I tend to agree, that Echinacea should be pretty simple and most often thrive on neglect. If the leaves go right from green to brown or with brown spots, that sounds like a fungus. Different fungal problems can be easy for them to get if they are too wet or stay wet. It is somewhat easy to overwater Echinacea. They really like to start out on the dry side and then stay pretty dry while growing.
We grow our Echinacea on the dry, sandy gravel hill side of the property. Basically we plant them and walk away. During last summer's drought I think we watered them 2 or 3 times, but only when the foliage was completely wilted. A couple years ago we killed a whole bunch in pots after they got watered and fertilized while still dormant. They just weren't ready for any moisture
After comparing all of these last summer I am about ready to give up on Twilight. They were really weak, yet the other varieties near them grew great. I'll just have to see how they do next year.
Last fall we were watching several seedlings from Sunset. They have been very robust, growing larger than Sunset, but unfortunately just as they were starting to bud the frost hit them. A couple looked like they would be lighter colored and others looked like they would be darker. I'm kind of anxious to see them bloom! The only other seedling I got was from Harvest Moon. It looked just like the regular purple coneflowers (pink) but was fragrant
