How to make compost with a wormery
By Janice Shipp
Article 7 of 10
How to make compost with a wormery
A decent wormery will produce rich compost for improving your soil using just kitchen waste.
Using the power of worms to munch through your kitchen waste, you can avoid using landfill and instead produce great soil improver for mulching or digging into your garden.
Discover our Best Buy wormeries.
What are wormeries?
Wormeries are containers for composting waste (primarily food waste) with worms. They’re usually sold by mail order or online and come with all you need to get started – including the worms.
How wormeries work
The worms used are brandlings (tiger or manure worms) and red worms – not earthworms.
Give them food scraps and shredded paper and cardboard to eat, and they will break it down into tiny pieces that are excreted as nutrient-rich wormcast compost after about two hours.
Happy worms consume up to their own body weight each day and reproduce rapidly, but they’re quite fussy and easy to kill. For success, it’s important to give them only stuff that they find palatable (see below).
As well as compost, wormeries produce a lot of liquid – some waste is around 90% water. This could potentially waterlog the wormery and drown the worms. Some wormeries are free-draining, but most have a sump for the liquid and a tap for drawing it off.
What can I put in wormeries?
Worms will eat most fruit and veg (raw or cooked, preferably chopped), bread, cut flowers, cooked rice and pasta, finely crushed egg shells, tea leaves and teabags (split open), coffee grounds and shredded paper and cardboard (not coloured or glossy).
They don’t mind if the waste is mouldy, but they won’t eat woody stuff and aren’t keen on citrus fruits, pineapple, onions, leeks or anything salty, spicy or vinegary. Omit meat, fish, oil, fat and dairy waste, as this attracts flies and becomes smelly.
Unlike conventional compost bins, you should only put in small amounts at a time (no more than a 5cm-deep layer). Wait until worms are in the top of this waste before adding more.
At their most productive, even our Best Buy wormeries consumed only about a litre of waste per week. In winter, we put in very little, as worms stop eating when temperatures fall below 10°C. They’re hungriest when between 13°C and 23°C – they need a frost-free place in winter and a shady spot in summer.
What to do with wormery compost and liquid
Compost Worms are painfully slow at producing wormcast compost, but it’s a lot more nutrient-rich than that made on conventional compost heaps. Used as a fertiliser, a little can go a long way – especially when given to houseplants and other long-term container plants. Garden Organic, the national charity for researching organic growing methods, recommends replacing the top 2cm of compost with wormcast compost each spring.
To feed plants in the ground, it recommends applying a 2-3cm layer to the soil surface, targeting greedy feeders, such as courgettes, clematis, roses, and fruit trees or bushes.
Liquid Kitchen waste may be 90% water, so wormeries produce a lot more liquid than they do compost. Many people rate this liquid as a plant food, but ours wasn’t very effective at boosting growth, although composition will vary depending on the contents of the wormery.
Are wormeries worth the effort?
A wormery is more of an interesting and challenging hobby than an easy way of producing compost. Unless you keep them indoors, they’re useless in winter.
And we don’t recommend that you keep one inside, even if the manufacturer's instructions tell you it’s possible - all those we tried attracted fruit flies, and some became smelly.