Red alder

Alnus rubra | Also known as: Oregon alder, Western alder Alnus oregona | Rating: 0 votes | Print / Pdf

The red alder from the land of the red Indian.

Alnus rubra or red alder is native to North America. It's one of the tallest alders in the world reaching a height of up to 30m, so you don't want to plant this one in your garden, especially as it's quite fast growing. It's called the red alder, as when the bark gets scuffed, it develops a rust red colouring. It has mottled grey bark that is smooth in texture. The leaves are oval with a pointed tip, and have a shallow toothed edge and furrowed veins. You can spot a red alder by looking at the leaves closely. The red alder has leaves that curl back underneath at the edges.

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Plant
Known dangers?
  • no
Height [m]
  • 25
Spread [m]
  • 10
Dominant flower colour
  • Yellow
Flower Fragrance
  • No, neutral please
Flowering seasons
  • Early spring
Foliage in spring
  • Green
Foliage in summer
  • Green
Foliage in Autumn
  • Green
Propagation methods
  • seed
  • budding
  • Hardwood cuttings
Growth habit
  • Conical
  • Tapering
Environment
Acidity
  • Acidic
  • Neutral
  • Alkaline
Hardiness zone
  • Z4-7
Heat zone
  • H7-1
Winter temperatures [°C]
  • -34 - -12
Heat days
  • 0 - 90
Moisture
  • well-drained
  • well-drained but frequently watered
  • boggy
Soil type
  • Clay
  • chalky
  • loams
Sun requirements
  • Full sun
  • Partial shade
Exposure
  • Exposed
  • Sheltered
Usage
Standard category
  • Trees & shrubs
  • Trees
Grown for
  • Ornamental Foliage
Creative category
  • For Beginners
  • Bonsai
  • Pond plants
Garden type
  • Bog garden
  • Park
  • Pond
Garden spaces
  • Windbreak
Gardening expertise
  • beginner
Time to reach full size
  • 30 years or longer