Penstemon plants are natives of Northern America and reach from 30 to 90 cm in height.
They can be grown in the garden as hardy perennials or half hardy annuals and perennials.
Penstemon bloom in the summer with tubular lipped flowers; these may be blue, pink, purple, white or yellow. A common name for Penstemon is Beard Tongue.
Penstemon albidus by Matt Lavin.
Common Names: Beard Tongue, Balloon Flower, Cows Tobacco. Penstemon: Garden; Phlox; Heller's; Firecracker; Border; Sand; Box; Parachute; White-margined; Bush; Foothill.
Life Cycle: Hardy annual. Half hardy perennial, hardy perennial.
Height: 4 to 120 inches (10 to 300 cm).
Native: North America. East Asia.
Growing Region: Annual: zones 1 to 10. Perennial: zones 3 to 10.
Flower Details: Red, white, purple, lilac, yellow, blue, pink. Tubular. Two lips. Distinctive staminode.
Foliage: Herbaceous or shrub. Erect. Lanceolate to oblong.
Sow Outside: Surface. Spring and/or autumn. Spacing 12 to 48 inches (30 to 120 cm).
Sow Inside: Germination time: two to five weeks in the light. Temperature 60°F (16°C). Two months before expected last frost. Transplant outdoors following the last.
Requirements: Full sunlight or light shade. Good drainage. Soil pH 5.5 to 7. Rich soil. Regular watering during prolonged dry periods. Deadhead. Perennials should be cut back to the ground in autumn. Autumn mulch for perennials once cut back. Winter mulch. Propagate: cuttings can be took from stems in either autumn or in the spring.
The seeds of Beard Tongue/Penstemon can be sown outdoors in either spring or autumn; the Penstemon plant seeds should be sown on the soil surface. They like to grow in sunny areas (though requires partially shade in hot areas); ideally the soil should be fertile and slightly acidic to neutral (pH 5.5 to 7), the ground that the plant grows in should also have good drainage.
If starting off indoors ten do so about 9 or 10 weeks before the last frost of spring is expected. The seeds should be germinated in the light at 12 to 18 degrees centigrade; it should take about 3 to 6 weeks. Once ready transfer the young Penstemon plants outside at about 30 cm (small species) to 75 cm (larger varieties) apart.
To look after Beard tongue and other Penstemon plants it is best to water regularly and dead head the flowers once they have finished blooming. Once the season has finished in the autumn cut the plants down to the ground; it is a good idea to mulch the ground that Penstemon grow in at the same time. If you require more plants for your garden they can be propagated by taking stem cuttings; this can be done in either spring or autumn.