Ageratum Plant Growing & Care Guide for Gardeners

In this Gardener's HQ guide, we'll explore cultivating Ageratum plants in your garden, indoor spaces, and other settings.

Flossflower, Whiteweed, & Butterfly Mist: Cultivation & Garden Use

The Ageratum genus contains about 60 species. These may be annuals or perennials, but even perennials tend to be grown as annuals in gardens. They are native to Central America and the US.

Ageratum houstonianum
Ageratum houstonianum photograph by Nemo's great uncle CC.

Although this is a member of the Daisy family, Ageratum plants have distinguished fluffy flowers. These arise because their flowers lack the rays that are typically seen in the Asteraceae (Compositae) family.

Garden grown Ageratum plants tend to be short and are largely grown for their flossy flowers.

Flowers are mainly blue, but some species and cultivars may have purple, pink, or white flowers.

Unfortunately this plant can become a weed in areas that it does not belong to.

Ageratum Artist Purple
Ageratum Artist Purple photograph by Serres Fortier CC.

Some common names for the half hardy annual Ageratum include Flossflower, Garden Ageratum, and Tropical Whiteweed. They typically flower from June to late September.

Description of Flossflower

Ageratum can grow up to 24 inches (60 cm) in height. The plants may have downy white, pink, deep violet or pale blue flowers. Their height and color makes them very suitable for edging as they often form compact mounds, they are also ideal border plants and look attractive in containers.

Information on Ageratum and commonly grown garden species

Members of the Ageratum genus are native to central and northern America.

There are approximately sixty members of this herbaceous genera. Some of the most commonly grown species include Butterfly Mist (Ageratum corymbosum); Flossflower, Bluemink and Garden Ageratum (Ageratum houstonianum); Tropical Whiteweed (Ageratum conyzoides); Cape Sable Whiteweed (Ageratum littorale).

Commonly Grown Garden Species

Ageratum houstonianum Growing Guide. This annual plant is better known as the Flossflower. It blooms in early summer with fluffy medium blue flowers. The plant is tender to frost so start off indoors in colder areas with short growing seasons or grow in containers. It reaches from 4 to 18 inches (10 to 45 cm) in height. Flossflower makes a great edging plant, and can also be used in a rockery, or as a border or bedding plant. This plant is fairly tolerant to deer.

Ageratum conyzoides (Chick weed/ Billygoat weed). This South American native reaches up to 3 1/3rd feet (1 m) in height. It carries ovate leaves up to 2 inches (6 cm) in length. It is not recommended that you grow this species as it is invasive in Australia, The USA, Africa, and SE Asia (where it can interfere with rice production).

Ageratum littorale (Cape Sable Whiteweed). This is a native of Florida. It reaches an height of 20 inches (50 cm) and grows well in beach sand. It can bloom at any time of the year. Flowers maybe Blue, purple, or white.

How to Grow Flossflower

It is best to sow Ageratum species such as Flossflower on the soil surface, with a spacing of 6 to 10 inches (15 to 25 cm) for smaller species; and about 12 inches (30 cm) apart for larger species. Sow out after the last frost of spring.

Ageratum should be grown in a location that subjected to full sunlight, but with partial shading in the hottest months of hot areas. Ageratum grows well in most soils, though most species prefer an acidic pH between 5 and 6.


They require between 5 and 14 days to germinate. If initiating growth indoors then it is best to sow at a temperature of 21 to 24 degrees centigrade. Start off about six to eight weeks before transferring outdoors in spring, after the last frost; or in late summer.

Caring for Ageratum in the Garden

Ageratum species such as Ageratum conyzoides are easy to look after and requires watering only at the height of the summer. It is advisable to fertilise monthly and to remove spent Ageratum flowers by deadheading.

Further Information on Commonly Grown Ageratum Garden Species

Flossflower (Ageratum houstonianum)

The Flossflower is an annual Ageratum species, that can range in height from 12 to 39 inches (30 to 100cm). The leaves of the plant are oval at the stem and triangulate out, reaching a length of 1 to 3 inches (2.5 to 7.5 cm).

The flowers are usually blue, but as there are many varieties of floss flower available other colors are common, especially purple, white, or pink. The plant takes its name from the floss like flowers that it carries.

As a native to Mexico the Flossflower should be grown in areas that receive lots of sun; In very hot areas they also grow well in partially shaded conditions. It usually flowers throughout summer through to the first frost of autumn.

Butterfly Mist (Ageratum corymbosum)

Ageratum corymbosum
Ageratum houstonianum photograph by Rexness under creative commons licence.

This is a perennial garden plant that likes tropical conditions, in the USA it can grow in zones 8 to 11. The plant reaches an height of between two to four feet (60 to 120 cm) depending on species.

The seeds should be sown on the soil surface at a distance of 3 to 4 feet (90 to 120 cm) and require a soil pH of 5.5 to 7.5. Grow in full sunlight, or in partial shade in very hot areas. The flowers of butterfly mist are light blue in color.

Ageratum Growing and Care Guide

Common Names: Whiteweed, Flossflower, Butterfly Mist, Bluemink, Garden Ageratum, Tropical Whiteweed, Billy Goatweed, Cape Sable Whiteweed.
Life Cycle: Hardy annual.
Height: 6 to 48 inches (15 to 120 cm).
Native: Central and Northern America.
Growing Region: Zones 2 to 11. UK Hardiness H2 (Do not let temperatures drop below 32°F (0°C).
Flowers: Summer and autumn.
Flower Details: Blue, lavender, purple, white, pink. Umbels. Fluffy.
Foliage: Opposite. Cordate. Oval. Serrate.
Sow Outside: Surface. Following the last frost. Spacing 6 to 16 inches (15 to 40 cm).
Sow Inside: Germination time: one to two weeks. Temperature 70 to 75°F (21 to 24°C). Seven or eight weeks in advance. Transplant outdoors a few weeks after the last frost and in summer.
Requirements: Full sunlight or partial shade. Good drainage. Soil pH 5 to 7. Rich soil. Provide plenty of water in the summer, dead heading, monthly application of fertilizer.

Common Questions

How many members does the Ageratum genus have?

The Ageratum genus consists of around 40-60 species.

Do members of Ageratum make a good garden or landscaping plant?

Yes, Ageratum, or Flossflower, is popular in gardens due to its attractive and long-lasting blue flowers.

Which Ageratum species are most frequently grown by gardeners?

The most commonly grown species is Ageratum houstonianum (Flossflower).

Are members of the Ageratum fragrant?

Yes, Ageratum flowers have a sweet, slightly musky fragrance.

What is the perfect location to grow Ageratum?

Ageratum prefers full sun to partial shade and well-drained soil. They do well in both beds and containers.

Is Ageratum invasive in the USA, if so in which states?

Some species such as Ageratum houstonianum are considered invasive in some areas, especially in the Southeast and Hawaii.

How do I remove Ageratum from my garden?

Removal can be done by pulling or digging up the plants, making sure to remove all roots.


The Ageratum genus includes annual and perennial plants known as Ageratum. Native to the Americas, they feature fluffy clusters of small flowers in blue, pink, or white. Ageratum plants prefer well-drained soil and full sun or partial shade. They are low-maintenance and adaptable to various conditions. Regular watering and deadheading spent blooms promote continuous flowering. Ageratum is popular for borders, containers, and mass plantings, adding color and attracting butterflies.

Ageratum plants bring vibrant hues to gardens with their fluffy clusters of blue, pink, or white flowers. Their ability to thrive in different growing conditions and relatively low-maintenance nature make them a favorite among gardeners. Whether used as edging plants, in containers, or as mass plantings, Ageratum adds a delightful splash of color to the landscape, while also attracting butterflies, enhancing the beauty and ecological value of the garden.

I hope that you enjoyed this guide on how to grow Ageratum plants. You may also enjoy the following two growing guides: How to grow Fennel and Cenolophium denudatum.