Plants that are in soil without adequate drainage will grow the way you describe. They look fine for awhile, then they wither and curl down from the top. I had to build a raised bed of concrete blocks and mix a lot of sand into the soil in order to grow a.incarnata. I found an variety of a.tuberosa that grows well in clay from a company called High Country Gardens. They sell a lot of native desert, prarie, and mountain plants also, including one called Prarie Catch Fly (the stems are sticky, hence the name) that has fiery red flowers that hummingbirds love.