Most perennials bloom profusely during a specific season, such as spring, mid-summer or fall. Peonies bloom in late May through early June, tall iris flower in mid-June, and garden phlox blossom ...
When to Divide Perennial Plants: Generally, fall's the best time to divide perennial plants that bloom in spring and summer. (Conversely, spring's the best time to divide fall-blooming plants.) ...