Conoclinium [Eupatorium] coelestinum (Hardy Ageratum, Mist flower) - 1 gal

Blue Mistflower, also known as Hardy Ageratum, is a lovely late-blooming native wildflower. When it bursts into bloom in September, it is covered in flat-topped clusters of fuzzy, blue-violet to lavender-colored flowers that provide an excellent source of nectar for numerous pollinators. It is a total butterfly magnet! It is also a host to the furry little Ruby Tiger Moth and the ever-so-chic Clymene Moth. This plant can be somewhat aggressive as it spreads readily by seed and through vigorous rhizomatous growth, making it a good choice for meadows and large naturalized areas. Rabbits and deer tend to avoid the bitter foliage, allowing for easy establishment of a thick groundcover in areas where they can roam freely. If a shorter or more controlled specimen is desired, plants can be cut back by half in early summer. Blue Mistflower resents drying out and grows best in consistently moist soils.

Sources:
Growing and Propagating Wildflowers by William Cullina
Missouri Botanical Garden
Lady Bird Johnson Wildflower Center
Illinois Wildflowers
NC State Extension