Cow Parsnip vs Nodding Onion - TreeTime.ca

Cow Parsnip vs Nodding Onion

Heracleum maximum

Allium cernuum

CUSTOM GROW

NOT AVAILABLE THIS SEASON - MIGHT RETURN

Cow Parsnip
Nodding Onion

Cow Parsnip is a native perennial wildflower known for its tall growth, very large leaves, and broad clusters of white flowers. The abundant blossoms provide nectar and pollen for a wide variety of pollinators, including bees and butterflies. Birds and small mammals feed on its seeds, while the foliage serves as a larval host for certain butterfly species.

Cow Parsnip is often among the first native perennials to establish in disturbed or open sites. It typically grows in moist meadows, along streambanks, forest edges, and roadsides. Although usually a short-lived perennial or biennial, it readily self-seeds and maintains strong populations where conditions are favorable.

Cow Parsnip is the only native Heracleum in North America and should not be confused with the highly invasive Giant Hogweed (H. mantegazzianum).

Note: The sap of the Cow Parsnip can cause phytodermatitis when exposed to ultraviolet light (sunlight). This can cause rashes or even burns. Care should be taken if pruning or handling this plant.

Nodding Onion is a native perennial wildflower known for its nodding clusters of flowers that range in color from white to pink to purple. The lightly scented blooms provide pollen and nectar for pollinators, especially bees, which can collect while hanging upside down, a capability most other insects lack.

The narrow, grass-like leaves of the Nodding Onion can be used as a seasoning in cooked dishes, though bulbs and raw leaves should not be eaten in large quantities. All parts of the plant have an onion-like aroma when bruised, which helps deter deer and rabbits. They can self-seed readily, so removing spent blooms helps manage their spread. Tolerant of a range of soils, including alkaline, it is well-suited for a variety of plantings, including pollinator gardens and naturalization projects.

Cow Parsnip Quick Facts

Nodding Onion Quick Facts

Zone: 2a
Zone: 3a
Height: 1.8 m (6 ft)
Height: 0.3 m (1.0 ft)
Spread: 1.2 m (4 ft)
Spread: 0.2 m (0.5 ft)
Light: partial shade, full sun
Light: partial shade, full sun
Moisture: normal, wet
Moisture: dry, normal
Growth rate: fast
Growth rate: fast
Life span: short
Life span: short
Growth form: upright
Growth form: upright to spreading, clump-forming
Spreading: seeds - low
Spreading: seeds - high
Maintenance: medium

Toxicity: sap causes skin irritation

Toxicity: raw leaves and bulbs can be midly toxic
Foliage: very large, palmate leaves
Foliage: smells of onion when crushed, edible
Flowers: large clusters of white flowers
Flowers: white, pink, or purple nodding clusters
Bloom time: spring to early summer
Bloom time: late spring to summer
Hybrid: no
Hybrid: no
Catkins: no
Catkins: no


Native to: AB, BC, SK, MB, ON, QC, NS, NB, NL, YT, NT, PE
Native to: AB, BC, SK, ON
Other Names: american cow parsnip, common cow parsnip
Other Names: ladys leek, nodding wild onion