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Annual Biennial

Ageratum houstonianum 'Blue Horizon'
  • RHS AGM
  • RHS Plants for pollinators

Mexican paintbrush 'Blue Horizon'

'Blue Horizon' is a mound-forming annual with long-stemmed violet-blue flower-heads. Good for cutting

Size
Ultimate height
0.1–0.5 metres
Time to ultimate height
1 year
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Clay
Loam
Sand
Moisture
Moist but well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Blue Green
Autumn Blue Green
Winter
Position
  • Full sun
Aspect

South–facing or West–facing

Exposure
Sheltered
Hardiness
H2
Botanical details
Family
Asteraceae
Native to the UK
No
Foliage
Deciduous
Habit
Bushy
Genus

Ageratum can be annuals, perennials or shrubs, usually bushy in habit, with simple ovate leaves and small fluffy blue, pink or white flower-heads in summer and autumn

Name status

Accepted

How to grow

Cultivation

This genus is ideal edging for bedding schemes; bearing weather-resistant flowers on young plants. To prolong flowering, keep soil or growing media moist.

Propagation

Propagate by seed

Suggested planting locations and garden types
  • City and courtyard gardens
  • Patio and container plants
  • Cottage and informal garden
  • Flower borders and beds
  • Garden edging
Pruning

No pruning required

Pests

Generally pest free

Diseases

Generally disease free

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