Grey alder
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1Will it grow where I live?
Grey alder is hardy to zone 2 – that covers all of Central Europe and the British Isles, and every USDA zone from 2 upwards. It needs real winter cold and struggles in the mildest sites (zone 8 and warmer). It also needs warm summers – in Central Europe that means wine-growing regions, cities or a sheltered south-facing wall.
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Profile
- Family
- Betulaceae
- Habit
- Tree
- Height
- 18 m
- Spread
- 10 m
- Growth
- very fast
- Lifespan
- 80 years
- First yield
- after 5 years
- Hardiness
- zone 2–6
- Shade tolerance
- partial shade
- Soil
- Silt, Loam, Clay
- Soil moisture
- dry – near water
- pH
- 5.6 – 7.6
- Synonyms
- Betula alnus incana.
Uses
Other uses: This species fixes atmospheric nitrogen and is also tolerant of contaminated soils. It is suitable for land reclamation, especially on coal spoil heaps. It is an excellent pioneer tree species for reforesting wasteland, difficult sites etc. Through its rapid growth it quickly creates sheltered conditions that allow further, more permanent woodland trees to become established. In addition, bacteria on the roots fix atmospheric nitrogen. This not only enables the tree to grow well on nutrient-poor soils, but also makes nitrogen available to other plants nearby. Alders also have a dense leafy crown, whose leaf fall contributes to humus formation in the soil in autumn. Alder seedlings cannot compete well in the shade of woodlands, so this species gradually dies out as other tree species become established. Bark and fruits contain up to 20% tannins. The wood is light, soft, relatively elastic and easy to split. It is used for clogs, bowls, wood carvings etc. and is highly valued by joiners.
Growing
Prefers heavy soils and moist sites. Thrives on heavy clay soils. Tolerates drier soils than many other species in this genus. Tolerates very nutrient-poor sites. This species lives in symbiosis with certain soil micro-organisms. These form nodules on the roots of the plants and fix atmospheric nitrogen. Some of this nitrogen is used by the growing plant, some is available to neighbouring plants.
Propagation
Samen – am besten im Frühbeet aussäen, sobald sie reif sind, und nur leicht mit Erde bedecken. Im Frühjahr ausgesäte Samen keimen ebenfalls gut, solange sie nicht bedeckt werden. Die Keimung erfolgt im Frühjahr mit steigenden Temperaturen. Sobald die Sämlinge groß genug sind, werden sie in einzelne Töpfe pikiert. Bei ausreichendem Wachstum können sie im Sommer an ihren endgültigen Standort gepflanzt werden. Andernfalls bleiben sie in Töpfen im Freien und werden im Frühjahr ausgepflanzt. Wenn Sie genügend Samen haben, können Sie diese im Frühjahr dünn in ein Freilandbeet aussäen. Die Sämlinge können entweder im Herbst/Winter an ihren endgültigen Standort gepflanzt oder im Beet noch eine weitere Saison weiterwachsen gelassen werden. Stecklinge von ausgewachsenem Holz, die im Herbst nach dem Laubfall im Freien in sandigen Boden geschnitten werden, eignen sich ebenfalls zur Vermehrung.
Origin & habitat
Europe. Introduced to Britain.
Mountains, particularly on poor soils.
Frequently asked questions
Grey alder: how big does it get?
Grey alder (Alnus incana) grows as a Tree and reaches roughly 18 m in height when mature, with a spread of about 10 m. Growth is very fast.
Grey alder: what site does it need?
Grey alder tolerates partial shade. Suitable soils are Silt, Loam, Clay. Soil moisture should be in the range dry – near water. The pH may lie between 5.6 and 7.6.
Grey alder: is it hardy?
Grey alder is listed as hardy in zone 2–6 and survives normal winters outdoors there.
Grey alder: will it grow in Central Europe?
Grey alder is hardy to zone 2 – that covers all of Central Europe and the British Isles, and every USDA zone from 2 upwards. It needs real winter cold and struggles in the mildest sites (zone 8 and warmer). It also needs warm summers – in Central Europe that means wine-growing regions, cities or a sheltered south-facing wall.
Grey alder: is it poisonous?
Individual parts of Grey alder are noted as mildly problematic — the plant does not count as poisonous. With wild plants, never rely on a database alone, only on a confident identification.
Grey alder: what is it used for?
Rated on a scale up to 10: Edible 1/10, Medicinal 5/10, Other uses 1/10.
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