How to Grow Helianthemum
Helianthemum nummularium
Helianthemum is a low-growing evergreen sub-shrub that smothers itself in papery flowers from May to July. It thrives in full sun and poor, sharply drained soil — ideal for rockeries, gravel gardens, and wall tops. The single most important task is trimming hard after flowering to keep plants compact and long-lived. Extremely hardy and drought-tolerant once established.
Yearly Lifecycle
Care Essentials
Rarely needed. Helianthemum thrives in poor, well-drained soil. A light feed after the post-flowering trim is sufficient if growth seems weak.
Watch For
- Root rot in waterlogged soil
- Powdery mildew in humid conditions
- Dieback from hard frost on young plants
Companions
Aubrieta, Thyme, Dianthus, Lavender
Care Requirements
Light
Full sun essential
Demands full sun and hot, dry positions. Will not flower well or survive long in shade. Perfect for south-facing rockeries, gravel gardens, and wall tops.
Watering
Drought tolerant, hates wet feet
Extremely drought-tolerant once established. Do not water unless newly planted. Waterlogged soil kills helianthemum faster than cold. Excellent drainage is critical.
Fertilizing
Do not feed on normal soil
Thrives in poor, well-drained soil. Avoid fertilising in normal garden soil as rich conditions produce soft growth prone to winter damage and reduce flowering.
Pruning
Hard trim immediately after flowering
The single most important task. Shear back by one-third to one-half immediately after the main flush finishes. Without this, plants become woody and bare in the centre within 2-3 years.
Growing Tips
Trim hard after flowering
The single most important task for helianthemum. Shear back by one-third to one-half immediately after the main flush finishes. Without this, plants become woody and bare in the centre within 2-3 years.
Perfect drainage is essential
Helianthemum will tolerate extreme cold and drought but cannot survive waterlogged soil. Add grit to heavy soils at planting time, or grow in raised beds and rockeries where drainage is naturally sharp.
No feeding on rich soil
Avoid fertilising helianthemum in normal garden soil. Rich conditions produce lush soft growth that is prone to winter damage and reduces flowering. Poor soil produces the best displays.
