Soapwort
Check which kind you have before planting: the mat-forming rockery species stays where it is put, while the tall soapwort will travel through a border given the chance.
Care
Full sun — needed for dense growth and a good flush of flower.
Low — drought-tolerant once established and happiest on dry banks and walls.
Poor, free-draining, preferably alkaline soil. It grows on gravel, walls and stony banks and asks for nothing better.
Shear the trailing kinds back hard immediately after flowering — this keeps the mat dense and prevents the bare, woody centre they otherwise develop. Cut the tall running species to the ground in autumn.
No feeding. On good soil it grows lax and flowers less, and the tall species becomes seriously invasive when well fed.
Divide in spring, or take softwood cuttings in early summer from the non-flowering shoots. The running species spreads by underground stems, so a rooted piece lifted with a trowel is an instant new plant — and thinning it is usually the more pressing job.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilLift and reduce the running species before it colonises its neighbours.
- JulyShear the trailing kinds back hard straight after flowering. how ›
- OctoberCut the tall species to the ground once it has died down. how ›
Months based on climate: UK. Your choice stays on this device.
- AprilLift and reduce the running species before it colonises its neighbours.
- JulyShear the trailing kinds back hard straight after flowering. how ›
- OctoberCut the tall species to the ground once it has died down. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
- MarchLift and reduce the running species before it colonises its neighbours.
- JulyShear the trailing kinds back hard straight after flowering. how ›
- OctoberCut the tall species to the ground once it has died down. how ›
Months based on climate: Central Italy. Your choice stays on this device.
- MarchLift and reduce the running species before it colonises its neighbours.
- JulyShear the trailing kinds back hard straight after flowering. how ›
- NovemberCut the tall species to the ground once it has died down. how ›
Months based on climate: Southern Italy and islands. Your choice stays on this device.
Common problems
How to spot it. The tall species running through a border by underground stems.
What to do. Grow it in rough ground or a contained bed; lift and reduce it every spring.
How to spot it. A rockery mat that has died out in the middle.
What to do. Shear hard after flowering each year; replace or divide an old plant.
How to spot it. Blackened patches in the mat on heavy soil.
What to do. Plant on a slope, wall or gravel rather than in a flat border.
Questions
Soapwort: is it hardy?
H5: Hardy in most of the UK, but can struggle in the coldest inland or upland spots. It survives down to −15 °C.
Can it grow in a pot?
Yes for the trailing rockery kinds, which suit a trough or the edge of a raised bed; the tall running species is not a container plant.
Soapwort: when do you prune it?
Shear the trailing kinds back hard immediately after flowering — this keeps the mat dense and prevents the bare, woody centre they otherwise develop. In the calendar for UK, pruning falls in July, October.
Soapwort: when does it flower?
In the climate of UK it flowers in May–July.
When do you feed it?
No feeding. On good soil it grows lax and flowers less, and the tall species becomes seriously invasive when well fed.