Common name: Ageratum, Mexican Ageratum, Flossflower
Family: Asteraceae, Aster
Height x width: 4-24" x 8-24"
Growth rate: moderate
Foliage: opposite leaves, usually oval with rounded teeth
Flowers: blue, white, pink 1/4" flower heads (tassel-like) in cymose clusters without ray flowers
Hardiness: annual
Soil: well-drained, moist, fertile
Light: sun preferred or part shade in zones 8-9
Pests and problems: root rot, powdery mildew, spider mites
Landscape habit, uses: edging or border front for low cultivars with mounded habit, mid to back borders for taller
Other interest: native of Mexico; genus from Greek words a- meaning not and geros meaning old age, refering to the flowers not appearing old for a long period
Other culture: remove flower heads to ensure continued bloom, prefer warm weather
Propagation: seed indoors to plant out (214,000 seeds/oz.) which germinate in 5-10 days, also latter in season by cuttings
Species:
houstonianum (hu-sto-nee-aa' num)--usually seen species, named for botanist Dr. W. Houston who brought plants back from Mexico and the West Indies
Cultivars: (of houstonianum), those marked * are most common
| Cultivars | height, in | flowers | other |
| 'Adriatic' | 8 | mid-blue | early, heat tolerant, common |
| 'Bavaria' | 9-12 | blue, white bicolor | |
| 'Blue Blazer' | 5-6 | deep-blue | common |
| 'Blue Danube' ('Blue Puffs') | 7 | bright blue | uniform, common |
| 'Blue Hawaii' | 8 | mid-blue | small leaves,compact,common |
| 'Blue Heaven' | 6 | mid-blue | heat tolerant |
| *'Blue Horizon' | 24-30 | mid-blue | vigorous, branched, good cut |
| 'Blue Jay' | 4 | powder blue | common |
| 'Blue Lagoon' | 8 | medium blue | uniform, compact, heat-tolerant |
| 'Blue Mink' | 12 | powder blue | early, tetraploid, common |
| 'Blue Ribbon' | 4-5 | mid-blue | compact, low |
| 'Blue Puffs':'Blue Danube' | |||
| 'Capri' | 8 | deep blue | compact, non-hybrid |
| 'Fine Wine' | 6-8 | burgundy red | compact |
| *Hawaii Hybrids | 8 | blue, purple, white | small leaves, compact |
| 'Madison' | 8 | blue | |
| 'Midget Blue' | 5 | bluish-mauve | |
| 'Neptune Blue' | 8 | mid-blue | |
| 'North Sea' | 8 | lavender-blue | reddish buds, common |
| 'Pacific' | 8 | purple-violet | early, uniform, common |
| 'Pinky Improved' | 6-8 | dusky pink | unusual color |
| 'Royal Delft' | 6 | deep violet-blue | compact |
| 'Southern Cross' | 8-12 | blue, white bicolor | good for cutting |
| 'Summer Snow' | 6 | pure white | common |
| Swing Hybrids | 6-8 | blue, rose, pink |
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