Having recently moved, I hated leaving behind my previous outdoor worm bed which was loaded with PE worms, and some red worms which found their way. However, I just started another bed in my backyard and am amazed at how fast the worms moved in! I did add a few shovel fulls of soil that had a few worms from underneath a nearby tree. These few worms were small, but the ones in my bed are getting huge. I have attached a link with some pics..

Here is a link that might be useful: New outdoor worm bed