The catalogue may sing the praises of this perennial – glossy, attractive tubular clustered on erect spikes all summer long, etc, but it is only reliable in sheltered areas with a better than average climate. It is killed by severe winter frosts, especially if the ground is not free-draining, and even in mild regions its life span is usually less than five years. Of course, this challenge may encourage you to grow it – then water copiously in dry weather, dead-head faded blooms, cut down the in autumn and cover the crowns with peat in winter. If you don’t like to gamble then grow Penstemon from as a summer-flowering bedding plant.
VARIETIES: The popular hybrids are grouped under P. gloxinioides (P. hartwegii) and red is the favourite colour. Basic details are height 1.5-2 ft. Spacing 1 ft.
Flowering period: June-September. ‘Firebird’ is the red variety which is usually offered, but ‘Garnet’ is hardier. ‘Sour Grapes’ bears slate-blue flowers. Many garden centres offer P. barbatus which flowers at the same time as the hybrids but is taller – height 3 ft. Spacing 1Vfc ft. flower colours white, pink and red.
SITE AND SOIL: A well-drained soil is essential – thrives best in full sun.
PROPAGATION: Plant cuttings in a cold frame in late summer.