Helianthemum
Helianthemum nummularium
Spreads wider than it stands, hugging hot dry ground — though a hard frost can cut young plants back.
- Type
- Shrub · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Flower color
- Yellow
- Sunlight
- Full sun
- Feeding
- Rose & flower
- Frost tolerant
- Yes
- Flowering
- May
- Mar–May Spring Growth
- May–Jul Flowering
- Jul–Dec Growing
- Jan–Mar Growing
- Plant spacing
- 17.7 in
- In-row spacing
- 17.7 in
- Between rows
- 22 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, with a taproot it keeps
- Working depth
- 24 in–5 ft
- Can reach
- 10 ft down where the soil allows
- Spread
- 2–3.5 ft across, about 1.5–2.5× the width of the plant
It anchors downwards as well as sideways, which is what lets it stand in a gale and what makes it hate being moved. Plant it small: past a few years in the ground a taprooted tree transplants badly, and often not at all.
The habit is Helianthemum’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Powdery mildew Powdery mildew through humid spells
- Root & crown rot Root rot in waterlogged ground
- Dieback on young plants after hard frost
Aubrieta, Thyme, Dianthus, Lavender
Shrubs, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com