These buttercup relatives spread their sunny goblet flowers in woodland borders in early spring. In fact, for many gardeners, they're the spring season's first flower. Winter aconites aren't as widely known or used as crocus, but are equally charming when they pop up in very early spring. Aconites spread easily in humus-rich soil and can be planted either as tubers or seed. The cup-shaped flowers are surrounded by a fringed collar of long leaves.