tree

Black alder

Alnus glutinosa

Updated 4 Aug 2026 · AI-parsed entry

Black alder (Alnus glutinosa) — a tree, for Full sun, High water.

What it needs & gives back

↓ Needs

Lightfull sun to partial shade
Watermedium to high

↑ Gives back

Mulch_biomasshigh
Shademoderate to dense

Through the year

Through the year

JFMAMJJASOND
emergenceBud break and leaf emergence typically occur after the last spring frost and when air temperatures consistently rise above 5°C.
floweringFlowering occurs in early spring, usually in March, as days lengthen.
fruitingFruits (strobiles) develop over the summer, maturing approximately 5 months after flowering.
senescenceLeaves begin to senesce and drop with the first autumn frosts and shortening day lengths.
dormancyEnters dormancy shortly after leaf drop, lasting through winter until spring.

Soil interactions

Drainagemoist to wet
Nitrogen fixingYes
MycorrhizalYes
Accumulatesnitrogen, calcium, magnesium
Soil textureloam, clay, sandy_loam
Organic matterHigh
Compaction toleranceMedium

Propagation

Methodsseed, cuttings
Difficulty2 / 5
Establishes in~2 yr
Stratificationrequires cold stratification
Self-seedingModerate
Divisionspring

Wildlife & pests

Attractspollinators, birds, wildlife
Can host pestsaphids, leaf miners
Can host diseasesphytophthora root rot, alder canker