About
Penstemon 'Castle Forbes' is a compact, bushy, semi-evergreen, drought-tolerant perennial with dark-green, strap-shaped foliage. Upright spikes of long-lasting, tubular, rose-red flowers with white throats are produced from June to October. A rewarding and reliable border penstemon for a sunny, well-drained position.
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, Partial shade
Soil typeChalk, Loam, Sand
Soil pHAcid, Alkaline, Neutral
Soil moistureWell-drained
AspectEast-facing, South-facing, West-facing
ExposureExposed, Sheltered
UK hardinessH4
Plant details
Plant typeHerbaceous Perennial
HabitBushy
FoliageSemi evergreen
Height0.5-1 metres
Spread0.5-1 metres
Time to full height2-5 years
Suggested usesCity and courtyard gardens, Cottage and informal garden, Wildlife gardens
Care notes
CultivationGrow in fertile, moist but well-drained soil in full sun or partial shade. In cold areas, protect plant overwinter with a dry winter mulch. See penstemon cultivation for further advice
PruningDeadhead after flowering to maintain vigour and prolong flowering, then cut back to 15cm in late winter or early spring
PropagationPropagate by softwood cuttings in early summer or semi-hardwood cuttings in midsummer. Propagate by division in spring
Pest resistanceMay be susceptible to slugs, snails, aphids and leaf and bud eelworms
Disease resistanceGenerally disease-free but may be susceptible to powdery mildews and grey moulds