Common Cowparsnip
Heracleum maximum
- Native to:
- Aleutian Is., Canada, Japan, Kuril Is., Labrador, Prince Edward I., Russia, United States
miketilley (www.inaturalist.org)
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Apiaceae
- Genus:
- Heracleum
- Species:
- Heracleum maximum
- USDA Symbol:
- HEMA80
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Forb/herb
- Height:
- 300 cm
- Light Requirements:
- Shade
- Drought Tolerance:
- Low
- Bloom Months:
- may,jun,jul,aug
- Bloom Colors:
- white
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
- Caterpillars:
- ★★☆☆☆ Recorded caterpillar host plant (HOSTS Database)
Host Plant for Caterpillars
Reported Fauna Sightings
Garden & Ecology Notes
- Wildlife Value:
- bees, butterflies, flies, beetles, birds
- Fragrant:
- Yes
Soil Requirements
- Soil Type:
- rich, moist, well-drained loamy soil
- pH:
- 5.5 - 7.5 (slightly acidic to neutral)
- Drainage:
- tolerates poor drainage
- Moisture:
- consistently moist
- Notes:
- Thrives in riparian zones and wet meadows.
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 60–90 days
- Germination Time:
- 14–60 days
- Notes:
- Seeds require cold stratification and may germinate erratically over several weeks. Light may improve germination rates.
The above propagation data sourced from Claude AI
Pre-treatment: Seal the seeds in a container with an equal mix of seeds with perlite or vermiculite. Add just enough water to barely saturate the mixture and store in a refrigerator for at least 2 months. Alternatively, a 72 hour water soak of fresh seeds can be used, changing the water daily. Seeds should then be placed into a 100 day cold, moist stratification in a ventilated container under refrigeration at 1 to 3C.
Establishment: Seeds may not germinate in the first year and may require temperatures of 22C or above during the day and 13C to 16C at night in early June in the outdoor nursery. Transplant survival averages 50%. Conflicting information exists regarding the optimal stratification period, with recommendations ranging from 2 weeks to 2-3 months.
Source: npn.rngr.net
ORGHPS Germination Guide: Expose to fluctuating outdoor winter temps incl. freezing for 3 months. Increase light/temp in spring.