Planted coneflowers outdoors and they started to turn black. Sprinkled with Sevin dust and they continued to die. Pulled stalk out and no roots. Will they come back next year or are they dead? What was the problem - bugs or disease?
Certified GKH Gardening Expert
If the coneflowers started to turn black soon after they were transplanted, they probably died either of transplant shock or of overwatering:
If instead they flowered and then dried out, this is normal and just due to the lifespan of the flowers.
Also check whether any of these possibilities match, especially sweet potato whitefly: