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Products > Ageratum corymbosum
Ageratum corymbosum - Floss Flower
Image of Ageratum corymbosum
Habit and Cultural Information
Category: Shrub
Family: Asteraceae (Sunflowers)
Origin: North America
Evergreen: Yes
Red/Purple Foliage: Yes
Flower Color: Blue
Bloomtime: Spring/Fall
Fragrant Flowers: Yes
Synonyms: [Eupatorium coeruleum, Bartlettina sordida?]
Height: 3-4 feet
Width: 3-4 feet
Exposure: Cool Sun/Light Shade
Irrigation (H2O Info): Medium Water Needs
Winter Hardiness: 15-20 F
Ageratum corymbosum (Floss Flower) - A long lived small evergreen subshrub (in frost free gardens) that grows at a moderate rate to 3 to 4 feet tall by as wide with well branched stems holding velvet textured broad heart-shaped leaves that emerge a purplish green color and then to dark purple before turning greener with age. In early spring appear the 6-inch-wide heads of small lavender-blue composite flowers that last for several months with good rebloom in summer and fall.

Plant in full coastal sun to bright part shade (morning sun is great!) and irrigate regularly to occasionally. Evergreen in frost free locations and root hardy to around 15 F. This is a very attractive 'everpurple" plant in the garden and it also makes a nice filler plant in a bouquet. It is a favorite nectar plant for many butterflies, particularly Queens (Danaus gilippus) and those in the Sulphurs group (Subfamily Coliadinae). Cut back in summer after first flowering cycle to tidy of the plant and get a full flush of new flowers.

The native range of Ageratum corymbosum is from Arizona and New Mexico south to Nicaragua but some consider this plant to be a form of the larger Bartlettina sordida from the cloud forests in central Mexico that previously was known as Eupatorium sordidum. The name for the genus Ageratum comes for the Greek words "a" meaning "not" and "geras" meaning old age combining to mean "non-aging" in reference to the longevity of the flowers and the specific epithet is a reference to the flat headed corymb inflorescences of this plant. The genus Bartlettina honors the American botanist, biochemist, and anthropologist Harley Harris Bartlett Voss, a noted expert on tropical botany and the name Eupatorium is one Linnaeus coined from the Greek name Mithridates Eupator, the king of Pontus to describe various herbs. The taxonomical differences between these three genera is slight to all but those studying these plants and it is often difficult to determine what the proper identification is but since we received this plant as Ageratum corymbosum, we continued to list it as such.

First alerted to this plant by our good friend the Meadow Master John Greenlee who brought us a bouquet of them from his garden for us to enjoy. He had purchased his plants from Annie's Annuals and we received our cutting stock plants from there as well and have grown this attractive plant since 2022. 

This information about Ageratum corymbosum displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.