Thorn-apple

How to recognise it

Habit

Annual, almost hairless plant, 30–100 cm tall, sometimes up to 1.5 m, with forked branching stems and a broad, bushy shape.

Leaf

Large and oval, 8–20 cm, with a coarsely and irregularly toothed or lobed edge; dark green and unpleasant-smelling when bruised.

Flower

From July to October large white, sometimes pale purple, trumpet flowers 6–10 cm long, borne singly in the forks of the stems, with five pointed tips. They open in the evening, are fragrant and stay open only briefly.

Fruit

An upright, egg-shaped capsule 3–5 cm long, covered in stout spines, which splits into four valves and releases hundreds of black, kidney-shaped seeds.

Stem

Thick, round and smooth, green or tinged purple; plants with purple stems usually have pale purple flowers.

Confused with

Angel’s trumpet (Brugmansia) is a shrub with hanging flowers and smooth fruits. Other garden thorn-apples, such as Datura innoxia, have grey, downy leaves and nodding fruits. Young plants can come up among vegetables and be harvested by mistake: learn to recognise the coarsely toothed, unpleasant-smelling leaf.

Flowering: July–October · Pruning: August–October

Why grow it?

• Large, fragrant white trumpet flowers that open in the evening and attract moths such as hawk-moths.
• A striking, exotic-looking plant with spiny fruits: a fascinating species to get to know in a fenced-off, educational garden.
• A pioneer of disturbed, rich ground: it appears where the soil has just been disturbed and disappears again as the vegetation closes in.
• Important to recognise: it can turn up as a highly poisonous weed in the vegetable garden, in fields and under the bird feeder.
• A plant with a long cultural history that plays a part in stories, folk customs and the history of botany.

Thorn-apple: where does it grow best?

• In the wild: arable fields, especially maize and vegetable fields, waste ground, rough ground in ports and on industrial sites, riverbanks, compost heaps and tips.
• Full sun and a warm spot: in cool, wet summers it stays small or does not flower.
• Nutrient-rich, loose, disturbed soil; sand, loam or clay, normally moist to rather dry.
• In the garden it often appears by itself under the bird feeder, on the compost heap or in the vegetable patch. If you grow it on purpose, choose a spot children and pets cannot reach.

Goes well with

• Evening primrose: Yellow flowers that also open in the evening and attract moths.
• White campion: White flowers scented in the evening, for a moth garden.
• Honeysuckle: A climber strongly scented in the evening that attracts hawk-moths.
• Soapwort: Pink flowers scented in the evening that attract moths, in the same sunny spot.

Thorn-apple: when and how to plant it?

1. Think carefully first: only grow thorn-apple in a garden without small children or pets, or in a fenced-off corner.
2. Sow indoors in pots in April, or outdoors where it is to grow after mid-May once the soil is warm; the seed does not need a cold period. Cover it with 0.5–1 cm of soil.
3. Plant or thin to 50–60 cm apart: a single plant soon grows half a metre wide.
4. Wear gloves when sowing, transplanting and weeding, and wash your hands afterwards.
5. Water until the young plants are growing well; after that it manages without extra water in an ordinary summer.
6. Never take plants or seed from fields or the wild, and do not scatter seed outside your garden.

Care

Water

In a long dry spell, water at the base; otherwise it needs little.

Feeding

Not needed: on rich soil it grows big enough already.

Fruits

Cut off the spiny fruits with gloves on before they split open, if you do not want seedlings.

Seedlings

Weed out unwanted seedlings while young, wearing gloves, before they flower.

Clearing up

Pull the plant up after the first frost and put it in the general waste, not on the compost heap: the seed survives there easily.

Tip: If you see an unknown plant with coarsely toothed, foul-smelling leaves coming up under the bird feeder or in the vegetable garden, pull it up with gloves on before it flowers: thorn-apple seed is sometimes found in birdseed or in imported soil.

Pruning and mowing

Pruning months: August–October.

When: No pruning. In August–September cut off the fruits before they split open, and pull the plant up in October, after the first frost.

How:

• Wearing gloves, cut off the green, spiny fruits as soon as the flowers have faded.
• Put them in a bag and throw them in the general waste.
• After the first night frost, pull up the whole plant with its root.
• Never put plant waste carrying seed on the compost heap.

Caution: Always wear gloves and do not touch your eyes or mouth afterwards: the sap is poisonous and can dilate the pupil for hours if it gets into the eye.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow indoors in April or outdoors after mid-May, in a warm spot. The seed only germinates in warm weather and stays viable in the soil for many years.

Self-seeding

One plant produces thousands of seeds. They fall around the plant or travel with soil, compost, birdseed and crops; that is how it turns up in unexpected places.

Thorn-apple: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Annual: the plant dies at the first night frost and survives the winter only as seed.
• The split fruits sometimes stay on the dead stems into winter; clear them away, because the seed is poisonous too.
• The seed tolerates frost and lies in the soil for many years: after digging, plants can suddenly appear again.

Diseases and pests

• Toxicity: The main concern: children may put seeds or flowers in their mouths and pets may nibble the plant. Grow it fenced off or not at all, and clear away fruits and seed.
• Self-seeding: It self-seeds freely. Cut off the fruits before they split open and weed out seedlings while young.
• Unwanted in the vegetable garden: Seedlings among vegetables can be harvested by mistake. Weed them out as soon as you recognise them and check your harvest.
• Aphids and slugs: Young plants sometimes get aphids or slug damage. Natural enemies usually deal with the aphids; remove slugs in the evening.

Through the year

• April: Sow indoors in pots.
• May: After mid-May, sow or plant out. Weed out unwanted seedlings.
• June: Water in dry weather. Recognise and weed out seedlings in the vegetable garden.
• July: First flowers. Watch for moths in the evening.
• August: Full flower. Cut off fruits with gloves on.
• September: Flowering. Remove fruits before they split open.
• October: Last flowers. After the first frost, pull up the plant and put it in the general waste.

Did you know?

• The name jimsonweed comes from Jamestown in Virginia: according to an old account, soldiers there ate the plant in 1676 and behaved in a confused way for days.
• The seed can stay viable in the soil for decades; that is why the plant sometimes suddenly appears after earthworks in a spot where it had not been seen for years.
• The flowers open in the evening and are most fragrant then, which attracts moths; yet the plant can also pollinate itself.