From: Diana, Michigan
I have been able to divide hostas at any time the plants are visible, as long as it's not hot and dry outside. The easiest time is early spring when they are still small. If you are moving them to another site or have to wait to re-plant them, make sure to dig them up with the surrounding soil and plant snugly in a leftover pot, plastic or clay, from the nursery. (We all have vast quantities of those!) Keep moist until you can plant it at the new site.