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Blue Billygoatweed Ageratum houstonianum

Phonetic Spelling
a-ger-AE-tum ho-stone-ee-AE-num
Description

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: powdery mildew

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
Cultivars / Varieties:
  • 'Leilani Blue'
  • 'Neptune Blue'
  • 'Redtop'
  • 'Summer Stars'
  • 'True Blue'
Tags:
#white#butterflies#pink#sun#full sun#partial shade#annual#summer#blue#drought tolerant#summer annual#white flowers#container plant#wildlife plant#pink flowers#showy#blue flowers#cut flowers#rabbit resistant#cpp#bedding plant#summer flowers#deer resistant#aster#pollinator plant#fantz
 
Cultivars / Varieties:
  • 'Leilani Blue'
  • 'Neptune Blue'
  • 'Redtop'
  • 'Summer Stars'
  • 'True Blue'
Tags:
#white#butterflies#pink#sun#full sun#partial shade#annual#summer#blue#drought tolerant#summer annual#white flowers#container plant#wildlife plant#pink flowers#showy#blue flowers#cut flowers#rabbit resistant#cpp#bedding plant#summer flowers#deer resistant#aster#pollinator plant#fantz
  • 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, drought
    Dimensions:
    Height: 0 ft. 6 in. - 1 ft. 0 in.
    Width: 0 ft. 10 in. - 1 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Annual
    Leaf Characteristics:
    Deciduous
    Growth Rate:
    Medium
  • 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
  • Fruit:
    Fruit Type:
    Achene
    Fruit Description:
    Fruit is a cypsela which is a type of achene.
  • 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.
  • Leaves:
    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.
  • Stem:
    Stem Color:
    Green
    Red/Burgundy
    Stem Is Aromatic:
    No
    Stem Description:
    Semidecumbent, sometimes branched, green to reddish.
  • Landscape:
    Landscape Location:
    Container
    Landscape Theme:
    Butterfly Garden
    Drought Tolerant Garden
    Pollinator Garden
    Attracts:
    Butterflies
    Pollinators
    Resistance To Challenges:
    Deer
    Drought
    Rabbits
    Problems:
    Weedy