January 20, 2019
How does a wormery work?
A wormery is a container in which composting worms live, that is managed for converting organic (usually “waste”) material such as fruit and veg scraps, garden greens, or animal manure into valuable compost.
Worms can eat up to half of their own body weight each day, and their population increases rapidly under favourable conditions, so a wormery can be a very effective asset in many waste management and gardening applications.
Wormeries can follow many different designs, as long as they allow for maintenance of healthy conditions for the worms and easy accessibility for both feeding and harvesting of compost. They can be made from an old bath or fridge or freezer, from stacked car tyres, from plastic boxes, or in a container made from wood or from concrete blocks. There are even fabric wormeries available, and in fact these are very effective.
The main considerations are that a wormery should have a lid that protects it from the elements and from pests, there should be good drainage, and if possible a good degree of ventilation.
The worms used for composting are “surface dwelling” or “epigeic”, and they have a different life to the larger “soil dwelling” earthworms that we find when digging in our gardens. Surface dwelling worms are naturally found in piles of animal manure, in compost heaps, or in other above-ground organic matter. The fact that they live above ground is what makes them suitable for life in a wormery, when they are never in contact with soil.
A wormery can be kept indoors or outdoors, but ideally in a shady spot as the heat and drying effect of the sun can be very injurious to the worms. The wormery should be started off by adding moist bedding for the worms to live in. The bedding can be wetted paper, cardboard, straw, hay, sawdust, compost, well-rotted manure, brown leaves, coir, or any combination of these sorts of materials. The worms are added, and then food such as fruit and veg waste can be placed into the bedding.
Wormeries are operated so as to take advantage of the worms’ tendency to eat and breed in an area and then migrate towards a source of fresh food and bedding.
Upward migration: Many wormeries consist of a series of trays that stack on top of each other, and encourage the worms to migrate upwards. Other designs such as the Hungry Bin and the various fabric wormeries also encourage upward migration. In these types, the worms leave the compost or “worm castings” behind them and this can be harvested.
Sideways migration: A wormery made in a wooden crate, a trough, or an old bath consists of a single compartment. In this application, the worms eat all of the food and all of the bedding, so after several months the worms and their castings need to be pushed over to one end of the container, and fresh bedding is placed in the other side (NOTE: bedding should always be thoroughly soaked before use, as worms need a moist environment). Feeding is resumed in the fresh bedding, and the worms will migrate over into the fresh side. After a few weeks, the compost can be harvested without taking out any worms, and the area just emptied should then be filled up with fresh bedding again.
What to feed the worms: most fruit and veg waste, bread and pasta (small amounts), manure from herbivorous animals, tea and coffee, green leaves from weeds, dead flowers. It is much better to chop everything up into small pieces so that the worms can eat them quickly and easily.
What not to add: citrus fruits and peels, onion and garlic, salty and spicy foods, meat or fish. Dog and cat poo can be composted but in a separate wormery, because they contain dangerous pathogens.