A worm tower not only enables worms do their work at composting, but it also helps them spread out and distribute the compost in your tank garden. This is such a low maintenance way of keeping nutrients cycling in your garden, and easy to put together.
All you'll need is a 3 or 4 foot piece of PVC piping (or a 12" concrete pipe) and a flower pot.
According to Ecofilms, be sure to use a food grade PVC pipe to avoid any chemical contamination - and the concrete pipe often works best. Punch holes in the side of the pipe. This is where the worms will travel back and forth between the compost and the garden patch.
Once you've got your pipe, the next step is to bury the tower half way down in your garden with half of the pipe sticking out the top.
Then, add some manure, compost worms (it's important to use compost worms), and secure with a flower pot lid. It's also important that you feed your worms every couple of days with vegetable scraps from your kitchen ... and voila! The worms will do the work for you!
via Eco Films