Italian Alder
Alnus cordata · Betulaceae
📷 The original uploader was MPF at English Wikipedia. · CC BY-SA 3.0
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around italian alder and prepare for winter.
ID card
- Family
- Betulaceae
- Type
- Deciduous tree
- Mature height
- Up to 20 m
- Foliage
- Deciduous, heart-shaped bright green leaves
- Flowering
- March to April, discreet catkins
- Growth
- Fast
- Hardiness
- Very hardy (down to -20 °C)
- Origin
- Italy (Corsica and Sardinia)
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability high.
Expert tips
The key tip
Black alder thrives in moist, loose soils, which it naturally improves (nitrogen fixation). Excellent in poorly drained areas or at the water's edge.
The common mistake
Planting it in dry, compact soil: it slows down significantly and remains weak.
The pro's trick
Sow dry catkins directly in February: they germinate abundantly.
Care
Exposure
Cordate alder prefers a location in full sun or partial shade. It tolerates well-lit and sunny spots that promote vigorous growth. Avoid overly shaded areas that would slow its development.
Watering
This tree enjoys fresh to moist soils and requires regular watering, especially during dry periods and when young. It adapts well to waterside locations and slightly waterlogged environments. Reduce watering once it's well established.
Soil and terrain
Cordate alder grows in various soils, preferring fresh, slightly acidic to neutral, well-structured terrain. It also tolerates moderate chalky soils. Good drainage is desirable even though it withstands prolonged moisture.
Pruning and shaping
Little intervention is needed for this vigorous tree. Prune lightly in late winter or autumn to remove dead or poorly oriented branches. Encourage a natural, airy shape for the tree's well-being.
Fertilizer
Fertilizer is generally not essential for cordate alder, which naturally benefits from a symbiosis with nitrogen-fixing bacteria. A mulch rich in organic matter is sufficient to maintain soil fertility.
Health and pests
Cordate alder is robust and rarely suffers from serious diseases. Occasionally watch for aphids and borers on young shoots. Good hygiene and regular aeration prevent most fungal problems.
Did you know?
Cordate alder is one of the rare alder species native to the Mediterranean basin, endemic to Corsica and Sardinia. Its roots form a remarkable symbiosis with Frankia bacteria that fix atmospheric nitrogen, making it a valuable tree for naturally enriching poor soils without requiring chemical fertilizer.
Where to buy it
Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.
Add this plant to my garden →Plants from the same family
- Silver birchBetula pendula
- Grey alderAlnus incana
- Dwarf birchBetula nana
- European Hop-hornbeamOstrya carpinifolia
- Turkish hazelCorylus colurna
- River birchBetula nigra
Tips generated and checked by Viridia — adapt them to your local climate.