One-flower Goldenweed is a high-altitude species of water-soaked soils. It enjoys full sun in my bog garden at 10,000 feet elevation. In nature, it is often associated with Epilobium alpinum (Alpine Willowweed) and Ranunculus adoneus (Snow Buttercup). It produces lots of large, showy flowers in mid-summer and lots of viable seed. It stays short and tends to sprawl a bit under cultivation but is never untidy.