Which perennials can be divided in late summer?
The best time to divide perennials varies with the different plant species. Late summer/early fall (September in Iowa) is a good time to dig and divide peony, daylily, garden phlox, hosta, lungwort, and hardy geranium. Late summer/early fall division gives the plants several weeks to get re-established in the landscape before winter. Perennials divided in late summer/early fall should be mulched with several inches of straw or pine needles in mid to late November. Mulching helps prevent repeated freezing and thawing of the soil (during the winter months) that can heave plants out of the soil.