European alder
Alnus glutinosa · Betulaceae
European alder (Alnus glutinosa) is a perennial tree in the Betulaceae family. It is introduced to North America rather than native. USDA records it as hardy in zone 5 and warmer, down to about -18°F.
⚠ Invasive or noxious status. USDA lists this plant with an invasive or noxious weed status somewhere in its range. Check your state's noxious weed list before planting it — in some states it is illegal to sell or plant.
Both flags are quoted from USDA PLANTS, not inferred.
At a glance
| Type | tree USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | introduced USDA |
| Mature height | 45 ft USDA |
| Light | part-shade USDA |
| Water need | medium USDA |
| Growth rate | rapid USDA |
| Soil pH | 4.4–7.2 USDA |
| Bloom | April–May USDA |
| Flower color | Purple USDA |
| Hardiness zones | 5 and warmer USDA |
| Guild layer | canopy Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It grows in partial shade. USDA rates it as having moderate water needs. It is recorded on soils from pH 4.4 to 7.2 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 5; USDA publishes no warm-end limit, so gardeners in warmer zones should check local heat tolerance separately.
Size and growth
At maturity it reaches about 45 ft, making it a substantial woody plant. It grows quickly, which matters when you are timing a planting around the layers above it.
Bloom period
USDA records a bloom period of April through May. The flower color USDA records is purple. Bloom timing is how the Guild Builder overlaps flowering across a planting so something is in flower for as much of the season as possible.
Bloom period is a claim about when this plant flowers. It is deliberately not a pollinator rating — no dataset we trust publishes one, so we do not make that claim. See Data & sources.
Role in a guild
Canopy. In a layered planting this is the tallest layer of a planting — it sets the light budget everything beneath it lives on. We derive the layer from the plant's growth habit and mature height using a fixed rule, so the same inputs always produce the same layer.
Tags
Related plants
Others in Alnus
- gray alder Alnus incana
- speckled alder Alnus incana
- thinleaf alder Alnus incana
- seaside alder Alnus maritima
Similar role and hardiness
- tree of heaven Ailanthus altissima
- water hickory Carya aquatica
- southern catalpa Catalpa bignonioides
- Chinese chestnut Castanea mollissima
- tuliptree Liriodendron tulipifera
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol ALGL2, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
bloom_end— quoted from USDA PLANTSbloom_start— quoted from USDA PLANTScommercial_availability— quoted from USDA PLANTSduration— quoted from USDA PLANTSflower_color— quoted from USDA PLANTSgrowth_habit— quoted from USDA PLANTSgrowth_rate— quoted from USDA PLANTSguild_role— derived by rule from USDA columnsinvasive_caution— quoted from USDA PLANTSmature_height_ft— quoted from USDA PLANTSmoisture— quoted from USDA PLANTSnative_status— quoted from USDA PLANTSnitrogen_fixer— quoted from USDA PLANTSpet_safe— quoted from USDA PLANTSph_max— quoted from USDA PLANTSph_min— quoted from USDA PLANTSshade_tolerance— quoted from USDA PLANTStemperature_min_f— quoted from USDA PLANTSzone_min— quoted from USDA PLANTS
Read our full data sources and methodology.
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