Wormery with 2 stackable trays and a tap

The unit takes up approximately 56 cm by 38 cm of floor space and stands 66 cm tall, less than half a square metre. It can be installed in a kitchen, utility room, cellar, or garage, and outdoors provided it is sheltered from intense heat. Choose a temperate spot, away from direct light and far from the vibrations of a washing machine or refrigerator, which worms will avoid. If placed in a garage, raise it slightly off the ground to keep it clear of exhaust fumes. Its feet keep it away from the floor, which limits access for ants, and at 7.1 kg empty, it can be moved easily as long as the trays are not loaded.

At the start, place just one tray on the collection sump. Line it with roughly 5 cm of bedding made from unfluted brown cardboard, egg boxes, or shredded paper, moistened to the texture of a wrung-out wet sponge, with a handful of compost or potting compost. Place the worms on the surface and let them burrow down on their own, then wait a few days before the first additions, which should be small and finely chopped. Increase the quantities as the colony grows; allow 3 to 4 months for a worm composter to reach its full working capacity.

Your bin stays balanced when it receives roughly one third dry material to two thirds wet material. Fruit and vegetable peelings, raw or cooked, along with leftover rice or pasta without fat, provide the moisture; plain uncoated brown cardboard, egg boxes, unbleached kitchen roll and coffee grounds with their filter provide the dry material, while corrugated cardboard stays out, as its adhesive would end up in the compost. Cut melon and squash rinds and cores into pieces no larger than 2 cm. Keep garlic, onion, leek and shallot out of the bin, as they act as vermifuges, along with citrus fruit, meat, fish, dairy products and fats. An unpleasant smell almost always indicates waste the worms cannot process quickly enough, or bedding that is too damp: reduce inputs and add dry material.

After 3 to 4 months, the material in the bottom tray resembles fine compost and contains almost no worms: the worm castings are ready. To drive out the remaining inhabitants, place this tray at the top of the stack with the lid open, the light pushes them down into the trays below. Mix the worm castings with roughly two thirds of soil or compost for your plants and planters, and use it within 6 months if possible. The tray you have just emptied goes back to the top of the stack, ready to receive the next additions. During periods of absence, the colony can go 3 to 4 weeks without being fed.

The liquid drawn off at the tap is reserved for watering plants and should not be added to the fish water, while compost tea is prepared from a fully matured worm compost: a few large handfuls enclosed in a net bag are steeped in 20 litres of water kept continuously agitated by an aquarium air pump for 2 to 3 days, then the liquid is strained and diluted at a ratio of 1 to 10. It is applied as a root drench, and if it is introduced into an aquaponic system, this should only be done in small doses of around 50 ml, observing how the crops respond before adding more. Continuous aeration prevents anaerobic fermentation. The worm composting guide covers its other uses, and the article on deficiencies in aquaponics helps identify which crops stand to benefit.

The box contains the lid, the 2 working trays, the juice collection tray, its tap, and the 4 legs, along with a guide to worm composting and assembly instructions in French. The unit is assembled by hand: the tap fits onto the juice tray, the legs are placed underneath, then the first tray and the lid are put in position. The worm composter is designed by Tumbleweed, manufactured in Australia from 100% recycled plastic, and guaranteed for 2 years. For the dry bedding needed in the first few months, a bag of coarse wood shavings makes a useful addition to plain, non-corrugated cardboard.