Blue mistflower (Conoclinium coelestinum)

Blue mistflower

Features and 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.

Care and Maintenance

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.

Blue mistflower (Conoclinium coelestinum) Requirements

Hardiness zone	5 - 10
Sun light	Full sun to part shade
Water	Medium
Maintenance	Medium

Common 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.

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.

Blue mistflower (Conoclinium coelestinum) Details

Common name	Blue mistflower
Botanical name	Conoclinium coelestinum
Plant type	Herbaceous perennial
Family	Asteraceae
Hardiness zone	5 - 10
Water	Medium
Maintenance	Medium
Flower color	Blue
Flowering period	July - Oc- ber
Height	1.50 to 3 ft.
Width	1.50 to 3 ft.