Last year I purchased some worm castings at the Olympia Farmers Market. It took me a while to use the whole bag and was very surprised to find my very own mini worm farm when I dumped the remainder into a large plant pot. So I let them be. I insulated it a bit for the winter and hoped for the best.
This past spring, I dumped out the bucket to find they had multiplied. I scooped them all back up and committed to providing a worm habitat. I studied up on what they need, bedding, food scraps, room to spread out and do their thing (i.e., make compost). They might get something fancier than the multi-bucket system they have now. Maybe a larger multi-bucket system!