The genus Sedum includes a group of starflowered succulents suitable for rock gardens to rooftops. Two additional star–studded sedum are making themselves at home in Columbia gardens alongside ‘Autumn Joy.’
Sedum sarmentosum is commonly called graveyard moss, gold moss, stringy stonecrop, trailing stonecrop, or star sedum. When a garden friend gave me a bareroot bunch of star sedum to try, I placed it in a 6” terra cotta pot and within days it filled the container and began trailing across the pavement in search of adventure elsewhere. To my surprise one morning the entire plant glowed yellow. Five–pointed star–like flowers covered the foliage for days before disappearing and leaving star–shaped chartreuse sepals behind.
I’m keeping my adventurous spirit in a pot for the time being. Hanging baskets and window boxes would allow it to cascade. Star–sedum makes a low, fast–growing groundcover which can be trimmed to control. Because this sedum spreads horizontally and forms a dense mat, it appeals to green roof engineers.
Propagation is very easy by division or cuttings. Some say it grows anywhere you toss it. One nursery propagates the plant by spreading the trailing stem cuttings on a sheet of moist potting soil. After giving the roots several weeks to sprout, they cut the sheet into small pieces as one would a sheet cake. Each piece becomes a new plant.
A second opportunity to see stars in flower form comes with Chinese sedum, Sedum emarginatum ‘Eco–Mt. Emei.’ Introduced by Georgia planthunter Don Jabobs, the oriental native has . round fleshy green leaves and yellow star–shaped flowers. Riverbanks Botanic Garden displays the plant as a groundcover. The plant enjoys the same growing conditions and uses as its close kin, Sedum sarmentosum.
These two sedums are among the stars of the Shanghai World Expo 2010 where an international green roof conference was held May 10. China has embraced green roof technology to tackle problems related to air pollution, clean water, and energy conservation. Sedums, many of which are native to China, offer low–cost, light weight, fast–spreading rooftop blankets of green reflecting their stars skyward.