True, a few perennials such as peonies may go for decades, even a half-century without requiring lifting, dividing and replanting. Most perennials, however, perform better with more frequent attention--perhaps every three to five years, rarely a decade apart. October is a good month for most of this work. Even when cut back, divided and replanted, the soil will not freeze for several weeks, allowing continued root growth.
Mark before lifting those that are the most prized, best performers. Older advice to lift clumps, is to drive in two garden forks back-to-back, and push them together to pull apart the perennials. Why most gardeners would own two forks makes one wonder. And just try it on a well-established growth of hostas or daylilies. A well-sharpened turf edging tool works as well. Split into pie-shaped pieces, discarding the centre, older played-out portions. Clean out weed roots from those to be saved.
It may seem hard, but avoid replanting everything. Ask friends, relatives and neighbours if they would like to share the wealth. Many community organizations welcome such contributions for their fall fund raising sales.
