Red Alder

Red alder (Alnus rubra)
Alnus rubra

Red alder (Alnus rubra) is a fast-growing deciduous tree that does well in open areas and along streams. This slender, medium-sized tree can grow 5′ or more a year for the first few years, and generally grows to 40-50 feet tall, sometimes reaching as high as 80 feet.

Red alder blooms in March, putting out long, rounded, dangling clusters of reddish-orange flowers called catkins. Leaves turn a slight golden color in the autumn. In the open, alder crowns form a lovely rounded shape with spreading branches.

This tree plays many roles in forested landscapes. Deer and elk browse on the leaves, buds, and twigs. The seeds are important winter food for birds such as redpoll, siskins, goldfinches, and others. Red alder provides food for the young of swallowtail and mourning cloak butterflies, and stands of this tree provide shade for a variety of forest understory plants such as osoberry, vine maple, and sword ferns.

This tree does best in sun to part shade with moist soils. Plant it for fast-growing shade and screening.

  • Light Requirements: Full Sun, Part Shade
  • Water Requirements: Moist
  • Ease of Growing: Easy to grow
  • Growth Rate: Moderate
  • Spreads: No
  • Wildlife Support: Pollinators, Pest-eating Insects, Birds or Mammals
  • Fire-resistant: Yes
  • Edible: No
  • Mature Height: 40-50ft
  • Mature Width:40-50ft