Vibrant, fresh green leaves in early spring, then a red-coloured timber so resistant to decay that Venice used it for pilings: alder (Alnus) is the tree for ground other species refuse. Give it damp, even flooded soil and it will purify it, hold a riverbank against erosion and reach 60 feet with little attention.
| Name | Alnus |
|---|---|
| Family | Betulaceae |
| Type | tree |
| Height | 30 to 60 feet (10 to 18 meters) |
| Exposure | south, sunny |
| Soil | regular |
| Foliage | deciduous |
| Feature | hardy |
A very easy tree to care for, alder asks for little attention once settled in.
Planting an alder is best done in fall, as this promotes rooting before winter. You’ll see that it helps the tree have a smoother, healthier take-off in spring. But if you’ve bought your sapling in containers, you have a bit more flexibility: you can plant in spring or summer, as long as you avoid heatwaves.
Planting alder is a smart choice for poor soils, as it adjusts perfectly.
Alnus cordata or Corsican alder stands strong against early fall weather, usually persisting until November. Corsican alder grows faster than its peers.
Alnus glutinosa, or common alder, boasts a better hardiness and shows vibrant, fresh green colors in early spring.
White alder, or Alnus incana, adapts brilliantly to poor soils and mountainous regions due to its impressive resilience.
The three alders most often offered differ less in looks than in what they will put up with. This table lines up what each one is known for and the conditions it handles best.
| Species | Common name | Notable feature | Suited to |
|---|---|---|---|
| Alnus cordata | Corsican alder | Grows faster than its peers | Late-season interest: stands up to early autumn weather and persists into late autumn |
| Alnus glutinosa | Common alder | Vibrant, fresh green colours in early spring | Colder gardens: the best hardiness of the three |
| Alnus incana | White alder | Impressive resilience | Poor soils and mountainous regions |
Whichever you choose, alder asks for little attention once it has settled in.
Much like willow, alder thrives in moist lands. It helps purify soils and thus suits flooded areas exceptionally well.
Alder, soaring up to 65+ feet high (20 meters), offers red-colored wood. This wood is a favorite for pier piles thanks to its resistance to decay. Venice used it for pilings. Alder, as a live tree, also serves to strengthen riverbanks and protect them from erosion.
If pollen is something that often makes you sneeze, watch out! Alder can be a problematic allergen for some persons.
