Can I plant perennials in late summer?
Late summer (late August to mid-September) is an excellent time to plant many perennials. It is also a good time to move or divide perennials, such as peony, daylily, garden phlox, and oriental poppy. Perennials planted in late summer should be mulched with several inches of straw, pine needles, or other materials in late November. Mulching helps prevent repeated freezing and thawing of the soil that can heave plants out of the ground. Plants heaved out of the soil may be severely damaged or destroyed due to drying of the exposed plant crowns and roots.