Photo: Bernd Haynold, CC BY-SA 2.5 · source

Herb · Asteraceae

Arnica

Arnica montana

In other languages: Valkruid (Nederlands) · Arnica des montagnes (Français)

Arnica is a native perennial of the daisy family, growing in the mountains of Europe and, in the lowlands, on heaths and poor, acid grasslands. In Belgium it has become very rare and survives in only a few places in the Campine and the Ardennes. It forms a flat rosette of hairy, oval leaves, from which stems 20–40 cm tall rise in June–July, carrying large, orange-yellow, scented flower heads. Bees, bumblebees and butterflies love them. In the garden it is a challenge: it only succeeds on acid, poor, lime-free soil.

Caution: Poisonous if swallowed: do not eat any part of the plant or make tea from it. Keep children, cats and dogs away from the flowers and leaves. In sensitive people, contact can irritate the skin. Never pick or dig it up in the wild: it is rare and on the Red List.

Updated on 9 October 2026

Light
Full sun
warm and bright
Moisture
Normal
no wet feet
Legal basis
Sand
acid
Hardiness
Fully hardy
down to -30 °C
Size
0.4 m
tall, 0.2 m wide
Flowering
June–July

Key facts
Height	0.4 m
Native to Belgium	Yes
Good for bees, butterflies and birds	Yes, for bees and butterflies
Poisonous to people and pets	Yes, take care with children and pets
Flowering	June–July

Identify

Arnica: how do you recognise it?

Habit: Low rosette of leaves lying flat on the ground, with flowering stems 20–40 cm tall; it spreads slowly by creeping rhizomes.
Leaves: Oval, untoothed, 5–15 cm, slightly hairy and a little sticky, in a rosette; on the stem one or two pairs of smaller, opposite leaves.
Flower: One to three flower heads 5–8 cm across per stem, orange-yellow, with slightly notched ray florets; in June–July.
Scent: The whole plant, and especially the flower, has a spicy, aromatic smell.
Roots: A creeping rhizome that forms new rosettes; after a few years a small group develops.

Flowering: June–July · Plants: April–May

In your garden

Why grow it?

One of the loveliest native flowers: large, glowing orange-yellow flower heads in June–July.
A food source for bees, bumblebees and butterflies in a natural heathland garden.
Ideal for poor, acid sandy soil where few other flowers do well.
A low, compact plant that also fits a pot or raised bed.
Growing it helps keep a rare plant going, without taking it from the wild.

Arnica: where does it grow best?

Full sun; in shade it flowers little and soon disappears.
Acid, poor sandy soil without lime: as on a heath.
Moderately moist: the soil must not dry out, but must not stay wet either.
An open spot with no competition from grass or tall plants; plant 20–25 cm apart in a small group.

Light: Sun
Soil type: Sand
Acidity: Acid
Moisture: Normal
Size: 0.4 m tall, 0.2 m wide
Hardiness: Hardy (to -30 °C)

Goes well with

Heather: Its natural partner on acid, poor sandy soil, flowering in late summer.
Tormentil: A low, yellow-flowered plant of the same heathy grasslands.
Devil’s-bit scabious: Blue pompons in late summer for bees and butterflies, on the same poor soil.
Wavy hair-grass: A fine, low heathland grass that does not smother the rosettes.

Maintenance

Arnica: when and how to plant it?

Plant in April–May.

Plant in April–May, when the soil warms up and the rosettes start to grow.
On ordinary garden soil: make a bed or use a large pot with acid compost for heathers, mixed half and half with sand. Never use lime, compost or fertiliser.
Set the rosette at the same depth as it was in the pot: the crown must stay just above the soil.
Plant 20–25 cm apart, ideally in a group of three to five plants.
Water straight away, preferably with rainwater: tap water is limy in many areas.
Do not mulch with compost or bark; a thin layer of sand round the rosette helps keep slugs at bay.

Care

Water: Keep the soil lightly moist with rainwater, especially in a pot and in dry spells. Never let it dry out, but avoid wet feet.
Feeding: Never: fertiliser and compost make it decline and give grass and weeds the upper hand.
Weeding: Keep grass and weeds away from the rosettes; arnica does not tolerate competition.
Slugs: Protect young rosettes in particular in spring: slugs love the leaves.
Repotting: In a pot, repot every two to three years in April into fresh acid soil with sand.

Tip: Grow it in a pot or raised bed with acid soil and sand, and use only rainwater: on ordinary, limy or fertilised garden soil it soon disappears.

Arnica: when to prune it?

When: No pruning is needed. Just cut off the spent stems in July–August, unless you want seed.

How:

Cut spent flower stems back to just above the rosette.
Let a few flowers set seed if you want to collect it.
In autumn, carefully remove dead leaves so that rot does not set in at the crown.
Wear gloves if you have sensitive skin.

Caution: If you have sensitive skin, avoid handling the plant with bare hands: it can irritate the skin.

Pruning calendar and basic rules

Propagation

Division: In April, carefully lift a group and separate the rosettes, each with a piece of rhizome. Replant at once in acid, sandy soil.
Seed: Sow fresh, ripe seed in a pot of acid, sandy soil and leave it outside over winter; the cold helps the seed germinate. Seedlings grow slowly and flower only after two to three years.

Arnica: how does it get through the winter?

Hardy to −30 °C.

Very hardy, to about −30 °C: in Belgium no protection against cold is needed.
The plant largely dies back in autumn and shoots again in spring.
Winter wet is more dangerous than frost: make sure water drains away well, in a pot too.
Leave pots outside, raised on pot feet and slightly sheltered from persistent rain.

Diseases and pests

Slugs: Rosettes eaten or vanished in spring. Protect young plants, collect slugs in the evening and keep the surroundings open and dry.
Decline: Yellow leaves and few flowers, often caused by lime, fertiliser or soil that is too rich. Use acid, poor soil and rainwater.
Root rot: The rosette turns limp and brown, especially in a wet winter. Provide well-drained, sandy soil.
Being crowded out: Grass and weeds grow over the rosettes and the plant disappears. Weed regularly and never feed.

Through the year

March: New rosettes appear. Watch for slugs.
April: Plant. Divide old groups. Keep slugs away.
May: Plant. Weed out grass and weeds.
June: Flowering; bees and butterflies. Water with rainwater in dry spells.
July: Flowering. Cut off spent stems or let them set seed.
August: Collect ripe seed and sow it in a pot.
September: Weed round the rosettes.
October: The leaves die back. Carefully remove dead leaves.
November: Raise pots on pot feet against wet feet.

Use

Edible and useful

Not edible. Arnica is poisonous when taken internally: a tea or tincture can cause heart rhythm problems and severe stomach and gut upsets. Do not use it in cooking or make your own remedies to swallow; pharmacy ointments are for unbroken skin only. People allergic to the daisy family can react just from touching it. In the wild, arnica is rare and protected. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees: Nectar and pollen for honeybees and wild bees.
Butterflies: Nectar for butterflies.

You and this species

Did you know?

Unlike most members of the daisy family, its stem leaves grow in opposite pairs.
Fertilisers, acidification and the loss of heathland have caused a sharp decline in the Low Countries; it is a typical species of poor, heathy grassland.
Its Dutch name, valkruid, means ‘fall herb’, a reminder of its old folk use after a fall or a knock.

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