Penstemon glaber 'Roundway Snowflake'

RHS Plant Profile

penstemon 'Roundway Snowflake'

Herbaceous Perennial

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glaber 'Roundway Snowflake' is a semi-evergreen perennial to 60cm high carrying several stems of narrow glossy, dark green leaves and from early and midsummer short spikes of tubular white flowers

Position

Full sun, Partial shade

Soil Types

Chalk, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.1-0.5 metres
Max Height: 0.5-1 metres

Growing Conditions

Chalk Loam Sand

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

Position

Full sun Partial shade

Aspect: South–facing or East–facing or West–facing
Exposure: Exposed or 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): H4

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: Accepted

How to Grow

Cultivation

Grow in fertile, 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

Propagation

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

Suggested planting locations and garden types

Gravel garden
City and courtyard gardens
Coastal
Cottage and informal garden
Patio and container plants
Prairie planting
Wildlife gardens
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 downy mildews, grey moulds, powdery mildews or a fungal leaf spot