Hi there. I planted 10 sedum tetractinum ‘Coral Reef’ along my front walkway last year and they have done very well until recently. Nine of them turned copper-coloured at the end of July, while only one remained green. I believe they should still be green at that time of year. Any idea what’s going on? They are all in a mostly sunny location and receive the same amount of water. Clay soil, Zone 6b.
Thank you for contacting Toronto Master Gardeners.
Sedum tetractinum ‘Coral Reef’ or Chinese sedum is a drought tolerant, herbaceous perennial that is relatively easy to grow and maintain in dry to average moisture, very well-drained soil in full sun. According to the Missouri Botanical Garden, it needs good soil drainage to perform well, and should not be overwatered. Connon Nurseries reports that this plant will often die in standing water.
It is not particular as to soil pH, but grows best in poor soils, and is able to handle environmental salt. It is highly tolerant of urban pollution and will even thrive in inner city environments. It tolerates rabbit and deer.
Note that the plant’s round green leaves naturally turn reddish-bronze in autumn, normally not July. Something is bothering these plants. Given this plant’s characteristics, I suspect that your sedum problem may be a case of too much water.
Make sure your sedums are planted in soil that drains well. You can improve soil drainage by adding organic matter such as compost.
Also, ensure that the plants are not overwatered. This past summer was very hot, requiring gardeners to water frequently. You may have inadvertently overwatered the sedums while watering the shrubs beside the plants.
Good luck with rehabilitating your sedums.