Red Alder (Alnus rubra)

Red Alder

Alnus rubra

Its peeling bark carries earthy warmth, a hardy native shade tree. Deciduous hardwood tree; common name: Red Alder.

Full sun
1–2/week
Moderate
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Plant Needs

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Sunlight Full sun to partial shade; tolerates open forest understory conditions and brief periods of dense shade
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Watering Prefers moist, well-drained soil; tolerant of occasional seasonal flooding but avoids prolonged waterlogging
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Temperature Hardy to cold winter temperatures; withstands mild summer heat up to 30°C
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Characteristics

  • Leaf: Oval to obovate, serrated margins, dark green upper surface, paler underside with fine hairs
  • Flower: Monoecious; male catkins are long, drooping; female catkins are small, upright
  • Stem/Bark: Young bark is smooth, gray-green; mature bark peels in papery reddish-brown strips
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Care Guide

Watering

Keep soil consistently moist during active growth periods

Fertilization

Apply balanced slow-release fertilizer once at bud break. Use low-nitrogen feed to prevent excessive foliage growth that weakens branch structure

Composted banana peel tea:Compost banana peels fully to break down sugars, dilute 1:20 with water for root drench; avoid raw peels to prevent pest infestations
Pruning
  • Remove dead or damaged branches in late winter to reduce disease risk
  • Thin crowded inner branches to improve airflow and light penetration
  • Shape young trees to establish a strong central leader for upright growth
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: Non-toxic to cats; no known toxic components

Humans: Non-toxic to humans; no reported adverse health effects from ingestion or contact

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Garden Uses & Culture

Culture: N/A

Usage: Used for reforestation, firewood, and woodworking; nitrogen-fixing root nodules improve soil fertility for companion plants