Perennial
Penstemon
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Flowers | Flowers in June | Flowers in July | Flowers in August | Flowers in September | Flowers in October | |||||||
| Plant | Plant in April | Plant in May | Plant in June | |||||||||
| Prune | Prune in April | |||||||||||
| Looks good | Looks good in June | Looks good in July | Looks good in August | Looks good in September | Looks good in October |
Overview
Upright stems carry foxglove-like tubular flowers in red, pink, purple, blue and white over a very long season. Bumblebees climb right inside them. The hardiest are the narrow-leaved varieties: 'Garnet' (also sold as 'Andenken an Friedrich Hahn') is wine red and reliably tough, 'Sour Grapes' is a smoky violet, and 'Raven' is deep purple with a pale throat. Broad-leaved, large-flowered types are showier but less hardy.
Where to grow penstemon
Choose a sunny or lightly shaded spot sheltered from cold winds, in soil that drains freely in winter. They are happy on chalk and in coastal gardens. In cold, wet inland areas they are worth placing near a warm wall.
Planting
Plant in late spring so roots establish before winter, 45 cm apart. Avoid autumn planting, which often leads to losses.
Care through the year
Spring
Once new shoots appear at the base, cut old stems back to just above them.
Summer
Deadhead regularly and water in long dry spells.
Autumn
Take cuttings now as insurance against a hard winter.
Winter
Leave the old top growth on; it shields the crown from frost.
Pruning
Wait until mid-spring, when frosts are easing and fresh growth is visible, then cut stems back to just above the new shoots. Cutting earlier exposes the plant to cold damage.
Propagation
Take non-flowering shoot tips about 8 cm long in late summer, root them in gritty compost and overwinter the young plants in a cold frame or porch.
Common problems
Winter wet kills more penstemons than cold; improve drainage with grit. Powdery mildew can appear late in the season, and slugs eat new shoots. Plants that grow woody and sparse after a few years are best replaced by young cuttings.
Something else wrong? Diagnose it by symptom.
Month-by-month reminders
Jobs for this plant come round in April, May and June. Each month page lists everything else worth doing in the garden at the same time.
Related plants
Sources
Botanical names follow Kew's Plants of the World Online; growing attributes were checked against the references below. Text is our own. See our editorial policy.