Penstemon barbatus

RHS Plant Profile

bearded penstemon

RHS

Other common names

bitterherb, bitterweed, broom-shell flower, cod head, firecracker plant, fish mouth

Synonyms

Chelone barbata

Herbaceous Perennial

A tall, upright perennial to 1.8m with semi-evergreen basal rosettesand deciduous stems with leaves up to 20cm long. From early summer to early autumn bears loose spires of hanging, tubular red flowers 4cm long tinged pink to carmine.

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.1-0.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Chalk Loam Sand

Moisture: Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: South–facing or East–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): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

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: Mexico & S USA

How to Grow

Cultivation

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

Propagation

Propagate by softwood cuttings in early summer, semi-hardwood cuttings in midsummer, or division in spring

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Gravel garden
Patio and container plants
Coastal
Wildlife gardens
Flower borders and beds
Cut flowers

Pruning

Deadhead after flowering to maintain vigour, then cut back to base in winter

Pests

May be susceptible to slugs, snails and chrysanthemum eelworms

Diseases

May be susceptible to downy mildews