About
Penstemon strictus, the Rocky Mountain penstemon, is an evergreen perennial to 75 cm forming large clumps of rich-green, lance-shaped, slender leaves and producing upright spikes of royal-blue to purple, tubular flowers over a long period from early summer. One of the most reliable and striking of all hardy penstemons for a sunny, well-drained border.
About the genus
Penstemon are deciduous or evergreen perennials or subshrubs with simple, narrow leaves and racemes or panicles of tubular, bell-shaped or funnel-shaped flowers in summer and early autumn, in shades of red, pink, purple, white and bicolours. Excellent plants for sunny, well-drained borders.
Growing conditions
SunlightFull sun
Soil typeChalk, Loam, Sand
Soil pHAcid, Alkaline, Neutral
Soil moistureWell-drained
AspectSouth-facing, West-facing
ExposureSheltered
UK hardinessH5
Plant details
Plant typeHerbaceous Perennial
HabitClump forming
FoliageSemi evergreen
Height0.5-1 metres
Spread0.5-1 metres
Time to full height2-5 years
Suggested usesCity and courtyard gardens, Coastal, Cottage and informal garden, Gravel garden, Patio and container plants, Prairie planting, Wildlife gardens
Native toUnited States
Care notes
CultivationGrow in fertile, well-drained soil in full sun or partial shade. In cold areas, protect plant overwinter with dry winter mulch. See penstemon cultivation
PruningDeadhead after flowering to maintain vigour and prolong flowering, then cut back to 15cm in late winter or early spring
PropagationPropagate by seed in late winter or spring, softwood cuttings in early summer or semi-ripe cuttings in midsummer
Pest resistanceMay be susceptible to slugs, snails, aphids and leaf and bud eelworms
Disease resistanceMay be susceptible to downy mildews, grey moulds, powdery mildews and a fungal leaf spot