The Genus Sedum
This is large genus of succulent plants native to Asia, Europe and North America. They are variable in size, leaf shape and flower color but the flowers are always five-pointed stars in clusters at the top of the stem. One odd problem that I have is that something eats the leaves in winter, chewing the tips first. It may be rodents or birds in search of moisture.
Crassulaceae, is a large family that is native to Asia, Africa, Europe and North America. Many of them have succulent leaves. Many species are cultivated as plants for the house and garden. Familiar members of this family include the jade plant (Crassula,) ghost plant (Graptopetalum,) kalanchoe (Kalanchoe) and hen-and-chicks (Sempervivum.)
Sedum adolphii (confused with S. nussbaumerianum)
The large succulent leaves of this robust Mexican plant are green with an orange to brownish cast when grown in bright light. It is a bushy plant in bright light. In shade, stems tend to trail. White flowers are borne on leafy stalks at the stem tips. Give it a sunny site with afternoon shade in a well-drained site or container. Reportedly, it is cold hardy in zones 8b and south.
Sedum nussbaumerianum is similar but oranger in color when grown in the sun and its stems are less upright. Some botanists believe that the two should be lumped under the name S. adolphii.
This plant may be found in specialty catalogs. It is propagated easily by stem cuttings and by single leaves.
I move my plant under a roof in winter to minimize exposure to rainfall. It survives winter lows in the low 20’s F with little damage but a low of 18 degrees caused the death of some of the stems. My plant flowers in February. The developing flower buds tolerated winter temperatures in the low 20’s F without damage.
Despite its name, the origin of this species is not known. Some botanists believe it is native to Asia. At a glance, it resembles Sedum acre. In comparison, it is a more compact plant with smaller leaves. Its short stems do not trail along the ground and it seems much better adapted to the Coastal Southeast. It bears clusters of tiny yellow flowers at the stem tips in spring. It grows well for me in a well-drained soil, in a sunny site with afternoon shade. It requires more water than most of my succulents. It is recommended for zone 7 to 9.
Plants are available from specialty catalogs. It is propagated easily by stem cuttings.
My plants grow very well in a container with weekly watering. It has grown poorly in an unirrigated site in the ground in my garden. They flower in April and early May. They have survived winter lows of in the upper teens F without obvious damage.
other Sedum species
a young Sedum dendroideum
I am have tried a few other stonecrops and continue to buy more. Many seem to benefit from afternoon shade and regular water in my zone 9a garden.
Sedum dendroideum is a Mexican species. It is a somewhat bushy plant that can grow to two feet tall or more. It resembles a jade plant (Crassula ovata) but its stems are more flexible and slender than a jade plant’s. It is reported to be cold hardy to 20° F. A young plant showed no damage on my porch when temperatures dropped into the low 20’s. I have not tried it yet but S. prealtum is reported to be similar with even greater cold hardiness.
Sedum pachyphyllum is another Mexican species that I tried. It is a spreading plant with fat, rounded leaves. It is reported to be cold hardy to 15° F. It required more water than most of my succulents and eventually died from my neglect.
Sedum palmeri has flattened, blue-gray leaves. Reportedly, it is cold hardy to zone 7a. Mid- to late winter flowers are bright yellow. I have grown this species in a container for years. In my zone 9a garden, this has been the most dependable of the spreading sedums. It shows no problems when winter lows drop to the upper teens but the leaves of this plant suffer from whatever is chewing stonecrop leaves in my garden.
Sedum rupreste (syn. Sedum reflexum), the blue spruce sedum has grown well at the University of North Florida in a container of good potting soil with irrigation. It died in the ground in my home garden. In zone 9a, it seems to require a little care to thrive.
Sedum spectabile (syn. Hylotelephium spectabile) struggles in the ground in my upper zone 9a garden. It grows well in a friend’s nursery with good potting soil and frequent irrigation.
Sedum tetractinum, the green penny sedum, is another plant found in local nurseries that requires regular irrigation. A plant in a shady, unirrigated part of my garden died soon.
It may not be wise to generalize, but it appears that the cold hardiest Mexican species may grow easily in the warmer parts of the Coastal Southeast. Many of the more familiar Sedum species that are common in local nurseries and in mail order catalogs are native to Europe. They seem to require more care. In particular, they seem to need regular irrigation in zone 9a.