An old favorite with its fluffy round clusters, Ageratum houstonianum (Floss Flower) is one of the few annuals to tolerate light shade. A nonstop bloomer from mid summer to fall (Ageratum means 'long-lived' in Greek), it grows easily in shapely mounds ranging from 6-24 in. tall (15-60 cm) and mixes extraordinarily well with all other annuals and perennials. Its colors range from blue, purple, lavender to pink, red, white and bicolor, providing a nice contrast with the rest of the bedding plants. It is deer, rabbit resistant and attracts butterflies.
- Easy to grow, Ageratum houstonianum performs best in full sun in rich soils with good drainage and consistent moisture during the growing season. Don't let it dry out! Avoid overhead watering and provide good air circulation to prevent the plant from powdery mildew. Light shade is tolerated in hot summer areas.
- Excellent choice for beds, borders, edgings, mass planting, rock gardens or groundcovers. Perfectly suited to mixed containers too. Excellent as cut flowers (on the taller varieties).
- Easily grown from seed, starting indoors in late winter and transplanting outdoors after the danger of frost has passed. Alternatively, seeds can be sown in the garden after the last frost date. If you prefer live plants, they are available from many nurseries.
- Deadhead spent flowers to keep the plant tidy and promote profuse blooming. In warm climates, Ageratum may self-sow.
- Main cultivars are:
‘Hawaii’ Series flowers in shades of blue, white or pink. Very popular series.
‘Bavaria’ has white flowers with bright turquoise borders. Up to 1 foot tall.
‘Red Top’ has very striking bright magenta flowers on 3-inch heads. Up to 2.5 feet tall.
'Blue Danube' is a classic hybrid with purple-blue flowers in dense heads. Compact and reliable garden performer. Very free flowering.
'Blue Horizon' is one of the tallest (up to 18-30 in. or 45-90 cm) with lavender to purplish-blue flowers resembling asters. Great as cut flowers
‘Pinky Improved’ has showy flowers that are dark pink in the centers, fading to pale pink at their fringed edges. Compact and showy.
‘Southern Cross’ has bicolor flowers are white in the center, gradually turning to cornflower blue near the edge. Compact and showy.