Experts and BHG readers answer.
Thinning and transplanting
Well it depends on which perennials you want to move. In the fall, it's best to move peonies, lilies, daylilies, hostas, bearded iris and Oriental poppies. All others are best transplanted in the early spring just as they are breaking dormancy. You can certainly buy lilies, daylilies, etc in the spring, but for established plants, last summer and fall is best. For specific information you can visit all these plants on our Plant Encyclopedia on this website.