Alder
Alnus species (BETULACEAE)
Planting and Growing Alder Trees
You’ll find everything you need to know to plant and grow alder trees in the accompanying table’s tabs:
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- Foliage, cones, and seeds of alder trees
- Growing conditions for alder
- When to plant alder
- How to plant alder
- How to prune alder
- Watering, fertilizing, and care of alder
- Landscape uses of alder
- Pest and disease control for alder
Growing Alder Trees
About 30 species of fast-growing, upright, open, deciduous trees, usually 60–80 ft. (18–24 m) tall, with shiny, deep green, heart-shaped or oval, finely toothed leaves, to 4 in. (10 cm) long, turning yellow in autumn.
Cultivated species include Italian alder, Alnus cordata; American green alder; Alnus crispa; black alder, Alnus glutinosa; and white alder, Alnus rhombifolia. Dwarf species and cultivars are available.
Alder Planting and Care Guide
Catkins, Cones, and Seeds
Willowlike catkins, to 3 in. (75 mm) long, in spring before leaves emerge, with brown, clustered cones, 1/2–1 in. (12–25 mm) long in autumn.
Best Climates
U.S.D.A. Plant Hardiness Zones 4–10, depending on species.
Soil Type and Fertility
Moist, well-drained soil. Fertility: Average. 5.5–6.5 pH.
Where and How to Plant
Full sun to full shade. Space 15–20 ft. (4.5–6 m) apart. Transplant in spring.
Proper Care
Easy. Keep soil evenly moist. Prune to thin. Propagate by cuttings, seed.
About This Species
Good choice for margins, moist areas, understory in landscapes and water features. Very invasive. Shallow rooted. Borer, tent-caterpillar larvae, leaf miner and fungal disease susceptible.