Blue Mistflower
Plant of the Week March 20, 2023
Blue Mistflower (Conoclinium coelestinum)
By Kalli-Ann Binkowski, Anoka County Master Gardener Intern
I fell in love with these beautiful, fuzzy, purple-blue flowers the very first year. I picked this native flower up from a local garden center and it grew into a lovely two and a half foot plant. Its bright green leaves show up well in the shade. The fall show was what really stole my heart. By the first September, it covered itself in clusters of small, fuzzy blue flowers. From there, I decided I needed more blue mistflower in my garden. Other names for them include hardy ageratum, wild ageratum, and Conoclinium coelestinum (formerly Eupatorium coelestinum).
Getting more of this plant may be an easy task in the right conditions. Blue mistflower is often listed as weedy or invasive, though it is not on Minnesota’s invasive plants or noxious weeds list. That first year I cut off the seed heads and disposed of most. I placed one branch on the soil to reseed for the next year. One branch of seed pods was enough to grow a small lawn of seedlings! It was easy to pull most of them, but I allowed a few to grow and provide their fall flower show. I may not have needed to bother reseeding, as this native also spreads through rhizomes. Now I have several plants and did not remove the seedheads before they opened last fall. I may have a literal forest of lovely blue flowers come September. I’m not sure I’ll mind, but I will see what happens this year.
These blue mistflowers grow in my Zone 4b garden, but they are noted as hardy to Zone 5 on many nursery websites. They are most appropriately listed as a native in states south and east of Minnesota. I may have found just the perfect microclimate to grow these perennials outside their zone. They grow in the shade on the south side of a large ninebark bush and under an ash tree. The heavier shade of its location in my yard compensates for having drier soil than it prefers. Blue mistflower’s natural habitat is moist, well-draining soil. It grows in full sun to part shade such as low woods, wet meadows, and ditches. In winter my mistflowers get covered by the deep snowbank on the edge of my driveway. That may explain why the plant has survived our Minnesota winters.
I haven’t grown it for enough years to know how it will grow year after year in our zone. Will being on the edge of its zone tamp down its aggressive spread, or will a harsh winter kill it off entirely? Either way, I will enjoy those fluffy flowers as long as I can.
References:
United States Department of Agriculture. (n.d.). Plants profile for Conoclinium Coelestinum (Blue Mistflower): USDA plants. PLANTS Profile for Conoclinium coelestinum (blue mistflower) | USDA PLANTS. Retrieved March 11, 2023, from https://adminplants.sc.egov.usda.gov/java/profile?symbol=COCO13
