I'm curious - why worry about removing worms from the castings that you spread int he garden?
They seem to multiply rapidly in your worm bins, and presumably load up the contents with worm eggs (or however they reproduce). Once they hit their stride, aren't there always about as many worms as the bin can hold?
Why not allow 50% to 70% of the worms to "escape" each time you harvest the castings?
Adding worms to soil seems like something that would always be desirable, even if many or most of them won't make it through the winter.
Would their eggs last through a winter? Is there something like "Hardiness Zone" information for worm species? Like "red wigglers are cold-hardy down to Zone 5". Or maybe "cold-hardy in regions where soil does not freeze deeper than 12 inches"?
