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Reliable and colourful Penstemons

Penstemon is growing in popularity and is used in gardens worldwide.

Penstemon is growing in popularity and is used in gardens worldwide.


Growing penstemons (also known as Beard Tongue)  is incredibly easy, with very little care and attention required. Purchase plants in summer while in bloom to ensure you get the colour you want. Water regularly during the first season. Once the plants are established they will be fairly drought tolerant.

Penstemons are easily grown from seed, which may be sown in the open in late autumn, or at any time during the winter. Seed beds should be very firm, almost hard; seed of the large seeded kinds should be planted about 6mm deep. Those of the tiny seeded species should not be covered over 1mm, or they may even be sown on the surface and pressed into the soil.

Plants from the nursery, or from your seed bed can be transplanted with minimum care. The root system is much like that of a strawberry, and transplanting is done in the same manner. It is helpful to build a little cone of soil in the bottom of the planting hole, and to spread the fibrous roots over that. The crown of the plant should be at soil level with the roots well spread. The soil should be well packed over the roots and watered. The crown must not be covered with soil. Soil should be kept moist during establishment, but should not be kept muddy.

Penstemons are one of the most useful and long-flowering of our garden plants: they hold no fascination for slugs, they shrug off the depredations of both drought and rain, and they are pretty happy in both sun and a bit of shade. Even if you’re so unfortunate as to lose a plant, the good news is that penstemons are easy to propagate from cuttings. If pushed into some good compost, a 10cm piece of non-flowering shoot, cut to just below a leaf node, will soon send out roots and be up and flowering by the following season.

Breeders have been happily hybridising these flowers for more than 100 years – there area a lot of cultivars available in many colours, from pure white through to candy pink and all stops in between. There are plants that reach only 15cm, others that are a robust 90cm. The flowers are pollinated by bees, wasps, moths, butterflies, flies, and hummingbirds.


The American Penstemon Society Manual for Beginners advises that to get the most satisfaction out of penstemons, they should be used in the garden with consideration for their special characteristics. Kinds suited only to a rock garden should not be put in a perennial border with tall-growing plants that will crowd them out or cover them up. Kinds suited for the border are seldom appropriate in a rock garden.

If tall penstemons are to be used in a border, it is wise to avoid the kinds that tend to be short-lived. They are apt to die after blooming and leave holes in the border. Or, if short-lived ones are used, they should be kinds that make seedlings for the next year from their own dropped seeds. Kinds that do not do that will have to be raised in a seed bed and set out each year as with bedding plants. If the border is kept mulched, the dropped seed may not germinate so only long-lived kinds should be used. If the plants are grown in a special bed of their own, the seed can be scattered or allowed to drop between the plants, the soil being left bare; and there would be seedlings to take the place of the ones that die. If you do not mind raising seedlings each year for replacement, you may disregard what we have just said about using short-lived kinds in a border.

In general, penstemons of the border type are more satisfactory when grown in masses rather than individually. One individual plant relied on for a good display may turn out to be disappointing through failure to bloom well, but in a group of a dozen or fifty, the mass effect will be pleasing even if one or two individuals should fail to live up to expectations.

Penstemon is native to North America. Native Americans used penstemons medicinally to relieve pain, treat snake bites and other health problems.

Pruning tips

Do not cut back the flowering stems in the autumn as they help to protect the crown of the plant and its new shoots from the frost. When new shoots appear at the base, and all 
danger of heavy frost is passed, then you can cut most Penstemons well back, being careful not to damage the new shoots.

Technical Data

Penstemon (tribe Cheloneae: Scrophulariaceae) is a large genus (about 275 species) of perennial plants endemic to North America, ranging from Alaska to Guatemala and from coast-to-coast, exclusive of the Canadian shield. It has been divided into six subgenera.  Floral colors include white, yellow (rare), blue, violet, purple, pink, magenta, and red. Corollas can be tubular or funnel shaped.