I had some requests to post this up again…
The easiest recycled wormery I’ve come across is at the Yalding Organic Gardens in Kent. It’s made with three fairly large polystyrene boxes – the type used for packing vegetables or fish. Ask around your local market for spares. Quite often, they’re left at the end of each day for waste collection, so it shouldn’t be a problem finding some. Each box usually comes with a lid, but you only need one: discard the others or use them as seed trays.
Make a hole in the centre of the bottom box, 2.5cm (1 inch wide. Place the box on two small columns made of some scrap material like old wood, bricks or concrete blocks. The hole in the bottom box allows excess moisture to run out. Place a small container underneath and then dilute the liquid that collects and use as a plant food. It’s powerful stuff – use ten parts water to one part worm juice. Take the second box and make seven or eight holes in the bottom. These holes are for the worms to climb up and down between the boxes so they need to be at least worm-sized (remember that baby worms grow fatter every day!). Place this box on top of the first. Take the last box, make the same number of holes and place on top of the second. Put the lid on top.
To start, place kitchen scraps and small amounts of scrunched-up (not flat) cardboard in the bottom of the first (single holed) box (or some shredded bills mixed with a few leaves) for bedding, along with 100 tiger worms. Keep on filling with kitchen scraps and a little bit of cardboard and paper. When the box is full, place the next box on top of it (one with several holes) and start filling it. When that is full, do the same with the top box. The worms will move through the holes between layers in search of food. By the time the top box is full of food waste, the bottom box should be full of worm casts. Take it out and empty the contents (being careful to lift any worms you dislodge back into the wormery). You can put it straight onto the soil or use it as part of a mix for potting compost.
For more info get hold of The Little Book of Compost.
You can get worms from http://www.greengardener.co.uk/wormeries.htm (prices start at £15.00), http://www.recycleworks.co.uk/worms-for-composting-c-288.html (prices start at £11.00), http://www.wigglywigglers.co.uk/shop/foundproducts.lasso?-nothing&-operator=cn&product_name=worms&-session=shopper:56859BDC0f0a8148F3Rpg13F9513 (prices start at £12.50).