Family: Asteraceae
Common Name: Floss Flower

Some plants of this genus of around 40 species of annuals, perennials and shrubs native to the tropical Americas have become naturalized and highly invasive in tropical and warm zones. The only species commonly cultivated as a half-hardy annual is A. houstonianum, the annual floss flower or rather its many cultivars which are used for summer bedding.

Species

A. houstonianum, which is native to tropical Mexico, has dull, hairy, heart-shaped leaves and fluffy flower heads in lavender, blue, pinkish mauve or white. It grows to about 45 cm (18 in) in height. Many cultivars have been produced for summer bedding, with flowers in shades of blue, from light to dark, shades of pink and mauve, and also white.

Cultivation

Ageratum prefers full sun but will tolerate some shade. It will grow in poor soil if it receives lots of water in dry weather. It is raised from seed sown in a heated propagating case in a warm greenhouse during early spring. This will produce young plants for setting out in bedding schemes and patio containers in late spring or early summer, when the frosts are over. It is easily raised and seed germinates freely in the right conditions.

Climate

Frost-free conditions are needed for Ageratum.