Penstemon 'Sour Grapes' — Clump forming

Overview

Penstemon 'Sour Grapes' is a clump forming perennial in the genus Penstemon, part of the Plantaginaceae family, with semi evergreen foliage. Penstemon 'Sour Grapes' grows best in full sun, and tolerates most soils and any pH. Its UK hardiness is rated H4. Suggested uses include city and courtyard gardens, coastal, cottage and informal garden, wildlife gardens, flower borders and beds and wall side borders.

About

Penstemon 'Sour Grapes' is a cultivar of Penstemon (family Plantaginaceae) distinguished by the genus's two-lipped, tubular flowers and the prominent sterile stamen or staminode. Each bloom shows the characteristic bearded palate that gives beardtongues their common name. Flowering in the UK runs from June to September. The flowering stems carry multiple blooms, making the staminode readily visible on each flower.

About the genus

Penstemon, the beardtongues, is a large genus of roughly 280 species of flowering plants native to North America from northern Canada to Central America. It is the largest genus of flowering plants endemic to North America. As well as being the scientific name, penstemon is also widely used as a common name for all Penstemon species alongside beardtongues.

Wikipedia contributors, "Penstemon", CC BY-SA 4.0 — Penstemon

In the garden

Penstemon 'Sour Grapes' sits within the genus Penstemon and the family Plantaginaceae; its flowers display the typical tubular, two-lipped corolla and the conspicuous staminode that helps identify beardtongues. In the UK it flowers from June to September, producing repeated displays of these diagnostic blooms over the summer months. Growers treat Penstemon cultivars to promote clean-looking plants and prolonged bloom. Provide a position where water does not sit around the roots, and remove spent flower spikes to keep the plant tidy and to encourage further flowering. A short prune of the flowering stems after the main season will refresh growth and prepare the plant for the following year. Use individual plants where their upright flowering stems can be appreciated — the floral structure is easiest to inspect close to head height. The visible staminode on each corolla makes Penstemon 'Sour Grapes' useful for teaching or demonstrating the distinctive morphology of beardtongues to visitors or students interested in flower form. Flowering runs June to September, during which the staminode and the two-lipped flowers are most apparent.

Growing conditions

Best soil and position for Penstemon

Sunlight: Full sun
Soil type: Chalk, Loam, Sand
Soil pH: Acid, Alkaline, Neutral
Soil moisture: Well-drained
Aspect: South-facing, West-facing, East-facing
Exposure: Exposed, Sheltered
UK hardiness: H4

Plant details

Penstemon 'Sour Grapes' size, habit and characteristics

Plant type: Perennial
Habit: Clump forming
Foliage: Semi evergreen
Suggested uses: City and courtyard gardens, Coastal, Cottage and informal garden, Wildlife gardens, Flower borders and beds, Wall side borders

Care notes

Pruning and caring for Penstemon 'Sour Grapes'

Propagation: Softwood cuttings in early summer, Semi-ripe cuttings in midsummer, Division in spring
Pest resistance: Slugs, Snails, Aphids, Leaf and bud eelworms
Disease resistance: Downy mildews, Grey moulds, Powdery mildews, Fungal leaf spot

Frequently asked questions

Where is the best place to plant Penstemon 'Sour Grapes'?

Penstemon 'Sour Grapes' prefers full sun. It suits exposed and sheltered positions.

What soil does Penstemon 'Sour Grapes' need?

Penstemon 'Sour Grapes' is adaptable and grows happily in most soil types, including chalk, loam and sand. It is happy in soil of any pH. Aim for soil that stays well-drained.

Is Penstemon 'Sour Grapes' hardy in the UK?

Penstemon 'Sour Grapes' has an RHS hardiness rating of H4, meaning it is hardy through an average UK winter, tolerating -10 to -5°C.

How do I propagate Penstemon 'Sour Grapes'?

Softwood cuttings in early summer, Semi-ripe cuttings in midsummer, Division in spring.

More in the Penstemon genus

Browse all Penstemon →