Amsonia illustris

Known commonly as blue star, amsonias bear starry flowers from late June. Slow-growing perennials, they lack drama but make the perfect foil for a number of more dramatic and colourful plants. The different species are hard to tell apart, but Amsonia illustris has shiny green leaves and large flowers. All amsonias have milky sap, which can irritate the skin.

Grow Amsonia illustris in humus-rich, moist soil, in full sun or semi-shade. Divide in early autumn if necessary.