Cow parsnip
Heracleum maximum · Apiaceae
The gardener's calendar
Ideal time to plant cow parsnip: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous
- Flowering
- June to August
- Adult size
- 1.5 to 2.5 m in height
- Growth
- Fast
- Hardiness
- Very hardy (down to -20 °C)
- Origin
- North America
- Soil type
- Moist, rich in organic matter
Care
Watering
Woolly hogweed loves consistently moist soil, especially during the growing period. Water regularly in summer, particularly during prolonged dry spells. In autumn and winter, gradually reduce water supply. Soil that dries out too much will slow its development.
Exposure
Plant woolly hogweed in full sun or partial shade. It tolerates partial shade well but will flower more abundantly in a sunny location. Protect it from strong winds that can damage its hollow stems.
Soil and potting mix
Prepare deep, moist soil enriched with organic matter. Adding compost or well-decomposed manure at planting time improves structure and water retention. Avoid overly compacted or heavy clay soils.
Fertilizer
Balanced fertilizer applied in spring is generally sufficient to support its vigorous growth. In poor soil, an annual addition of organic matter (rich mulch) effectively replaces chemical fertilizer.
Pruning and cutting
No structural pruning is necessary. Simply remove dried stems at the base in late autumn or early spring. If you want to limit seed production, cut off faded flower umbels before they mature.
Diseases and pests
Woolly hogweed is generally robust. Watch for aphids and whiteflies in summer, which can be treated with a water spray or natural insecticide. Stagnant excess moisture can encourage root rot; improve drainage if needed.
Did you know?
Woolly hogweed is a flagship plant in traditional North American phytotherapy: indigenous peoples used its roots for their diuretic and anti-inflammatory properties. Its scientific name Heracleum pays homage to Heracles (Hercules), referring to its herculean growth strength and imposing size.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
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Tips generated and checked by Viridia — adapt them to your local climate.