum and eucalyptus, and anything waxy or strongly aromatic.
Paper coffee filtersBedding
Plain paper filters are biodegradable and count as a carbon-rich brown. Drop the whole filter in with the grounds still inside — that is fine. But be clear with yourself: the grounds inside still count toward your coffee ration. Three filters' worth of grounds is still three portions of coffee, and the paper does not cancel it out. Unbleached filters are the safer choice if you have them.
Untreated wood chips, sawdustFeed sparingly
Very slow to break down. A supplement, not a bulk bedding.
Fruit
AppleFeed freely
Cores and peels. Pre-freeze to speed the breakdown.
AvocadoFeed freely
Flesh and skin. The pit takes a very long time — remove it, or accept that it will still be there at harvest.
Banana and banana peelsFeed freely
A firm favourite. High sugar, so bury it or you will get flies.
Berries, grapes, cherriesFeed freely
Strawberries, blueberries, gooseberries. Break down fast. Bury well.
GuavaFeed freely
Excellent worm food.
Melon, watermelon rindFeed freely
A favourite — but very high moisture. Balance with plenty of dry bedding or the bin turns wet.
Pears, peaches, plumsFeed freely
Take out the stones.
TomatoFeed freely
Slightly acidic, fine in moderate amounts. High moisture — adjust the bedding.
Citrus peelFeed sparingly
Citrus fleshFeed sparingly
More acidic than the peel. Occasional, small amounts.
PineappleFeed sparingly
Acidic. Contains bromelain, an enzyme widely said to harm worms in quantity. Flesh only — not the skin.
Mango, papayaFeed sparingly
Acidic. Small amounts.
RhubarbFeed sparingly
Here the experts do not agree, and I would rather say so than pretend. Oxalic acid breaks down readily in a hot heap — but it is water-soluble, and a damp worm bin is a very different environment. Stalks in small amounts. I keep the leaves out and put them on the heap instead.
OlivesFeed sparingly
Fresh, yes. Brined or cured olives from a jar are salted — those belong under Never Feed.
Vegetables and garden scraps
Vegetable peelingsFeed freely
Potato, carrot, courgette and the like. Excellent all-round food. Chop or pre-freeze.
Leafy greensFeed freely
Lettuce, spinach, watercress, salad scraps. Wilted is easier for worms than fresh. High moisture.
Cucumber, courgetteFeed freely
Very high moisture — add extra dry bedding to compensate.
Pumpkin, squashFeed freely
Soft flesh breaks down beautifully. The seeds may sprout — harmless.
Root vegetablesFeed freely
Carrots, beetroot, radishes, sweet potato.
Sweet peppers, green beans, bean sproutsFeed freely
All good.
Broccoli, cauliflower, cabbageFeed sparingly
Brassicas smell strongly as they break down. Small amounts only.
Onion, leekFeed sparingly
Sulphur compounds. Worms move away from concentrated onion, and then it sits and rots. Chopped small, buried.
GarlicFeed sparingly
As above, more so.
Raw potato, potato skinsFeed sparingly
Slow when raw — pre-freeze or cook first. Never green skins: solanine.
Corn cobsFeed sparingly
The kernels go quickly. The cob takes months. Harmless, but do not expect it gone at harvest.
Grass clippingsFeed sparingly
Thin layers only — they heat up badly in volume. Never from a treated lawn.
Soft plant trimmingsFeed sparingly
Chop finely. Never from sprayed plants.
Algae, sea lettuceFeed sparingly
Rinse the salt out thoroughly first.
Hot peppers, chilliNever feed
Capsaicin irritates worms. They will not touch it, so it sits and rots.
Diseased plantsNever feed
The disease persists in the bin. Deal with it elsewhere.
Coffee, tea, grains and starches
Coffee grounds — usedFeed freely
Used, brewed grounds only. Worms love them — but as a minority ingredient. The trouble comes from proportion, not from coffee itself. Grounds carry caffeine, tannins and polyphenols, which are toxic to worms at high loading; they can pull bin pH down; and a thick layer compacts into an airless mat. Your worms will break the caffeine down given time, but only if coffee stays a small part of what they are eating. My rule after twenty-five years: no more than a fifth of what you feed — and always with plenty of bedding. Mix them in — never lay them on in a layer — and add crushed eggshells alongside.
Coffee grounds — fresh / unbrewedFeed sparingly
This is the distinction almost every food list misses. Unbrewed grounds are a different material from used ones. Coffee waste carries caffeine, tannins and polyphenols, and these are what make it toxic to worms in quantity — brewing strips most of them out, so unbrewed grounds arrive at the bin with a far heavier load still in them. A small amount will not kill a bin, but there is no reason to take the chance: if beans are too stale to drink, brew them anyway, pour the coffee away, and feed the grounds.
Loose tea leavesFeed freely
The leaves, yes. The bag is a separate matter.
Tea bagsFeed sparingly
Updated for 2026. Tear the bag open, compost the leaves, bin the bag — unless it is certified plastic-free. Most commercial bags are heat-sealed with polypropylene, and mesh bags are usually bioplastic. Neither breaks down, and worms cannot digest either. Staples are no longer the issue.
Bread, plain crackersFeed sparingly
Ferment fast and pull in flies. Small amounts, buried deep. No salted or heavily processed bread.
Cooked pasta and riceFeed sparingly
The same problem. This is where a great many new bins go wrong — a potful of rice will sour a small bin within days.
Cooked grainsFeed sparingly
Quinoa, barley, oats, amaranth. Small amounts, buried deeply.
Cereal, flour, branFeed sparingly
Unsweetened only. Sugar-coated cereal: keep it out.
Cooked beans, lentilsFeed sparingly
Unsalted. Small amounts.
NutsFeed sparingly
Unsalted only, and slow to break down. Salted nuts belong under Never Feed.
Sugar, cakeFeed sparingly
Small amounts feed the microbes. Larger amounts drive a bacterial bloom, a sour smell and flies. Iced or fatty cake: keep it out.
Tofu, linseed / flaxseedFeed sparingly
Protein-rich and ferments quickly. Small amounts only.
Salted or processed bread and crackersNever feed
The salt is the problem, not the bread.
Eggs, protein, dairy and animal products
EggshellsFeed freely
Rinse, dry, crush as fine as you can — powder is best. A pH buffer and a grit source. Add a pinch every time you feed. Probably the highest-value item on this entire list.
Plain cooked or raw eggFeed sparingly
Small amounts. It will smell if you overdo it. No seasoning, no frying.
Snails and slugsFeed sparingly
Meat, fish, bonesSpecial system only
Dairy — milk, cheese, yoghurtNever feed
In a home bin: pests, strong smells and anaerobic conditions, and quickly.
Bacon, ham, cured meatNever feed
Not simply because it is meat. It is salt, fat and nitrite preservatives all at once — three separate problems in a single scrap.
Cooked meals with sauce or spiceNever feed
Spices, salt, oil and additives together. Keep them out.
Manures
This is the section most worm food lists get wrong, so it is worth being precise. Aged herbivore manure is the finest worm food in existence. Poultry manure is not dangerous — it is unprepared, and preparation fixes it. Pet and human waste is a genuinely different question: not a food problem but a pathogen problem, and no amount of ageing fully solves that.
Aged horse manureFeed freely
Superb, and it usually comes ready-mixed with straw. Must be aged. Read the herbicide warning below
before you collect a single bag.
Full guide to horse manure.
Aged cow manureFeed freely
Excellent. Age it — fresh manure releases ammonia and holds salts, and both are dangerous to worms at very low levels.
Sheep, goat manureFeed freely
Age or pre-compost first.
Chicken, poultry manureSpecial system only
Not harmful — unprepared. Fresh, it is dry, high in salts and off-gasses ammonia, and it will kill your worms. Soak it, drain it, mix with plenty of carbon, age it, then add in thin layers to an open, well-ventilated system. Prepared properly it makes rich compost.
Dog wasteSpecial system only
A dedicated pet-waste system, outdoors, away from water and away from the vegetable garden. Never a food bin, never on food crops — ornamentals only. The risk is roundworm (
Toxocara canis) and hookworm: the eggs survive in soil for years, and the worms will not reliably destroy them. Gloves, and wash your hands afterwards. Nothing for a week after a deworming or flea treatment.
The full method here.
Cat wasteSpecial system only
Cat is not the same as dog — and it is the more serious of the two. Cats are the only animal that sheds
Toxoplasma gondii in its faeces. The oocysts survive in soil for many months, and composting does not reliably kill them. Toxoplasmosis is a real danger to an unborn child and to anyone with a weakened immune system.
If you are pregnant, do not handle this material at all. Separate system, ornamentals only, gloves every time. And keep the
litter out — the urine clumps carry ammonia and salts, and worms are extremely sensitive to both. Faeces only.
The full method here.
Human manureSpecial system only
Manure from a dewormed animalNever feed
The medication passes straight through the animal and then does exactly what it was designed to do.
Never feed — regardless of quantity
Anything sprayed with pesticide or herbicideNever feed
The one that catches people out. Persistent herbicides are designed to survive composting, and they do. They arrive on treated lawn clippings, and in horse manure from hay-fed animals. You cannot see them or smell them, and they will kill your worms and ruin your castings. If you collect manure, ask what the animals were fed.
Salt and salted foodNever feed
Crisps, salted nuts, soy sauce, pickles, brined olives. Salt damages worm skin and wrecks the moisture balance.
Oil, fat, greaseNever feed
Fried food, cooking oil, butter, ghee. Coats the bedding, blocks the air, turns the bin anaerobic.
AlcoholNever feed
Destroys the microbial life the worms actually feed on.
VinegarNever feed
Sharply acidic.
Processed food with preservativesNever feed
It was preserved for the same reason it will not compost.
Medication, vitaminsNever feed
Antibiotics wipe out the bin's microbial ecosystem.
Glossy paper, magazines, receiptsNever feed
Coated paper does not break down. Till receipts are thermal paper — worth keeping out on principle.
Treated or painted wood, MDF, plywoodNever feed
Chemical treatments. No exceptions.
Wood ash, lime in quantityNever feed
A pH crash happens fast and is hard to reverse.
Cat litterNever feed
The litter itself, quite apart from what is in it.
Plastic, rubber, metal, synthetic fibreNever feed
Including plastic tea bags and vacuum-cleaner dust. It will not break down, and it may leach.
The four rules that matter more than the list
- Bury everything. Food left on the surface is what brings the flies and the smell — not the food itself.
- Bedding is not optional. If the bin is wet or sour, the answer is almost always more cardboard.
- Feed variety, not volume. A little of many things beats a lot of one thing.
- When in doubt, leave it out — or add a very small amount, bury it, wait a week, and look. Your nose is the best instrument you own.
If it is not on this list
This list is a work in progress, and it always will be. If you cannot find what you are looking for, write to me and I will gladly add it.
In the meantime, here is the rule that has served me for twenty-five years: add a very small amount, bury it, wait a week, and look. If the worms are in it, it is food. If it is still sitting there untouched, it is not. And if the bin smells, you already have your answer.
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