Rock soapwort Saponaria ocymoides
Rock soapwort (Saponaria ocymoides) is an evergreen perennial flowering plant in the Caryophyllaceae family, native to Mountains of southern and central Europe. It grows 10–20 cm (4–8 in) tall and 40–80 cm (16–31 in) wide, wants full sun and low water, and is hardy to about -30 °C (-22 °F). Space plants about 40 cm (16 in) apart.
Plan Rock soapwort in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Rock soapwort at a glance
| Type | Perennial flowering plant, evergreen |
|---|---|
| Family | Caryophyllaceae |
| Mature height | 10–20 cm (4–8 in) |
| Mature spread | 40–80 cm (16–31 in) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance high, waterlogging tolerance none |
| Soil pH | 6–8.5 |
| Cold hardiness | About -30 °C (-22 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 34 °C (93 °F) |
| Flowering | from about May for 4–7 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Moderate |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | Mountains of southern and central Europe |
| Common in gardens of | 🇬🇧 United Kingdom, 🇩🇪 Germany, 🇫🇷 France, 🇮🇹 Italy, 🇺🇸 United States, 🇨🇦 Canada |
Is Rock soapwort toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: all parts
Contains saponins (soap-like compounds) that upset the stomach if eaten.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Rock soapwort
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Questions about Rock soapwort
- How far apart should I plant Rock soapwort?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 40–80 cm (16–31 in).
- Does Rock soapwort need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Rock soapwort need?
- Low water. Drought tolerance is high and waterlogging tolerance none.
- How cold-hardy is Rock soapwort?
- It tolerates about -30 °C (-22 °F) once established, roughly USDA zone 4.
- When does Rock soapwort flower?
- From about May for 4–7 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Rock soapwort poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Contains saponins (soap-like compounds) that upset the stomach if eaten.
- What grows well with Rock soapwort?
- There is no well-documented companion pairing for Rock soapwort. Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- RHS Find a Plant (plant profiles and growing guides), Royal Horticultural Society
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
Notes and assumptions
- A rock-garden plant: give it gritty, very free-draining soil, full light and a collar of gravel around the neck; winter wet kills it far more often than cold.
- Trailing stems that spread into a sheet of small, bright pink flowers in early summer, superb tumbling over a wall. Cut back hard after flowering.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Sweet William Dianthus barbatus
- Carnation Dianthus caryophyllus
- China pink Dianthus chinensis
- Snow-in-summer Cerastium tomentosum
- Moss campion Silene acaulis
- Soapwort (bouncing bet) Saponaria officinalis
- Creeping baby’s breath Gypsophila repens
- Maiden pink Dianthus deltoides