Ageratum houstonianum
Common Name(s):
- Phonetic Spelling
- a-ger-AE-tum ho-stone-ee-AE-num
- Description
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A frost-tender herbaceous annual to 1/2-1' tall, mounding with clusters of fluffy, aster-like flowers that should be planted with 10-12 inches of space. Genus name comes from the Greek "a" meaning not and "geras" meaning old age because the flowers hold their color for a long time.
Forms clumping mounds with colors of pink, white & blue from May through October. Dependable flowering annual. Confused with ageratums that are perennials with tall, erect stems and leaves well-spaced out, but similar in appearance with leaves and flowers.
This plant is moderately drought tolerance but prefers rich, moist, well-drained soil as well as full sun. It is good for beds and containers, blooming from spring to frost. Taller varieties make good cut flowers. This plant is seldom damaged by rabbits and deer. Used for edging or low massing plant in bed. Relative pest/disease free
Insect Pests, Diseases, and Other Plant Problems: susceptible to powdery mildew. Some cultivars have shown excellent resistance to phytophthora. See Phytophthora Root and Crown Rot in the Landscape.
Family name Asteraceae (Compositae)
Quick ID Hints:
- Mounded herb as wide as tall, often 6"
- Terminal cluster of small heads
- Flowers all tubular, tassel-like
- See this plant in the following landscape:
- Cultivars / Varieties:
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- 'Blue Danube'
Excellent resistance to phytophthora. - 'Blue Horizon'
Excellent resistance to phytophthora. - 'Leilani Blue'
- 'Neptune Blue'
- 'Redtop'
- 'Summer Stars'
- 'True Blue'
- 'Blue Danube'
- 'Blue Danube', 'Blue Horizon', 'Leilani Blue', 'Neptune Blue', 'Redtop', 'Summer Stars', 'True Blue'
- Tags:
- Cultivars / Varieties:
-
- 'Blue Danube'
Excellent resistance to phytophthora. - 'Blue Horizon'
Excellent resistance to phytophthora. - 'Leilani Blue'
- 'Neptune Blue'
- 'Redtop'
- 'Summer Stars'
- 'True Blue'
- 'Blue Danube'
- 'Blue Danube', 'Blue Horizon', 'Leilani Blue', 'Neptune Blue', 'Redtop', 'Summer Stars', 'True Blue'
- Tags:
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Attributes:
- Genus:
- Ageratum
- Species:
- houstonianum
- Family:
- Asteraceae
- Life Cycle:
- Annual
- Country Or Region Of Origin:
- Central America
- Wildlife Value:
- Plant is seldom damaged by deer or rabbits and attracts butterflies.
- Play Value:
- Wildlife Food Source
- Particularly Resistant To (Insects/Diseases/Other Problems):
- Rabbits, deer, and drought. Some cultivars resistant to phytophthora.
- Dimensions:
- Height: 0 ft. 6 in. - 1 ft. 0 in.
- Width: 0 ft. 10 in. - 1 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Annual
- Woody Plant Leaf Characteristics:
- Deciduous
- Growth Rate:
- Medium
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- High Organic Matter
- Soil Drainage:
- Good Drainage
- Moist
- Available Space To Plant:
- Less than 12 inches
- USDA Plant Hardiness Zone:
- 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b, 11a, 11b
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Fruit:
- Fruit Type:
- Achene
- Fruit Description:
- Fruit is a cypsela which is a type of achene.
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Flowers:
- Flower Color:
- Blue
- Pink
- White
- Flower Inflorescence:
- Cyme
- Flower Value To Gardener:
- Good Cut
- Showy
- Flower Bloom Time:
- Fall
- Summer
- Flower Shape:
- Tubular
- Flower Size:
- < 1 inch
- Flower Description:
- Fluffy, aster-like flowers that grow in clusters. Most commonly blue but can be pink or white. Terminal in clustered cymose heads; heads 1/4" diameter; Involucral bracts imbricated in several series. Lavendar, blue to pink, or white, tubular with 5 small lobes; pistils exerted, styles forked.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Type:
- Simple
- Leaf Arrangement:
- Opposite
- Leaf Shape:
- Cordate
- Deltoid
- Obtuse
- Ovate
- Leaf Margin:
- Crenate
- Hairs Present:
- Yes
- Leaf Description:
- Alternate, ovate to deltoid, pilose on both sides to slightly downy, obtuse, cordate, crenate.
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Stem:
- Stem Color:
- Green
- Red/Burgundy
- Stem Is Aromatic:
- No
- Stem Description:
- Semidecumbent, sometimes branched, green to reddish.
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Landscape:
- Landscape Location:
- Container
- Landscape Theme:
- Butterfly Garden
- Drought Tolerant Garden
- Pollinator Garden
- Attracts:
- Butterflies
- Pollinators
- Resistance To Challenges:
- Deer
- Drought
- Rabbits
- Problems:
- Weedy
