To be honest, I dig up the largest bunches in the late summer, split them according to the root mass (they seem to fall into clumps on their own)and plunk them into the garden soil in their new spot. I try to give them time to acclimate before winter (so I dig in late August/early September here in Michigan) and I mulch them the first winter with shredded leaves. I also dig up the newly seeded violets in late July and transfer them whole to their new site in the garden. Since I allow & encourage self seeding, I have literaly hundreds of new plants each spring. My neighbor loves to hear that it's violet digging time - we're trading violets for daylillies, and quite happy with our new plants.