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Herbaceous Perennial

Penstemon strictus

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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Ultimate height

0.5–1 metres

Time to ultimate height

2–5 years

Ultimate spread

0.5–1 metres

Chalk

Loam

Sand

Moisture

Well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

South–facing or West–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Plantaginaceae
Native to GB / Ireland: 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

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