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Herbaceous Perennial

Penstemon strictus
  • RHS Plants for pollinators

Rocky Mountain penstemon

Evergreen perennial to 75cm tall, 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

Other common names
stiff beard-tongue
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Size
Ultimate height
0.5–1 metres
Time to ultimate height
2–5 years
Ultimate spread
0.5–1 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Blue Purple Green
Autumn Green
Winter Green
Position
  • Full sun
Aspect

South–facing or West–facing

Exposure
Sheltered
Hardiness
H5
Botanical details
Family
Plantaginaceae
Native to the UK
No
Foliage
Semi evergreen
Habit
Clump forming
Genus

Penstemon may be deciduous or evergreen perennials or subshrubs, with simple, narrow leaves and racemes or panicles of bell-shaped or funnel-shaped flowers in summer and early autumn

Name status

Correct

Plant range
United States

How to grow

Cultivation

Grow in fertile, well-drained soil in full sun or partial shade. In cold areas, protect plant overwinter with dry winter mulch. See penstemon cultivation

Propagation

Propagate by seed in late winter or spring, softwood cuttings in early summer or semi-ripe cuttings in midsummer

Suggested planting locations and garden types
  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Gravel garden
  • Patio and container plants
  • Prairie planting
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds
Pruning

Deadhead after flowering to maintain vigour and prolong flowering, then cut back to 15cm in late winter or early spring

Pests

May be susceptible to slugs, snails, aphids and leaf and bud eelworms

Diseases

May be susceptible to a downy mildew, grey moulds, Powdery mildews and a fungal leaf spot

Get involved

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