Conoclinium coelestinum

Species Native to Missouri
Common Name: blue mistflower
Type: Herbaceous perennial
Family: Asteraceae
Native Range: Central and southeastern United States, West Indies
Zone: 5 to 10
Height: 1.50 to 3.00 feet
Spread: 1.50 to 3.00 feet
Bloom Time: July to October
Bloom Description: Blue
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Naturalize
Flower: Showy
Attracts: Butterflies

Culture

Easily grown in average, medium to wet, well-drained soils in full sun to part shade. Prefers moist, fertile, humusy soils which do not dry out. Mistflower is a vigorous plant that spreads aggressively by rhizomes and self-seeding. In some areas of the U.S., the species is considered to be a spreading weed. Propagate by clump division in early spring. Plants will grow in wet areas. Taller plants may be cut back in summer to prevent flopping.

Noteworthy Characteristics

Conoclinium coelestinum, commonly called mistflower, is a late summer to fall-blooming herbaceous perennial that is native to the Eastern United States. It looks like annual ageratum and in that regard is sometimes commonly called hardy ageratum. But it is perennial and can spread aggressively by rhizomes. It typically grows to 1-2’ tall on downy purplish stems clad with coarsely-toothed, ovate-deltoid leaves (to 3” long). The flowers of this member of the aster family lack rays. Numerous small, fluffy, tubular, blue-purple flowers (to 1/ 2” across) with discoid heads bloom from July to October in dense flat topped terminal clusters (corymbs). In Missouri, mistflower is primarily found south of the Missouri River in low wet woods, at bluff bases, and in moist ground along streams, ponds, sloughs and ditches (Steyermark). It is also commonly called blue boneset. Conoclinium coelestinum is synonymous with Eupatorium coelestinum.

Specific epithet means sky-blue or heavenly.

Problems

No serious insect or disease problems. Some susceptibility to powdery mildew. Leaf miners and aphids may also visit. Plants tend to flop and may need support. Spreading tendencies must be watched, particularly if planted in the perennial border.

Garden Uses

Wild flower garden. Naturalized areas. Periphery of stream of pond. Open woodland garden. May be grown in borders as long as sited in an area where spreading roots will not interfere with other plants.