Sedum

Types of sedum

Botanists have moved many garden sedums into three smaller genera. Plant labels mostly still say “sedum”, so this page covers all four.

• Upright sedums (Hylotelephium). Clump-forming plants with upright stems and flat heads of tiny, star-shaped flowers at the tips in late summer or fall. Autumn Joy is the best known: about 2 feet tall, with flowers that open pink, deepen to rose-red and fade to copper.
• Creeping stonecrops (Phedimus). Low, semi-evergreen mats 2–6 inches tall that spread 2–3 feet. Dragon’s Blood, sold for years as Sedum spurium, has green leaves tinged purplish-red in spring that turn red in fall.
• Needle-leaved stonecrops (Petrosedum). Mats of pointed, cylindrical leaves that look like little conifer shoots. Angelina (yellow, turning red-orange in cold weather) and Blue Spruce (blue-gray) are both cultivars of Petrosedum rupestre, still usually sold as Sedum rupestre or S. reflexum.
• Sedum itself. Still about 500 species. Mountain stonecrop (Sedum ternatum) is a native of the eastern US and Canada that grows in part to full shade. Burro’s tail (Sedum morganianum) is the odd one out: a trailing Mexican houseplant, hardy outdoors only in zones 10–11.

Sedum as ground cover

Creeping types grow 2–6 inches tall and spread a few feet in every direction, but slowly. To fill a bed faster, set plants 8–12 inches apart, or push cuttings into the soil across the area and keep it lightly moist until they root. They suit slopes, rock gardens, wall tops, containers and green roofs: anywhere sunny where water drains away fast. For a shady spot, mountain stonecrop is the one to try.

When to plant sedum

In spring as growth starts, or in fall while the soil is still warm. Water new plants for their first few months. After that, rain is usually enough except in long dry spells, though pots need watering more often. Divide clumps in spring and take stem cuttings in early summer. Don’t throw away fallen leaves: pressed into soil, they root and make new plants.

Sedum care in brief

Full sun and lean, gritty soil. Shade, rich soil and fertilizer all make tall sedums weak and floppy, and most need little or no feeding. To keep Autumn Joy types compact, cut the new stems back by half in late spring. Most garden sedums are cold-hardy, generally across USDA zones 3–9, and some take −40°F (−40°C). Wet winter soil is what rots them. You can leave the dead flower heads standing over winter and cut them down in spring.

Pets: ASPCA lists burro’s tail and Sedum album as non-toxic to cats and dogs. NC State rates Hylotelephium as low severity, with possible stomach upset.