Green Alder vs American Sweet Flag - TreeTime.ca

Green Alder vs American Sweet Flag

Alnus alnobetula subsp. crispa

Acorus americanus

COMING SOON

(new stock expected: fall of 2025)

CUSTOM GROW

Green Alder
American Sweet Flag

Green Alder is a cold hardy, native shrub. It is often planted on infertile sites so it can fix nitrogen from the air and improve the soil quality.

Green Alder is known for its smooth grey bark and attractive shiny green leaves; it is commonly used in reclamation.

American Sweet Flag is a native perennial wetland plant found along shorelines, streams, wet meadows, and marshes. Its extensive rhizome system allows it to spread and stabilise soil, helping maintain the edges of ponds and streams. This dense growth provides cover for small animals and supports overall wetland biodiversity, while the rhizomes and seeds serve as food for small mammals and waterfowl. Cold-hardy and resilient, it is well-suited for ecological restoration, riparian plantings, erosion control, and naturalization projects.

The plant grows in dense clumps with tall, sword-shaped leaves that release a citrus-like scent when bruised. The rhizomes are aromatic, with a spicy, cinnamon-like fragrance that has been used in perfumery and flavouring. In early summer, American Sweet Flag produces a distinctive floral spike (spadix), adding visual interest to wetland plantings.

Green Alder Quick Facts

American Sweet Flag Quick Facts

Zone: 1a
Zone: 3a
Height: 7 m (23 ft)
Height: 0.9 m (3 ft)
Spread: 3 m (10 ft)
Spread: 0.6 m (2.0 ft)
Light: any
Light: partial shade, full sun
Moisture: any
Moisture: wet
Growth rate: fast
Growth rate: fast
Life span: short
Life span: short
Growth form: upright, colony-forming
Spreading: rhizomes - high
Suckering: high


Foliage: fragrant
Flowers: yellow floral spike
Bloom time: spring to summer
Hybrid: no
Hybrid: no
Catkins: yes
Catkins: no

In row spacing: 0.9 m (3 ft)

Between row spacing: 5 m (16 ft)
Native to: AB, SK, MB, ON, NS, NB, NL, YT
Native to: AB, BC, SK, MB, ON, QC, NS, NB, NL, NT, PE
Other Names: american green alder
Other Names: american sweetflag