Poison hemlock
Conium maculatum · Apiaceae
The gardener's calendar
Ideal time to plant poison hemlock: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous
- Flowering
- Summer (June to August)
- Adult size
- 0.6 to 1.5 m in height
- Growth
- Fast
- Hardiness
- Hardy, down to -15 °C
- Origin
- Mediterranean basin and Western Europe
- Soil type
- All soils, very adaptive
Care
Light Exposure
Poison hemlock thrives in full sun or partial shade. It tolerates bright environments well and adapts to partial exposures. Choose a well-ventilated location to promote good growth.
Watering
Water regularly during dry periods, particularly in summer. This plant prefers fresh but well-drained soils. Reduce watering in autumn and winter when growth slows down.
Soil
Poison hemlock adapts to all soil types: clayey, chalky or acidic. It even tolerates moist and disturbed soils. Soil enriched with organic matter will promote better growth.
Fertilizing
Apply a balanced fertilizer in spring to stimulate vigorous growth of this plant. One annual application is generally sufficient. Avoid excess nitrogen, which would promote excessive foliage development.
Pruning and management
No real pruning is necessary. Remove withered or damaged stems as the season progresses. Since this plant is biennial or annual, it will self-seed naturally if conditions suit it.
Pests and diseases
Poison hemlock is rarely affected by serious diseases. Watch for aphids or scale insects, especially in conditions of excessive humidity. Good drainage and ventilation prevent most problems.
Did you know?
Poison hemlock is sadly famous for having been used in the death sentence of Greek philosopher Socrates in 399 BCE. Its toxic alkaloids marked the history of Western philosophy. This dangerous plant remains nonetheless common in Europe, often confused with other harmless umbellifers.
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.