Dictionary of Flowers: Penstemon (Beard Tongue)

Penstemon (or the weird aka of Beard Tongue) has beautiful bi-color trumpet-shaped flowers. Image used under a Creative Commons licence with the kind permission of Manuel and Flickr

Penstemon (or the weird aka of Beard Tongue) has beautiful bi-color trumpet-shaped flowers. Image used under a Creative Commons licence with the kind permission of Manuel and Flickr

  • Penstemon
  • Common name: penstemon, beard tongue
  • Family:  Plantaginaceae
  • Category: Perennial in USDA zones 3-9, depending on varieties
  • Height: 8” to 24” 
  • Width: 8” to 20”
  • Sun/part shade
  • Blooms: late spring to late summer
  • Attracts: hummingbirds, butterflies
  • Growth habit: upright, bushy, mat forming. Used as a filler or thriller in container combinations
  • Maintenance: easy
  • Soil: poor to average, well drained. Water regularly if grown in containers. Drought tolerant
  • Garden uses: containers, mixed border, rockery, cutting garden, wildflower garden
  • Diseases: powdery mildew, leaf spot, rust. Rot if grown in wet conditions
  • Pests: slugs and snails, nematodes

Short lived perennial, native to the entire United States, Canada, Mexico and Central America where it can be found in the wild in all kinds of natural habitats.

Penstemon is a large genus of mostly herbaceous perennials. Most penstemons have small lance shaped leaves. Flowers are very similar to open snapdragons, though smaller.

They grow on spikes. Their color range is wide, from white to purple, pinks, yellows, red, or violet.

They are suited to xeriscaping, as most are drought tolerant once established. 

They attract hummingbirds, providing a source of nectar for bees and butterflies as well.

Different species have different cultivation requirements. Most of them prefer to grow in full sun to part shade in average soils. Avoid rich soils.

They don't require much water when grown on the ground, most just need watering every other week during dry summer weather. Avoid mulches, they can cause rot in wet weather.

Penstemons don't require much fertilizer. Once a year, feed an organic fertilizer, either in spring or fall. Remove spent flower stalks to promote more blooms. 

Don't trim penstemon in fall or winter, wait till spring to remove dead stems.

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Species penstemons can be difficult to find in nurseries. It is easier to find hybrid cultivars well suited for the specific area they are purchased at.

Beard tongue can be propagated by softwood cuttings and seed. Cut non-flowering stems about four inches long, remove the bottom leaves. Dip the cut end in rooting hormone and insert in a mixture of moist potting soil and perlite or sand.

Once they root, they need to be planted in larger containers or the ground to survive winter in colder zones. 




Established plants can also be divided either in early spring or late summer. 

They can also be grown from seed, though seed from hybrid varieties won't look like the parent plant. Penstemon seed can be wintersown, as it needs a cold and moist stratification period.

If sowing indoors, sow seed in moist starting mix and do not cover. When kept at about 60F, it will take two weeks to a month to germinate. If germination doesn't happen, move flats to the refrigerator, keep there a couple weeks and bring them out to room temperature again.

Penstemon seed can also be sown in the late fall or early winter in the spot they are to be grown in the garden. Scatter seed and cover with a thin layer of coarse sand.

They will sprout during spring.

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Mildew or leaf spot and rust can happen if grown on wet and humid conditions. Improve conditions and treat with a fungicide.

When nematodes are a problem, apply an insecticidal soap or plant marigolds nearby to deter this parasite. Remove all affected parts and discard.  Slugs and snails can bother penstemon during wet weather. Bait as needed. Penstemon is deer resistant.

Popular varieties:

  • Penstemon barbatus 'Pina Colada' - blooms the first year when started from seed early. Twelve inches high
  • Penstemon barbatus 'Navigator Mix' - Twelve inch tall plants. Flowers can be pink, white, purple and rose. Heat and humidity tolerant
  • Penstemon digitalis 'Husker's Red' - Burgundy colored foliage. White blooms on two to three foot plants
  • Penstemon hartwegii 'Tubular Bells' series - large blooms, heat tolerant. Can bloom the first year when planted early. Up to one and a half feet tall
  • Penstemon tenuis - good for warmer zones with high humidity. Lavender blooms
  • Penstemon eriantherus - this species works well in cooler zones with lots of rain. Lavender flowers
  • Penstemon barbatus 'Cambridge Mix' - about a foot tall plants good for northern gardens. Compact shape. Colors range from pink to purple and rosy reds

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Click to see Ophiopogon Planiscapus (Mondo grass)
Click to see Platycodon Grandiflorus (Balloon Flower)

Full List of Dictionary of Flowers Entries

Annuals For Containers

Perennials For Containers

Go from Penstemon (Beard Tongue) to the Dictionary of Flowers

More great ideas for Container Gardening!

Leave Comments

Have your say about what you just read! Leave me a comment in the box below.