Scientific Name: Ageratum houstonianum Miller
Synonym: Ageratum mexicanum
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Recommended Temperature Zone:|
sunset: All zone
Frost Tolerance: Semi hardy in Phoenix, or plant after last frosts
Sun Exposure: Full sun, light shade in Phoenix for the summer
Origin: Mexico, Belize, and Guatemala
Growth Habits: Annual from 6 to 18 inches tall (15 to 45 cm) depending on variety
Watering Needs: Regular water, subject to root rot if the drainage is bad.
There are many species of Ageratums. The species generally cultivated is Ageratum houstonianum. The Floss Flower has clusters of lavender, blue, pink, or white flowers depending on cultivar. 'Blue Danube' is a recommended hybrid variety. It provides an abundance of summer color. They can also make long lasting dried flowers.
It is best used in edging or borders of beds. Space the dwarf forms 6 inches (15 cm) apart, and the tall forms 12 inches (30 cm) apart. Check for white flies and aphids.
Fluffy clusters of lavender-blue flowers grow on top of compact, neatly-formed plants. Ageratum's low maintenance flowers fall cleanly from the plant as they fade, and are replaced through the season.
Start seeds indoors in early spring. Do not cover seed with soil as light aids in germination, they germinate in 5 to 10 days at 70°F (21°C). Keep soil moderately moist during germination. Young seedlings, indoors, need lots of light and grow better around 60°F (16°C).