Now’s the time to plant perennials, transplant perennials ... Once you’ve brought home your new perennials, make sure to water them thoroughly before planting. Hold the pot under water until no more air bubbles rise to the surface.
Even after this treatment, you’ll still need to water them immediately after planting – it’ll rinse earth around the roots, ensuring good soil contact. ... or divide them Division encourages older, woody perennials to grow vigorously and is the simplest way to propagate them. Dig deeply around the plant, slice it with a sharp knife or spade into fist-sized segments, and plant each one anew. Springtime is the right time for division for most perennials. Spring and early-summer bloomers should only be divided after they’ve flowered, however. And perennials with a pole- or heart-shaped root cannot be propagated in this way at all.