Image for Red Alder

Red Alder

Scientific name

Alnus rubra


Red Alder is a fast growing deciduous tree species that typically grows between 12 and 15 m in height. The bark is smooth and light gray colored. The leaves are alternately arranged, dark green colored, oval shaped, and have coarsely toothed margins. The male catkins are long and drooping while the female catkins are short and upright. Both appear between March and April. The roots are useful for controlling erosion and stabilizing shorelines. Red Alder’s root system also contains nitrogen-fixing bacteria, converting atmospheric nitrogen into a usable form and increasing this nutrients availability in the soil, which can be beneficial for other nearby plant species.

Planting conditions

Red Alder grows best in moist to wet conditions with full or partial sun exposure. It prefers sand or loam soils but can grow in a variety of soil types. It can tolerate poor soil, steep slopes, drought, and periodically flooded areas. It is a costal tree and only appears near the Pacific Northwest. This tree can be naturally found in moist forests, around marshes and swamps, or along stream shorelines.


  • Plant height:
    • Any
    • Over 3m
  • Moisture level:
    • Dry
    • Normal
    • Moist
    • Wet
  • Light conditions:
    • Full sun
    • Partial sun
  • Soil type:
    • Sandy
    • Loamy
    • Clay
    • Rocky
  • pH:
    • Acidic
    • Normal
  • Depth:
    • Potted
    • Bareroot
  • Eco Zone:
    • 6a
    • 6b
    • 7a
    • 7b
    • 8a
    • 8b
  • Plant type:
    • Tree
  • Height:
    • 13m
  • Spread:
    • 3m