You can purchase "red wiggler" worms at some nurseries, bait shops, sporting goods stores, and online (see our resource list).  Also, check Craigslist and ask around your community because indoor composting with red worms is very popular!  Nightcrawlers will also aid the system by working the full soil column and creating pathways to the compost. Common earthworms are not recommended, as they will not flourish in the Garden Tower environment.  Each Garden Tower comes with a 15% off coupon for one of our favorite worm farms which provides a high quality product at a very reasonable price: Uncle Jim's composting worms.