Worm Food Rating List
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 · used coffee filters · aged compost
Feed freely Most fruit · most vegetables · loose tea leaves · crushed / ground eggshells · aged horse, cow, rabbit, sheep and goat manure
Feed sparingly (only small amounts) Used coffee grounds (only 1/5th of the food you add) · 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 · human manure
Never feed Anything sprayed · salt · oil · fat · alcohol · vinegar · chili · dairy · cured meat · medication · glossy paper · treated wood · plastic · metal · glass
FREE: Worm Bin Rescue Checklist — 7 mistakes that kill beginner worm farms (and how to fix each one in 5 minutes)
Bedding — the foundation
Around a third to a 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.
And make no mistake: the worms eat it too. Cardboard and paper soften as the microbes get to work, and the worms follow them. 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 cardboard · Bedding
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 paper · Bedding
Uncoated only, shredded. Modern color ink is soy-based and safe — it is the shiny coating that is the problem, not the color. More on cardboard and newspapers as worm bedding.
Egg cartons · Bedding ★★★★
Plain grey or brown. Tear them up. They create the air pockets worms travel through.
Brown packaging paper · Bedding
Uncoated only. No tape, no plastic windows.
Fallen leaves · Bedding ★★★☆
Deciduous and non-glossy, shredded. Keep out gum and eucalyptus, and anything waxy or strongly aromatic. Avoid eucalyptus, walnut and cedar leaves: they are mildly toxic to worms.
Used paper coffee filters · Bedding ★★☆☆
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.
Fully processed, aged compost · Bedding ★★★★
Only compost that is fully processed and aged, and checked for pests before it goes in.
Untreated wood chips, sawdust · Feed sparingly
Very slow to break down. A supplement, not a bulk bedding.
Fruit
Apple · Feed freely
Cores and peels. Pre-freeze to speed the breakdown.
Avocado · Feed freely
Flesh and skin. The pit takes a very long time — remove it, or accept that it will still be there at harvest.
Bananas (peel and flesh) · Feed freely
Soft, they break down fast, and need no preparation. A firm favourite. High sugar, so bury it or you will get flies.
Berries · Feed freely
Strawberries, blueberries, gooseberries. Break down fast. Bury well.
Guava · Feed freely
Excellent worm food.
Mango · Feed freely
Worms love it. Remove the big pit, or it can sprout.
Papaya · Feed freely
Soft flesh, breaks down easily.
Melon, watermelon rind · Feed freely
A favourite — but very high moisture. Balance with plenty of dry bedding or the bin turns wet.
Pears · Feed freely
Take out the stones.
Tomato · Feed freely
Slightly acidic, fine in moderate amounts. High moisture — adjust the bedding.
Citrus peel · Feed sparingly
Acidic. A peel now and then disappears without trouble. A juicing session’s worth of rind will drop the pH and drive worms out of a small bin. More on feeding citrus peels to worms.
Citrus flesh · Feed sparingly
More acidic than the peel. Occasional, small amounts.
Grapes · Feed sparingly
High sugar. A big pile ferments, molds and draws fruit flies, so mix a handful into other food.
Cherries · Feed sparingly
Same caution as grapes: high sugar, so mix a handful into other food rather than adding a pile.
Peaches and plums · Feed sparingly
The flesh is a favorite. Remove the pit, or it can sprout.
Pineapple · Feed sparingly
Acidic. Contains bromelain, an enzyme some said to harm worms in quantity. Flesh only — not the skin.
Rhubarb · Feed 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.
Olives · Feed sparingly
Fresh, yes. Brined or cured olives from a jar are salted — those belong under Never Feed.
Vegetables and garden scraps
Vegetable peelings · Feed freely
Potato, carrot, courgette and the like. Excellent all-round food. Chop or pre-freeze.
Leafy greens · Feed freely
Lettuce, spinach, watercress, salad scraps. Wilted is easier for worms than fresh. High moisture.
Cucumber, courgette · Feed freely
Very high moisture — add extra dry bedding to compensate.
Pumpkin, squash · Feed freely
Soft flesh breaks down beautifully. The seeds may sprout — harmless.
Root vegetables · Feed freely
Carrots, beetroot, radishes, sweet potato.
Sweet peppers, green beans, bean sprouts · Feed freely
All good.
Broccoli, cauliflower, cabbage · Feed sparingly
Brassicas smell strongly as they break down. Small amounts only.
Onion, leek · Feed sparingly
Sulphur compounds. Worms move away from concentrated onion, and then it sits and rots. Chopped small, buried.
Garlic · Feed sparingly
As above, more so.
Raw potato, potato skins · Feed sparingly
Slow when raw — pre-freeze or cook first. Never green skins: solanine.
Corn cobs · Feed sparingly
The kernels go quickly. The cob takes months. Harmless, but do not expect it gone at harvest.
Grass clippings · Feed sparingly
Thin layers only — they heat up badly in volume. Never from a treated lawn.
Soft plant trimmings · Feed sparingly
Chop finely. Never from sprayed plants.
Algae, sea lettuce · Feed sparingly
Rinse the salt out thoroughly first.
Hot peppers, chilli · Never feed
Capsaicin irritates worms. They will not touch it, so it sits and rots.
Diseased plants · Never feed
The disease persists in the bin. Deal with it elsewhere.
Coffee, tea, grains and starches
Coffee grounds — used · Feed sparingly
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 since 1998: 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 / unbrewed · Feed 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 leaves · Feed freely
The leaves, yes. The bag is a separate matter.
Tea bags · Feed 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 crackers · Feed sparingly
Ferment fast and pull in flies. Small amounts, buried deep. No salted or heavily processed bread.
Cooked pasta and rice · Feed 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 grains · Feed sparingly
Quinoa, barley, oats, amaranth. Small amounts, buried deeply.
Cereal, flour, bran · Feed sparingly
Unsweetened only. Sugar-coated cereal: keep it out.
Cooked beans, lentils · Feed sparingly
Unsalted. Small amounts.
Nuts · Feed sparingly
Unsalted only, and slow to break down. Salted nuts belong under Never Feed.
Sugar, cake · Feed 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 / flaxseed · Feed sparingly
Protein-rich and ferments quickly. Small amounts only.
Salted or processed bread and crackers · Never feed
The salt is the problem, not the bread.
Eggs, protein, dairy and animal products
Eggshells · Feed 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 egg · Feed sparingly
Small amounts. It will smell if you overdo it. No seasoning, no frying.
Snails and slugs · Feed sparingly
Good food — unless slug pellets have been used on them. Then never.
Meat, fish, bones · Special system only
The honest answer is not “never” — it is “not in that bin.” See the section below.
Dairy — milk, cheese, yoghurt · Never feed
In a home bin: pests, strong smells and anaerobic conditions, and quickly.
Bacon, ham, cured meat · Never 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 spice · Never 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 manure · Feed freely
Superb, and it usually comes ready-mixed with straw. Must be aged. Read the herbicide warning below before you collect a single bag.
Aged cow manure · Feed freely
Excellent. Age it — fresh manure releases ammonia and holds salts, and both are dangerous to worms at very low levels.
Rabbit manure · Feed freely
Excellent, and conveniently dry. Age it and mix it with carbon.
Sheep, goat manure · Feed freely
Age or pre-compost first.
Chicken, poultry manure · Special 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 waste · Special 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 waste · Special 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.
Human manure · Special system only
A purpose-built system only, and ornamentals only. Check what your local regulations permit before you begin. More on worms and human manure.
Manure from a dewormed animal · Never 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 herbicide · Never 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 food · Never feed
Crisps, salted nuts, soy sauce, pickles, brined olives. Salt damages worm skin and wrecks the moisture balance.
Oil, fat, grease · Never feed
Fried food, cooking oil, butter, ghee. Coats the bedding, blocks the air, turns the bin anaerobic.
Alcohol · Never feed
Destroys the microbial life the worms actually feed on.
Vinegar · Never feed
Sharply acidic.
Processed food with preservatives · Never feed
It was preserved for the same reason it will not compost.
Medication, vitamins · Never feed
Antibiotics wipe out the bin’s microbial ecosystem.
Glossy paper, magazines, receipts · Never feed
Coated paper does not break down. Till receipts are thermal paper — worth keeping out on principle.
Treated or painted wood, MDF, plywood · Never feed
Chemical treatments. No exceptions.
Wood ash, lime in quantity · Never feed
A pH crash happens fast and is hard to reverse.
Cat litter · Never feed
The litter itself, quite apart from what is in it.
Plastic, rubber, metal, synthetic fibre · Never 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 since 1998: 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.
In general worms can cope with nearly all garden- and kitchen waste you might offer them. Some products the compost worms can eat in large quantities and even live in them while others should only be fed in moderation.
Especially acidic foods should be fed with care. If the acidity of your worm bins bedding becomes very high it might force your worms to migrate out of the bin to avoid death.
Avoid the 7 biggest mistakes that can kill your worms
FREE: Worm Bin Rescue Checklist — 7 mistakes that kill beginner worm farms (and how to fix each one in 5 minutes)
Want a daily feeding log & quick reference card at your bin? Check out Stephan’s Easy Worm Farming Planner (US & Metric).
Find out more about worm food here.
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