Adriana from California asked me; "I've seen so much about sedum and sempervivum on blogs and everywhere lately - I'm very confused about the difference between them. Can you enlighten me, and also what kinds of uses are there for both of these plants?"
This is how I answered her;
Sedum and Sempervivum are two of my very favorite plants. They are related, as they both belong to the same family, the Crassulaceae, which also includes many other succulent plants such as Crassula, Echeveria and Jovibarba among others.
Sedum tends to be used for groundcovers in places such as green roofs and xeric gardens, where it will spread to fill the space available without being invasive or a nuisance.
sprawling stems with succulent leaves come in many colours and shapes,
and the starry clusters of flowers range from white, to yellow, to pink
and red. Many of the smaller Sedum are commonly used for container plantings too.
Taller border Sedum, such as Sedum spectabile and telephium, the most well known of which are Sedum spectabile 'Autumn Joy' and Sedum telephium 'Purple Emperor' are used in borders and where a taller plant is needed. They have broccoli like blooms in the late summer and fall.
an extensive group of hardy succulents, with a rosette forming type of
growth habit. They always grow from the center of the rosette in a
They spread by making 'chicks' which are attached with stolons from the mother hen, and will eventually spread this way to form a large colony. The flowers of Sempervivum are larger, and each individual bloom is a wide open flat faced star, usually borne in clusters.
Once the rosette blooms, it will die after forming seed.
of the Sedum and Sempervivum can be used in droughty and well drained
soils in full sun, where they flourish with a small amount of organic
matter and a mineral mulch like lava rock or pebbles.
So, to sum it all up - Sedum and Sempervivum are different genetically, yet compatible and can be grown in similar conditions. Their growth habits and rates complement each other, and their colours, changing as they do with the seasons add a texture and depth to the xeric garden.