It is best to wear gloves when handling it to avoid skin irritation.

Does it come back every year?

It is typically a biennial, meaning it grows leaves the first year and flowers the second.

Plant guide

Black henbane.

Hyoscyamus niger

Pronounced hy-os-SY-a-mus NY-jer

Also known as Black Henbane, Common Henbane, Henbane, Hog's-bean

Black henbane is a fascinating, ancient plant that has been used in folk medicine for centuries. It is a biennial herb that produces striking, funnel shaped flowers with dark purple veins. Please handle this plant with extreme caution as it is highly toxic if ingested.

Another photo of Black henbane — Photo by Christina s.l. (CC BY) via iNaturalist

At a glance

Care level: Moderate
Plant type: Herbaceous biennial
Light: Full sun to partial shade
Indoor light: Direct sun
Water: Every 5 to 10 days
Mature size: 3 feet
Growth rate: Medium
Hardiness: USDA 4 to 8
Bloom time: Late spring to summer

Care

Let the top inch of soil dry out between waterings and avoid soggy conditions to prevent root rot. Watch for wilting or yellowing leaves which often signal issues with moisture levels. Always wear gloves when handling this plant to avoid skin irritation from its oils.

Watering: Water when the top inch of soil feels dry to the touch.
Feeding: Apply a balanced liquid fertilizer once a month during the active growing season.
Pruning: Remove dead or damaged foliage to keep the plant tidy and encourage healthy growth.
Repotting: Repot only if the plant becomes root bound or needs a larger container for stability.
Soil: Well draining sandy or loamy soil
Soil pH: 6.0 to 7.5
Temperature: -20 to 30°C
Humidity: 40 to 70%

Safety

People: The plant contains tropane alkaloids like hyoscyamine and scopolamine that cause severe poisoning, hallucinations, and heart failure.
Pets: This plant is extremely toxic to cats and dogs if ingested and can cause severe illness or death.
Children: This plant is extremely dangerous to children and pets, so it should never be planted in areas accessible to them.
Contact allergens: Touching the foliage can cause skin irritation or dermatitis in sensitive individuals.
Airborne allergens: The pollen may cause mild respiratory irritation for those with severe allergies.
Edibility: Every part of this plant is highly toxic and potentially fatal if ingested.

How to identify it

Funnel shaped yellow flowers
Distinctive dark purple veining
Sticky glandular hairs on foliage
Foul smelling leaves
Large lobed basal leaves

Height: 0.3 to 1m
Spread: 0.3 to 0.6m
Leaves: gray-green, deciduous
Flowers: yellow, purple, 2 to 3cm
Fruit: brown, Late summer

Problems to watch for

Flea beetles · Small beetles that chew tiny holes in the leaves.
Powdery mildew · A fungal growth that appears as white dust on the foliage.

By symptom

Plant problems by symptom

Check your black henbane from a photo

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Growing it

Propagation: seed
When to plant: spring, autumn

Because of its toxicity, it is best kept in a dedicated botanical collection rather than a mixed garden bed.

Grows well with

Common Mallow · It shares similar soil preferences in disturbed areas.

Similar species

Belladonna · Both are toxic members of the Solanaceae family.

Science

Family: Solanaceae
Genus: Hyoscyamus
Order: Solanales
Class: Magnoliopsida
Native range: Europe, North Africa, and parts of Asia.
Conservation: It is considered a weed in many regions and is not of conservation concern.

It thrives in nitrogen-rich, disturbed soils where it can outcompete other plants.

Value to wildlife: nectar source
Pollinators: bees, beetles
Uses: historical medicinal interest, botanical curiosity

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 7/9
Light: 7/9
Temperature: 5/9
Moisture: 4/9
Nutrients: 8/9

Taxonomy resolved against GBIF.

Questions people ask

Is it safe to touch?: It is best to wear gloves when handling it to avoid skin irritation.
Does it come back every year?: It is typically a biennial, meaning it grows leaves the first year and flowers the second.

Where the name comes from

The name Hyoscyamus comes from the Greek words for hog and bean, while niger refers to the dark color of the flowers.

Good to know

It is a member of the nightshade family.
The plant has a distinct, unpleasant odor.
It often grows in disturbed soils near old ruins or roadsides.
Historically, it was used as an anesthetic.

Also in

Plants toxic to cats and dogs

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.