Penstemon plants are natives of Northern America. They can reach from 30 to 90 cm (1 to 3 feet) in height.
They can be grown in the garden as hardy perennials, half hardy annuals, or 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.
Penstemon eatonii (Eaton's Penstemon / firecracker Penstemon), photograph by Andrey Zharkikh; CC.
Penstemon strictus (Rocky Mountain Penstemon), photograph by Andrey Zharkikh; CC.
Penstemon hirsutus (Hairy Beard-tongue / Northeastern Beardtongue), photograph by Doug McGrady; CC.
Penstemon heterophyllus (Bunchleaf Penstemon / Foothill Beardtongue), photograph by Tom Hilton; CC.
Penstemon spectabilis (Showy Penstemon / Showy Beardtongue), picture by peganum; CC.
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.
The seeds of Beard Tongue/Penstemon can be sown outdoors in either spring or autumn.
Penstemon plant seeds should be sown on the soil surface.
They like to grow in sunny areas (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, then do so about 9 or 10 weeks before the last expected frost of spring.
The seeds should be germinated in the light, at 12 to 18 degrees centigrade (54 to 64°F). Germination should take about 3 to 6 weeks.
Once ready, transfer the young Penstemon plants outside at a spacing of about 30 cm (12 inches; small species) to 75 cm (30 inches; larger varieties).
To look after Beard tongue and other Penstemon plants, it is best to water regularly and to deadhead 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.
I hope that you enjoyed this guide on how to grow Penstemon plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Purple Bell Vine, Iris plant, Boussingaultia plant, and Collinsia plants.