Sizing Up Sedum

Chris Schlegel

Sedums have long been a mainstay in perennial rock gardens and borders. Common traits among the various sedum species include fleshy, semi-evergreen foliage and small starlike blossoms. They differ widely in plant habit, and foliage size and color. Low-growing types, such as Sedum makinoi and Angelina thrive in rock gardens, while taller types, such as Autumn Joy, provide focal points in the perennial border.

Using sedums in containers is an excellent option, as well. Their tolerance of heat and drought make them perfect candidates for patio containers in sunny locations. Combining sedums with various succulents can result in unusual and extremely tasteful planters. The blue hue of creeping S. reflexum Blue Spruce can be mirrored with Senecio serpens, which has an upright habit. Sedum rubrotinctum features shades of pink and green that combine beautifully with other rose-colored components. The possibilities for creative containers are infinite!

The green roof movement offers yet another opportunity to utilize sedum in the landscape. Europeans were the first to popularize the concept of green roofs; however, the U.S. is now embracing the idea. With their shallow root systems and weather tolerance, sedums are the most popular genera for living roofs. The cold hardiness of sedums is variable; however, there are green roof installations in Zone 3 portions of New Hampshire where members of the genera have been used successfully.

Media selection and water management
Transplant rooted cuttings into well-drained, soilless media with a pH of 5.8 to 6.2. Proper irrigation is critical for growing a successful sedum crop. Water should be applied sparingly and the media should be allowed to dry somewhat between irrigations. Saturated media can cause root disease issues
and should be avoided. Conversely, extreme drying may result in foliage necrosis. The key is to maintain the optimal amount of moisture and porosity in the root zone.

Temperature and light
Sedums prefer fairly warm temperatures when actively growing. Night temperatures of 58F to 65F (14C to 18C) and day temperatures of 72F to 78F (22C to 26C) are ideal. They tolerate cooler temperatures, but will require longer crop times in those situations. We recommend high light levels in order to avoid long internodes. Light intensities should be in the 6,000 to 9,000 f.c. range.

Fertilizer
Sedums have moderate fertilizer requirements. A constant liquid feed of 100 to 200 ppm using a balanced fertilizer such as 20-10-20 or 17-5-17 is one means of satisfying the nutritional requirements. Controlled-release fertilizers may be used as well. The media EC should be checked periodically to assure there isn’t a salt buildup. Leaching with clear water may be necessary if EC levels are too high.

Growth control
The use of chemical growth regulators is generally not necessary provided that proper cultural conditions prevail. High light, adequate space and water management should result in nicely shaped plants. Pinching will enhance the branching of many varieties and is recommended particularly for larger pot sizes.

Pests and diseases
Aphids and fungus gnats are the most common insect pests encountered on sedum. They can be easily controlled with the use of a rotation of appropriate pesticides. 

Diseases such as Pythium and Phyto-phthora may occur if the media is too wet for long periods of time. Water management is the optimal way to avoid these diseases. If crops are grown outdoors and subjected to periods of wet weather, fungicide drench applications will reduce the likelihood of problems. Powdery mildew infections on sedum appear as brown scablike lesions with little powdery growth. Scout crops carefully as these symptoms are often not obvious in early stages. GT

Chris Schlegel is head grower for D.S. Cole Growers in Loudon, New Hampshire.