Penstemon Growing Guide

Penstemon barbatus, Penstemon digitalis, other Penstemon species and hybrids

Crop Rotation Group

Miscellaneous ●

Soil

Fertile soil with excellent drainage, with a neutral to slightly alkaline pH.

Position

Full sun to partial shade.

Frost tolerant

Yes, penstemons are hardy perennials, but hardiness varies with cultivar, so check plant tags. Well-rooted plants of the hardiest types can tolerate winter cold to -34°C (-30°F).

Feeding

In spring, topdress the area around penstemons with rich compost or a balanced organic fertiliser.

Spacing

Single Plants: 30cm (11") each way (minimum)
Rows: 30cm (11") with 30cm (11") row gap (minimum)

Sow and Plant

Many penstemons can be grown from seed started in late winter indoors, which is the best way to start numerous plants. Set seedlings out in spring, after freezing weather has passed. In more managed garden situations, consider buying named cultivars as starter plants, because the best characteristics of better perennial penstemons is preserved through vegetative propagation. Start with a purchased plant in spring. Penstemons more than three years old grow into clumps with young plants growing along the outer edges. These can be dug away and replanted to a new spot in early spring. Most penstemons also can be propagated by rooting non-blooming stem cuttings taken in summer.
Our Garden Planner can produce a personalised calendar of when to sow, plant and harvest for your area.

Notes

Native to the American Southwest and Mexico, penstemons are distantly related to foxgloves and snapdragons, producing similar tubular blooms on upright spikes. The flowers attract butterflies. Many cultivars derived from P. digitalis have red stems and foliage, adding to their visual impact in the garden. Size varies with species and variety, with mature height ranging from 30cm (12 inches) to 1.5m (5 feet).

Harvesting

Gather stems for use in cut arrangements when half of the flowers on a stem have opened. Removing old flowers can improve reblooming in many cultivars.

Planting and Harvesting Calendar

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Pests which Affect Penstemon

Aphids (General)

Slug

Snail