A Worm Tower is basically a length of pipe buried halfway in the ground with holes drilled in the buried part for worms to get in and out. Food scraps are added directly to the tower instead of into your composting bin, and are eaten by worms already living in the target part of your yard. You can add Worm Towers to your full blown vermiculture / vermicomposting regime or just use them by themselves, particularly in raised beds. Several steps and lots of time can be eliminated for some of your composting by simply delivering food waste directly to the worms, directly on to the garden.
Build Your Own Worm Tower in Just 3 Simple Steps
Drill ¼+ inch holes into a PVC or plastic tube so that the worms can move freely in and out. The tube should be anywhere between 2 and 2 ½ feet long, 4 to 8 inches in diameter. Drill on tarp or bed sheet to catch the bits of plastic.
STEP 2
Prepare a hole in the ground and bury the tube so that only 4-6 inches remain above the surface. Back-fill around the tube but not in it, making sure that all of the holes are below ground. A piece of window screen and a flower pot as a cover will help keep out flies.
STEP 3
Fill the tube about half-way up with a mixture of moist organic matter (straw, shredded newsprint, leaves, etc.) and kitchen scraps. This is the food and bedding for the worms. Add a handful of red wigglers and you’ll be ready to go. To maintain the worm tower just add kitchen scraps as available and water it in dry weather to keep the worms and the surrounding soil moist.
(Source)