Our hosta has already come up and is fairly large. Can we cut it back and divide it now?
Hosta – Dividing It
Certified GKH Gardening Expert
Most definitely and now would be the ideal time to do it, before it gets too hot. You can normally divide these plants anytime from spring through fall. Simply dig up the clumps you want to divide and split them with a spade shovel, getting anywhere from 2-4 (or more) smaller clumps, depending on the overall size. Make sure each new clump has some roots with it and replant elsewhere. This article should help you as well: https://www.gardeningknowhow.com/garden-how-to/propagation/propgen/dividing-plants.htm