Experts and BHG readers answer.
Mushy black stems on sedum
A stem rotting fungus can attack sedums, especially if conditions are wet or air movement is poor. You may be able to control the problem by changing the environment that the plants are growing in: thinning to improve air flow; moving to a sunnier location to promote faster drying; amending the soil to improve drainage. If the problem persists, you may need to apply a protective fungicide spray.