Blue Mistflower: An overlooked beauty

Asters, mums, and goldenrod rightfully get a lot of the attention, but they are far from the only fall-blooming perennial flower to be celebrated in fall gardens. One that I’m particularly fond of that doesn’t get a whole lot of recognition is Conoclinium coelestinum, Blue Mistflower.

A native perennial wildflower found throughout the East Coast from Canada to Georgia, Blue Mistflower has a long bloom period, starting in mid- to late summer and lasting until the first hard frost of fall. While not part of the Aster genus Symphyotrichum, it is part of the Asteraceae, or Daisy, family, and thus shares some similarities with true asters. Mistflowers’ blooms are not the classic daisy shape one might expect from this family of plants, rather, the individual blooms are a fuzzy flat disc lacking the rays of a daisy. Flowers are a light shade of blue – baby blue, Carolina blue, sky blue, call it whichever you wish. This plant is sometimes called hardy ageratum, due to the visual similarity of its flowers to the annual ageratum.

Top:  Close-up of a cluster of blossoms. Middle left: Blooms appear to have flat tops. Photo: Kingdon, CC0. Middle right and lower left: Blooms come in pinks, blues, lavenders and in-between shades. Middle right: B. Peterson, CC-BY-SA 2.0 Lower left: Doohamlm, CC BY-SA 3.0

This native wildflower spreads by both rhizome and seed, and can become somewhat weedy if left unchecked. We have it growing in the Pitt County Arboretum in both the Butterfly Garden and Wildflower Garden, and with some occasional thinning it is relatively well-behaved. It is typically found growing along roadsides and in moist ditch banks, which shows the range of tolerance it has for different levels of soil moisture. It will tolerate a bit of shade, but flowers best in full sun. Bees, butterflies, and other pollinators enjoy the nectar-rich flowers and this plant is often included in pollinator-themed gardens for that reason. If you are growing blue mistflower in hopes of supporting pollinators, you may have better results in average to moist soils rather than dry ones. Plants will grow 18-36 inches tall and wide.

Gardeners may occasionally encounter another species of mistflower, Conoclinium greggii, which is quite similar in a number of ways from size to flower color. This species is native to the Southeastern United States. As you might expect based on that fact it is slightly less cold hardy, C. greggii will still likely function as a perennial in Eastern NC, but C. coelestinum is a better choice for our gardens under most circumstances.

Both species are relatively pest free, with the only real problems of note being an occasional minor infestation of aphids or powdery mildew. It’s a great plant to add late season color in pollinator gardens, native plant collections, water gardens, or natural areas.

Matthew Stevens is the County Extension Director and Horticulture Agent for North Carolina Cooperative Extension’s Pitt County Center. If you have questions about this article or gardening in general, please contact the Pitt County Extension Master Gardeners at [email protected] or 252-902-1705.