Native to the Eastern United States, Canada and the Caribbean
Also known as C. cœlestinum or Eupatorium coelestinum.
Flooms in late summer through fall
Leaves are small, round and coarsley toothed, arranged in an opposite pattern
High wildlife value for butterflies and birds as a source of nectar and food.
Spreads quickly in a clump formation, requiring constant maintenance to keep it from outcompeting other plants.
Requires rich, moist soil and full sun or partial shade to grow.
Hardiness zones 4-9
Sentimental and Symbolic Value
A delicate flower of the aster family, which carries symbolism in Western cultures of love and frailty. Its use in funeral planting such as that of Mount Auburn Cemetry in Cambridge, MA evokes feelings of calmness and peace. Its connotation with frailty could then also be seen as a subtle motif of memento mori in such plantings. Asters are commonly laid on the graves of soldiers, expressing that same sentiment of the fragility of life.
Its flower's persistence into fall is taken as a symbol of hope, popularized by the poem A Late Walk (1915) by Robert Frost; "the faded blue of the last remaining aster flower" is the last sign of a life in a dying world.
Specimen photographed at Mount Auburn Cemetery in Cambridge, Massachusetts
Plant History and Etymology
The generic name comes from the Greek κῶνος (kônos), meaning "cone", and κλινίον (kliníon), meaning "little bed". The specific epithet is possibly derived from the Latin cœlestis, meaning "heavenly". The plant has long been abundant in wet meadows, thickets and other very moist areas. It is cultivated for its beauty, leading to it escaping its natural habitat and invading others. It is not officially invasive in Massachusetts, but it is widely considered a pest. It was thought to grow from the mist of its native wetland habitats, leading to its name.
Design Considerations
The plant has very showy, corymb flowers coming in blue, pink and purple colors. These flower bloom late, usually from July through October, creating diverse visual interest through the fall when most flowers are already gone. Its fast-growing and clump-forming nature, as well as its resistance to some major challenges such as deer, fire, and saturation, allows it to be used effectively in a mass planting or border, but this also means that it requires constant maintenance to ensure that it does not become weedy.
Sources
“Conoclinium Coelestinum (Ageratum, Blue Boneset, Blue Mistflower, Blue Mist Flower, Hardy Ageratum, Mistflower, Wild Ageratum) | North Carolina Extension Gardener Plant Toolbox.” 2021. Ncsu.edu. 2021. https://plants.ces.ncsu.edu/plants/conoclinium-coelestinum/.
“Mistflower.” 2021. Bellarmine.edu. 2021. https://www.bellarmine.edu/faculty/drobinson/Mistflower.asp.
“Flower Meanings: The Language of Flowers.” 2021. Almanac.com. 2021. https://www.almanac.com/flower-meanings-language-flowers.
“Aster – Meaning and Symbolism - Symbol Sage.” 2020. Symbol Sage. September 28, 2020. https://symbolsage.com/aster-flower-meaning/.