The three side by side
| Compost bin | Worm farm | Bokashi bucket | |
|---|---|---|---|
| Space | A spot in the garden, on soil | A small, shaded spot outdoors or on a balcony | The kitchen bench or a cupboard |
| Takes | Fruit and vegetable scraps plus garden waste; no meat | Fruit and vegetable scraps, paper; little or no citrus and onion; no meat or dairy | All food scraps, including meat and dairy |
| Your job | Add "browns" with every load of scraps; turn it every few weeks | Feed a little at a time; keep it moist and shaded | Sprinkle bokashi bran on each layer; drain the liquid |
| Gives back | Compost to dig in or spread | Worm castings and a liquid to dilute 10:1 | Fermented scraps to bury or compost, and a liquid |
| Watch out for | Smells if too wet or too green; rats if meat goes in | Heat: a box in full sun gets too hot for worms | Needs somewhere to put the fermented scraps |
The lists of what goes in follow Environment Victoria's composting fact sheet and Iowa State University Extension's guide to worm composting. Iowa State lists onion, garlic, peppers, citrus, meat, fish, cheese, oils and salty food as things to keep out of a worm bin.
Sizing a worm farm
Iowa State University Extension gives the rule of thumb: compost worms eat about half their body weight in food a day. A pound of worms, about 450 g, eats up to half a pound of scraps a day. That makes sizing simple:
| Scraps per week | Per day | Worms needed |
|---|---|---|
| 1 kg | about 140 g | 0.3 kg |
| 2 kg | about 290 g | 0.6 kg |
| 3.5 kg | 500 g | 1 kg |
Weigh your scraps for a week before you buy, because households vary enormously. Start with fewer worms than the table if the farm is new. The population grows to match the food, and overfeeding a new farm is the most common way to make it smell. Environment Victoria's advice is simple: if uneaten food is building up, feed less.
Use compost worms, sold as red wigglers or tiger worms (Eisenia fetida and related species), not garden earthworms. Iowa State's standard home bin is about 60 × 90 cm and 30 cm deep, with moist bedding of shredded paper, cardboard or leaves that feels like a wet sponge. The castings are ready to harvest after several months. Environment Victoria notes that in a stacking tray farm, a tray fills every couple of months.
Keeping worms alive in an Australian summer
Worms do best in the mild range. Iowa State gives 65–70 °F, about 18–21 °C, as ideal, within a range of about 13–25 °C. A black plastic farm in the afternoon sun goes well beyond that. Environment Victoria's tips:
- Keep the farm in shade all summer.
- On a very hot day, put a frozen bottle of water in the farm with the lid slightly open, or lay a wet hessian sack or old carpet over the top.
- Where it drops below zero, move the farm into a shed for winter, or cover it with carpet or polystyrene.
Worm farms can also take cat and dog droppings, but keep a separate farm for them. Don't use those castings on food plants, and don't add droppings after the pet has had worming medicine, because it kills the worms.
Sizing a compost bin
A compost heap only heats up if it is big enough to hold its own warmth. Cornell Cooperative Extension's home composting guide says the ideal is about a cubic yard, a heap roughly 0.9 × 0.9 × 0.9 m. A heap that is working heats up to 140–160 °F, about 60–70 °C, and smaller piles take much longer to compost. Most plastic household bins hold well under that volume, so expect them to compost slowly and cool.
The mix matters more than the bin. Every load of scraps and lawn clippings, the "greens", needs "browns" such as dry leaves, shredded paper or straw. A heap that is slimy and smelly has too much green. The compost ratio calculator balances the two by the bucket, to the 25–30:1 carbon-to-nitrogen ratio that composts fastest. When it is done, the compost calculator works out how much to dig in.
How bokashi works
Bokashi is a sealed bucket with a tap at the bottom. Each time you add scraps, you sprinkle over a handful of bokashi mix, usually bran that has been fermented with beneficial microbes. The scraps ferment rather than rot, so there is little smell and it can live in the kitchen. Environment Victoria's advice:
- Drain the liquid through the tap as often as possible. It can be diluted for the garden or poured down the drain to freshen it.
- Two buckets work best: one ferments while you fill the other.
- The fermented scraps are not compost yet. Bury them in the garden, or add them to a compost heap or a friend's, or a community garden's.
That last step decides whether bokashi suits you. It is ideal for an apartment with a friendly gardener nearby, and pairs well with a compost bin: bokashi handles the meat and dairy, the bin does the rest.
Check your council first
Environment Victoria points out that councils often subsidise compost bins and worm farms, which makes the council the cheapest place to buy one. Brisbane City Council, for example, offers a rebate of up to $100 on eligible composting and worm-farming equipment. Search your council's website for "compost rebate" before buying.
Questions
Is a worm farm or a compost bin better?
A compost bin if you have a garden, because it takes prunings, leaves and clippings as well as food scraps. A worm farm if you have little space and mostly fruit and vegetable scraps. Many gardeners run both, with the worm farm for kitchen scraps and the bin for the garden.
How many worms do I need for a worm farm?
Worms eat about half their body weight a day, according to Iowa State University Extension, so divide your weekly scraps by 7, then by 0.5. Two kilograms of scraps a week needs about 0.6 kg of worms. A new farm can start smaller and grow.
Can worms eat citrus and onion?
Only a little, if any. Iowa State lists onion, garlic, peppers and citrus among the foods to keep out of a worm bin, along with meat, fish, cheese, oils and salty food. Put those in the compost bin or a bokashi bucket instead.
Can you put meat in a bokashi bin?
Yes. Bokashi takes meat and dairy scraps, which compost bins and worm farms should not. The fermented contents still need burying in the garden or adding to a compost heap.
Sources
- Environment Victoria, The quick guide to composting, worm farms and bokashi – which system suits which home, what each takes, care, worm farm heat and frost, pet droppings, bokashi, council subsidies.
- Iowa State University Extension and Outreach, How to create and use vermicompost – worm species, feeding rate, bin size, bedding, temperatures, foods to avoid, harvest time.
- Cornell Cooperative Extension, Home composting: a guide to small scale food and yard waste composting – a one cubic yard pile, 140–160 °F working temperatures.
- Brisbane City Council, Bokashi and other food waste recycling methods – rebate for composting and worm-farming equipment.
- Carbon-to-nitrogen targets as on the GardenMaths compost ratio calculator.
Last reviewed 24 September 2026 · Report an error