wetland shrub
Grey alder
Alnus incana
1 of 2Native to much of the USA and Canada
Labrador to Alaska, south to New Jersey, mountains of West Virginia, northeastern Illinois, northeastern Iowa, Minnesota, northeastern North Dakota and western mountains to New Mexico and central California
- Light Full sun to shade Sun tolerance
- Moisture Moist to wet Moisture preference
- Zones 2–8 Cold to heat range
- Bloom Mar–May Flowering time
- Height
- Life cycle Perennial Annual to perennial
In the garden
A wetland shrub for sun through shade and consistently moist to wet soil. Hardy in USDA zones 2–8.
Growing conditions
Light
Full sun Partial shade Full shade
Moisture
Dry Moist Wet
Hardiness zones
Find your zone:
Pollinators & wildlife
- Moths Fall Webworm Moth also Acronicta psi, Spotted Tussock Moth
- Bees Buff-tailed Bumble Bee
- Butterflies Limenitis arthemis arthemis
Butterflies that use this plant
Documented host and nectar records. Each links to a planting guide for that butterfly.
- Red-spotted purplenectar
Full plant details
Where it grows
- Habitat
- WetlandThe wild plant community it grows in.
- Native range
- Much of the USA and CanadaUnited States (32): AK, AZ, CA, CO, CT, IA, ID, IL, IN, MA, MD, ME, MI, MN, MT, ND, NH, NJ, NM, NV, NY, OH, OR, PA, RI, UT, VA, VT, WA, WI, WV, WY. Canada (12): AB, BC, MB, NB, NL, NS, NT, ON, PE, QC, SK, YT. Where it grows wild on its own, by state and province.
- Native distribution
- Labrador to Alaska, south to New Jersey, mountains of West Virginia, northeastern Illinois, northeastern Iowa, Minnesota, northeastern North Dakota and western mountains to New Mexico and central CaliforniaThe same native range, usually more exact than the state list, and often noting where it has spread beyond it.
Growing conditions
- Light
- Full sun to shadeHow much sun it takes, from full sun to full shade.
- Moisture
- Moist to wetThe soil dampness it prefers, from dry to wet.
- Hardiness zones
- USDA 2–8 · Canadian 1–8The cold-to-heat climate range it survives.
- Soil
- Wet soilsThe soils it grows in naturally.
- Soil texture
- Medium to heavy (loamy to clay)The soil grade it prefers, from sand to clay.
- Soil pH
- 5.0–7.0The acidity to alkalinity it tolerates (7 is neutral).
- Soil quality
- MediumHow rich a soil it needs. Many natives prefer lean soil and flop in rich beds.
- Water use
- HighHow thirsty it is, a rough guide to how often to water.
- Salinity tolerance
- NoneHow well it copes with salty soil, near roads or the coast.
- Lime (CaCO₃) tolerance
- LowHow well it copes with chalky, lime-rich soil.
Growth & form
- Spread
- ~16 ft (5 m)How wide one plant gets, a guide to spacing.
- Life cycle
- PerennialWhether it lives a single season (annual), two (biennial), or returns for years (perennial).
- Growth rate
- RapidA relative ranking versus other plants of the same type (USDA), not an absolute rate.
- Shape
- ErectIts overall silhouette.
- Root depth
- 24+ in (61+ cm)How far the roots reach, a guide to drought resilience and transplanting.
Flowers, foliage & fruit
- Type
- ShrubWhat kind of plant it is.
- Bloom
- Mar–MayWhen it flowers.
- Flower color
- Red, GreenThe bloom color, or colors.
- Toxicity
- None knownWhether any part is poisonous to people or pets.
Propagation & seed
- Cold stratification
- Required (cold, moist)Whether seed needs a cold, moist spell before it will germinate.
- Propagation
- Bare root, container, seedHow to start new plants.
- Seed
- ~1 million seeds per poundNotes on the seed and how to sow it.
- Seed spread rate
- SlowHow readily it self-sows. Slow or none means well-behaved, not a spreader.
- Seedling vigor
- LowHow strongly young seedlings establish.
- Vegetative spread
- SlowWhether it creeps outward or stays put in a clump.