'Hardy Ageratum' or 'Blue Mistflower' [Conoclinium coelestinum] (koh-no-KLY-nee-um: koh-el-ES-tee-num) Asteraceae:
The flowers are purple to lilac in color and plants grow around 2 feet tall. This native species to eastern North America is attractive in the garden and to butterflies. The upper stems tend to be tinted a dark purple and the flowers start off as tight buttons and open up to look very much like ageratum flowers. The long blooming plants spread by way of short underground runners - so give it some space. They grow best moister retentive soils and are tolerant of wet soils too, best in full sun to part shade. Blooms late summer into late fall. This species, like many other plants, is much more attractive when grown in the garden than when it it found in the wild, plants tend to grow large and fuller and clump up well under cultivation, while in the wild they tend to have one to few stems and smaller flower clusters. Good cut flower for mixed arrangements. If you have limited space or are the type of gardener that needs to have complete control over the plants in your landscape this might not be the plant for you, but if you have space and appreciate the beauty of plants that grow into nice sized clumps - this is a winner for the fall garden.