Davidson's Penstemon

Penstemon davidsonii is an exceptional, low-growing, evergreen sub-shrub that is perfectly suited for the UK rock garden. It forms a dense, prostrate mat of small, leathery, oval green leaves that often take on bronze tints in cold weather. In early summer, it produces remarkably large, tubular, lavender-blue to purple flowers that are held horizontally just above the foliage. On a healthy specimen, the flowers can be so numerous that they completely hide the plant. Native to alpine regions of North America, it is very hardy (H4) and thrives in a position of full sun with excellent drainage. It is particularly effective when planted in a rock crevice or allowed to sprawl over a large stone, where its woody stems can trail and root. To keep the plant vigorous and compact, it is advisable to lightly prune the flowering stems back after the blooms have faded. It is a reliable and showy alpine that provides excellent ground cover.

Sun: Full sun.

Soil: Sharply drained, poor to moderately fertile soil.

Hardiness: H4 — down to −10°C.

Flowering: May, Jun.