How to Grow Arnica
Arnica montana
Arnica is a beautiful but demanding alpine perennial that thrives only when its specific needs are met. The non-negotiables are acidic soil (pH 5–6.5), sharp drainage, and low fertility — it cannot tolerate the rich, moist, neutral soils typical of UK gardens. Grow in a raised bed or rockery with gritty, acidic compost. Do not feed. Remove spent flowers to encourage repeat blooming. Divide clumps every 2–3 years to maintain vigour.
Yearly Lifecycle
Care Essentials
Do not feed. Arnica is native to nutrient-poor alpine meadows — fertiliser encourages lush vegetative growth at the expense of flowers and can kill the plant.
Watch For
- Slugs and snails (especially on young growth)
- Root rot in poorly drained soil
- Powdery mildew in dry summers
Companions
Heather, Wild thyme, Alpine strawberry
Pet Safety
Care Requirements
Light
Full sun
Needs full sun. Native to open alpine meadows; will not flower well in shade. At least 6 hours of direct sunlight daily.
Watering
Low; sharp drainage essential — never waterlogged
Water sparingly. Arnica hates waterlogged or constantly moist soil. Excellent drainage is the single most important requirement. In containers, ensure drainage holes are clear at all times.
Fertilizing
None — nutrient-poor soil is essential
Never fertilise. Arnica is adapted to nutrient-poor alpine meadows; any added fertility weakens the plant, causes excessive leafy growth, and reduces flowering.
Pruning
Deadhead after flowering; cut back in autumn
Remove spent flower heads to encourage a second flush. Cut all growth to ground level in autumn after natural die-back.
Spacing
30–45 cm apart
Space 35 cm apart in rockeries or raised beds. Good spacing improves air circulation and reduces mildew risk.
Spacing & Planting
| Plant spacing | 35 cm |
| Row spacing | 45 cm |
| Mature height | 60 cm |
| Mature spread | 30 cm |
