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Ageratum houstonianum ‘Dondo Blue’ (photo courtesy of Kimberley Navabpour)
Ageratum houstonianum ‘Dondo Blue’ (photo courtesy of Kimberley Navabpour)

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Zone
Zones 1-24
Full Sun
Full
Regular Water
Moderate

Ageratum houstonianum

Floss Flower

Annuals, Flowers

Native to Central America, West Indies. Easy-to-grow, dependable plants that bloom in summer and fall; they can be grown as winter annuals in mild-winter climates. Hairy, soft green leaves are roundish, usually heart-shaped at the base. Dense clusters of tiny blue flowers resemble powder puffs. Most floss flowers form foot-wide clumps. Low growers make excellent edgings or pattern plantings with other annuals of similar size. Taller types provide good cut flowers. All grow best in rich, moist soil.

Dwarf kinds (4–6 in. high) include ‘Blue Blazer’, ‘Blue Danube’, ‘Blue Surf’, and ‘Royal Delft’. Somewhat taller (9–12 in.) types include ‘Blue Mink’ and ‘North Sea’. ‘Capri’ and ‘Southern Cross’, to 1 ft.high, have clusters of blue flowers with white centers. ‘Blue Horizon’, to 2 1/2 ft. tall, is good as a mid-border plant and for cutting. Good varieties in other colors are bright pink ‘Swing Pink’ (6–8 in.), deep pink ‘Red Top’ (2–2 1/2 ft.), and white-blooming ‘Summer Snow’ (9 in.). Plants in the Artist series are compact, strong growers to 8–18 in. high; they bloom profusely in shades of blue, violet, purple, or rose.

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