Bountiful Gardens

The Autumn Cloud: Electric Blue Late-Season Color with Conoclinium coelestinum

The Snapshot

• Common Name: Blue Mistflower, Hardy Ageratum, Wild Ageratum

• Scientific Name: Conoclinium coelestinum (formerly Eupatorium coelestinum)

• Origin: Native to the Eastern and Central United States

• Hardiness: Zones 5 – 9

• The "Vibe": Soft, ethereal, and explosive; like a low-growing blue cloud.

Why We Love It

Mistflower is prized for its unique texture. Its flowers are composed of hundreds of tiny, thread-like fringe petals that create a "fuzzy" or "misty" appearance. While many blue flowers lean toward purple, Mistflower is a true, vibrant cerulean. It is a vigorous grower that spreads to form a dense, weed-smothering groundcover, making it an excellent choice for filling large areas that need a burst of life from August through October.

Ecosystem & Wildlife Impact

• Pollinator Magnet: This is a "top 10" plant for butterflies. It is particularly famous for attracting Monarchs during their fall migration, as well as Buckeyes and Swallowtails.

• Specialist Bees: It provides a critical late-season nectar source for native bees and honeybees preparing for winter.

• Native Host: It serves as a host plant for several species of moths, including the Clymene Moth.

Designer Tips: Where to Plant

• The "Rain Garden" Edge: Because it loves moisture, it is the perfect companion for the outer edges of a rain garden or a low-lying area.

• The "Sunset" Duo: Plant it in front of Goldenrod (Solidago). The electric blue of the Mistflower against the bright gold of the Goldenrod is one of the most stunning color pairings in the autumn landscape.

• Living Mulch: Use it to fill the gaps between taller, leggier perennials like Joe Pye Weed or Ironweed.

Designer Pro-Tip: Blue Mistflower is a "social" plant—it likes to roam. It is best used in naturalistic designs or large borders where it has room to weave between other plants. If you have a small, formal space, consider planting it in a large container or a bed with defined edging to keep its enthusiastic rhizomes in check.

Stories from the Garden

"I planted a small patch near my downspout. Two years later, it’s a stunning blue carpet that butterflies cover every September. I used to have a muddy mess there; now I have a butterfly sanctuary."

— Terrence W., Zone 6 Gardener

A Growing Story: The Blue Wave

A customer told us they thought their garden was "done" for the year in late August. Suddenly, their Mistflower erupted. They said that from their kitchen window, it looked like a literal wave of blue water was flowing through their flower bed. It’s now the plant they look forward to most every autumn.