Foxglove Beardtongue 101 – Guide to Penstemon Digitalis


Foxglove Beardtongue is one of the showier native wildflowers in North America. Frequently seen in clearings, ditches, and prairies, the white flowers are excellent for attracting pollinators and looking nice all year. I’ve germinated and grown these flowers for my gardens for several years, and love the white flowers they produce and wildlife they attract.

Now I will share what I’ve learned over the years with you. This will be a complete profile on this lovely native flower.

In this article:

What is Foxglove Beardtongue

Foxglove Beardtongue is a perennial flower native to Eastern North America. Scientifically known as Penstemon digitalis, it grows up to 3′ tall in full sun and moist to medium-moist soil that drains well. Blooming showy white flowers for about one month in late Spring, it attracts numerous species of long-tongued bees and hummingbirds.

The fact that Foxglove Beardtongue makes a beautiful display in the garden and doesn’t spread aggressively make it one of the best native plants for residential landscaping.

==>Read why Native Plants are so critical to our environment here

It’s common name, Foxglove Beardtongue pays homage to it’s resemblance to European Foxglove, Digitalis purpurea. It is a member of the Plantain family (Plantaginaceae). In the past it was a member of the Figwort family, but was reclassified several years ago.

Foxglove Beardtongue looks stunning in mass plantings

Native Range of Foxglove Beardtongue

The native range of Foxglove Beardtongue generally follows the river valleys of the American Midwest, out East to Pennsylvania, Virginia, with isolated pockets scattered throughout the South and Eastern United States.

Source [3]. Click on image to see full size.

Foxglove Beardtongue Reference Table

Scientific NamePenstemon digitalis
Common Name(s)Foxglove Beardtongue, Foxglove Penstemon, Smooth White Beardtongue, White Penstemon
Native Range, USDA ZoneAmerican Midwest, Midatlantic, Southern USA. Hardiness Zone 3-8
Bloom TimeLate Spring to early Summer
Bloom Duration, ColorFlowering period lasts approximately 4 weeks, white colored blooms
Height2-3′ (60-90 cm)
Spacing / Spread18″-24″ (45-60 cm)
Light RequirementsFull sun to partial shade
Soil TypesSandy, Sandy-loam, loam, clay loam – must be well draining soil!
MoistureMoist to medium moist
Fauna Associations / Larval HostsLong tongued bees, moths, butterflies, hummingbirds
Sources [1], [2], [3]

What are the Benefits of Foxglove Beardtongue

Beauty

Foxglove Beardtongue makes a striking display when planted in groups of three or more. The showy white flowers hanging down in clustered panicles are striking whether in a field or a formal flower bed. Plus, the basal foliage is semi-evergreen, which keeps the plant interesting year round.

Long bloom time

With a bloom time of approximately one month, Foxglove Beardtongue keeps gardens in bloom for a long time. Furthermore it covers a ‘blooming’ gap between Spring ephemeral flowers / bulbs and the start of Summer flowers.

Versatile

Although it typically prefers moist or medium-moist soils, Foxglove Beardtongue has shown itself to be adaptable to a wide range of conditions. It can be grown on all but really dry sites.

Pollinator favorite

This is one of the first plants to start drawing in bees after the flowers of the trees have bloomed. Numerous species of bee frequent the plant, and even hummingbirds too. (Although I’ve not seen mine visited).

Bumblebee on Foxglove Beardtongue, Penstemon digitalis

Identification and Characteristics of Foxglove Beardtongue

Stalk

The stalk approximately 3′ tall, green to purple in color and hairless. It is generally erect but can flop over or break off after flowering.

Related => If you love the look of Foxglove Beardtongue, but think it might be a bit too tall, then you should look at it’s shorter cousin, Hairy Beardtongue.

Leaves

Foxglove Beardtongue has two types of leaves for identification. There is a cluster of basal leaves on the ground, and then leaves along the stalk.

Basal leaves

The basal leaves of Foxglove Beardtongue may be a single or multiple rosettes clustered together. During the growing season they are green and can turn purple in colder weather. The shape can vary between ovate to lanceolate with smooth edges/margins. The size varies from 2-6″ long by 1-2.5″ wide.

Basal rosette leaves of two Foxglove Beardtongue plants.

Stalk leaves

The leaves on the flowering stalks of Foxgolve Beardtongue are opposite along the stalk, green, and lanceolate in shape with small teeth on the edges. They range from 3″-6″ long by 1″-3″ wide.

Foxglove Beardtongue stalk and leaves

Yellow leaves on Foxglove Beardtongue

During times of drought, the leaves on Foxglove Beardtongue may turn yellow. If this happens, provide some supplemental water.

Flower

The bloom time and duration of Foxglove Beardtongue is about 1 month beginning in late Spring and extending until early Summer. Clusters of white flowers at the top of each flowering stalk in a panicle. Individual blooms are tubular in shape with two upper and three lower lobes. The flowers have no obvious scent.

Fruit

After blooming period has ended, Foxglove Beardtongue will develop small fruits where individual flowers once were. It is an oval shaped seed capsule that will contain many small hard seeds. The entire stalk will turn dormant and can break off / flop over. But the basal leaves at the base of the plant will still remain green.

Fruit of Foxglove Beardtongue, Penstemon digitalis

The seed pods generally stay in-tact on the stalk throughout most of the Winter. You can save the seed in the same manner as other Penstemon flowers. We have written a detailed guide on saving Penstemon seed here.

Root

The root system of Foxglove Beardtongue is short rhizomes that can form clumps of plants.

Lifecycle

I’ve created the info-graphic below to give you an idea as to what Foxglove Beardtongue looks like in all four seasons. I hope you find it helpful. Note that in the ‘Fall’ picture the flowering stalks are still upright. And in Winter they have been removed.

Difference between “Foxglove Beardtongue” and “Foxglove”

It can be confusing when speaking about ‘common’ names of flowers. And this is further compounded when flowers look similar. And it is very important for you to be able to know the difference between Foxglove Beardtongue and Foxglove, as the latter is very toxic to humans. [4]

Foxglove Beardtongue and “Foxglove” are not the same, and are completely different species. While “Foxglove Beardtongue” (Penstemon digitalis) is native to North America, “Foxglove” (Digitalis purpurea) is an import from Europe that has become naturalized in parts of North America.

You can visually tell these species apart by examining the leaves on the flowering stalk as Foxglove Beartongue has paired, or opposite leaves. While ‘Foxglove’ has alternate or staggered leaves up the stalk. Also, while both have basal leaves, leaves of “Foxglove Beardtongue” are hairless while ‘Foxglove’ basal leaves are fuzzy.

Differences between Foxglove Beardtongue and Foxglove

CharacteristicFoxglove BeardtongueFoxglove
Latin / Scientific NamePenstemon digitalisDigitalis purpurea.
Basal LeavesSmoothFuzzy
Leaves on flowering stalkOpposite (paired along stalk)Alternate
(Staggered along stalk)
StalkSmooth, hairlessFuzzy
FlowersTubular with 5 lobesTubular, no lobes
Sources [1], [2], [4]

And here is a nice visual comparison to show the different leaf arrangement and flower differences;

Grow and Care for Foxglove Beardtongue

Natural habitat of Foxglove Beardtongue

Foxglove Beardtongue occurs naturally along roadsides, railroad tracks, open woodland areas, along forest borders, and in prairies. You can also frequently encounter it in abandoned feels, farm pastures, thickets – just about anywhere that has good drainage and plenty of sunlight.

Sunlight Requirements

Foxglove Beardtongue prefers full sun, which is at least six hours of direct sunlight per day. However it will tolerate partial shade, which is 4-6 hours of direct sunlight per day.

Soil Requirements

For soil, Foxglove Beardtongue is adaptable to many soils as long as it drains well. It will grow well in sandy, sandy loam, and clay-loam if it drains well.

If unsure of what type of soil you have, you can read our guides to test the drainage and soil texture.

Moisture Requirements

Foxglove Beardtongue perfers medium moisture to moist soil. It can tolerate drought, but the leaves may yellow.

But take care to make sure it’s location has good drainage. Foxglove Beardtongue can be killed from root rot.

Maintenance

Foxglove Beardtongue does not require manitenance and will look good throughout all four seasons. But, it can self-seed a bit, so if you do not wish this to happen, you should cut off the seed heads before Winter.

Fertilizer Requirements

Like many Native Plants, Foxglove Beardtongue does not require any fertilizer or compost to grow healthy, tall, and showy. You do not need to fertilize Foxglove Beardtongue.

Foxglove Beardtongue Planting Guide

To transplant Foxglove Beardtongue, the most important factor is location. Foxglove Beardtongue will prefer full sun and well drained soil. Be cautious about planting Foxglove Beardtongue in clay soil, as you need to make sure it drains well. If you are unsure as to how well your soil drains, you can learn to test the soil drainage here.

How to Grow Foxglove Beardtongue from Seed

Growing and propagating Foxglove Beardtongue is fairly straight forward. It requires exposure to sunlight to germinate and a cold/moist stratification period of approximately 4 weeks. Not exposing Penstemon seed to a cold/moist period will significantly reduce the germination rate. [5]

Seeds of Foxglove Beardtongue, Penstemon digitalis

The numerous seeds in the capsules are very tiny, perhaps 1mm diameter.

You need to either cold-stratify the seeds in the refrigerator for 30 days, or Winter-sow the seeds in order to break the seeds dormancy. We have guides on both cold stratifying the seed in the refrigerator, and Winter Sowing. I suggest you read each to determine what method you would prefer.

Process to germinate Foxglove Beardtongue Seeds in containers

The following steps assume you are either Winter Sowing or have already cold-stratified your seeds in the fridge.

  1. Prepare a container with moist potting soil. Make sure the soil is moist, not wet. If you squeeze a handful, only a few drops of water should fall out. Pack the soil firm in the container, leaving about 1/2″ (12 mm) gap from the top.
  2. Sprinkle Foxglove Beardtongue seed on top of the soil. Then, press the seed into the soil with your thumb. This will ensure there is good contact with the soil without burying the seed. Foxglove Beardtongue seeds need exposure to sunlight to germinate.
  3. Place the container in a location that receives morning sun and afternoon shade. This is important, as the morning sun will help break the dormancy of the seed. But the Spring-time temperatures in the morning won’t dry out the soil. This improves germination rates.
  4. Keep the soil and seed moist. Use a pump sprayer or spray bottle to mist the soil when needed. Take care not to wash/bury seed.
  5. Seeds will generally germinate within a few weeks in Spring.
  6. Thin or separate seedlings. Thinning seedlings is an important step, as when seedlings grow close together they stay small.
Foxglove Beardtongue Seedlings, several weeks after germination. And ready to be thinned out!

How to direct sow Foxglove Beardtongue seed

Direct sowing Foxglove Beardtongue seed is easy. It will work best on bare, disturbed areas. Just scatter seed where you would like the plants to grow. Then, walk over the seed to press them into the soil. Seed will germinate in Spring once temperatures begin to warm up.

Time to establish / bloom from seed

You can expect Foxglove Beardtongue to bloom it’s second year when grown from seed. I’ve seen just about every plant I’ve germinated bloom in it’s second year as long as it was in full sun and transplanted before Winter.

But the first year of a Foxglove Beardtongue’s life will just be the basal rosette leaves, with no stalks.

Is Foxglove Beardtongue invasive?

Foxglove Beardtongue is not invasive or aggressive. Foxglove Beardtongue will spread via self-seeding and via clump-expansion from it’s rhizome roots. But it will not spread ‘far and wide’ via runners like other plants such as Obedient Plant and Bee Balm. So, outside of a bit of self-seeding, Foxglove Beardtongue will not spread.

And remember, Foxglove Beardtongue is not a weed. It is a native plant that belongs in the North American ecosystem.

Wildlife, Pests, and Diseases associated with Foxglove Beardtongue

Pollinators

Foxglove Beardtongue primarily attracts long-tongued bees such as honeybees, bumblebees, Mason, Leaf-cuters, and Miner Bees. It can also attract various butterflies, sphinx moths, and hummingbirds. But in my experience you will mainly see bees on the flowers.

Pests

Occasionally aphids will feed on the stalks. It is rare, but it can happen. Aphids do not cause significant damage to the plant, and are only cosmetically unsightly.

Aphids on the stalk of Foxglove Beardtongue

I have also observed gypsy moth caterpillars on the foliage.

Gypsy Moth on Penstemon digitalis

Deer and Rabbits

Many sources list Foxglove Beardtongue as deer and rabbit resistant. That does appear to be the case once the foliage reaches a certain age within the growing season. But young, freshly emerged foliage can be browsed by deer and rabbits, as evidenced by my photos below.

You can see in this photo where deer or rabbits have browsed the foliage of Foxglove Beardtongue

Note that the plants recovered without issue. So, while Foxglove Beardtongue may not be preferred by herbivores, it is not immune to browsing by deer and rabbits.

Foxglove Beardtongue Toxicity

There is scant information in my resources for Foxglove Beardtongue toxicity. After searching high and low for any reference to Foxglove Beardtongue being toxic or edible, I found a single source from Colorado State University highlighting the potential for selenium poisoning to horses/hoofed animals if the Foxglove Beardtongue is “grown in selenium rich soils[6].

But all my normal resources for toxic plants had absolutely no reference to Foxglove Beardtongue, Penstemon digitalis. The ASPCA does not have it listed as being toxic, it is absent from the reference book Poisonous Plants of the Southern United States. So, after checking this many sources, I cannot find any evidence that Penstemon is toxic to dogs or cats. [7] [8] [9]

So, despite the fact that I can find no evidence that Foxglove Beardtongue is poisonous, I don’t recommend you eat it. It is always good to be cautious when it comes to plants, and if you are not sure if something is safe to eat, then you shouldn’t eat it. But I can’t find any evidence that Foxglove Beardtongue harms dogs or cats.

Disease

In general native plants are not significantly effected by disease. And Foxglove Beardtongue is no exception, it is not significantly effected by disease.

Where you can buy PLANT

Foxglove Beardtongue is not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.

Where to buy seeds

We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)

Uses of Foxglove Beardtongue

Garden Uses

Foxglove Beardtongue is a great addition to any formal flower bed, perennial garden, border garden, or any wildflower meadow or prairie. It’s showiness, erect shape, and interesting foliage make it versatile in a variety of garden settings. The fact that the basal leaves are semi-evergreen give Winter interest to any flower bed.

Cut Flower

Due to the long blooming period, Foxglove Beardtongue is a good cut flower. In addition to a cut flower, I’m going to be trying the stalks in dried arrangements this year.

Companion Plants

Since Foxglove Beardtongue is adaptable it can pair nicely with a wide variety of plants. Some companion plants that bloom concurrently with Foxglove Beardtongue would inclue:

If you are trying to get non-stop color in a flower bed, some flowers that bloom after Foxglove Beardtongue but share similar growing preferences would include the following:

Varieties of Foxglove Beardtongue (Penstemon)

Due to how beautiful Foxglove Beardtongue is, efforts have been made over the years to breed new varieties and colors. There are numerous cultivars and hybrids of Foxglove Beardtongue available. Some of which include the following;

  • Blackbeard Penstemon
  • Dark Towers Penstemon
  • Dakota Burgandy
  • Husker Red
  • Mystica
  • Pocahontas
  • Purple Penstemon

Many of these breeds of Penstemon can be bought at large garden centers that don’t normally deal in Native Plants. But, since pollinators rely on UV Light to locate plants, know that purchasing a different colored Penstemon plant could confuse the pollinators, and you may not attract much wildlife.

If you would like to have more colors of Penstemon, it is best to purchase other species such as Hairy Beardtongue for a beautiful purple variety.

Medicinal Uses

Penstemon Digitalis was not used medicinally by Native Americans. At least, I cannot find any source citing this plant as having any medicinal, edible, or other use. There are other uses of Western species of Penstemon, but not for Foxglove Beardtongue specifically.

Find more Native Plants here!

References:

[1] – Keck, David D. “Studies in Penstemon VIII A Cyto-taxonomic Account of the Section Spermunculus.” The American Midland Naturalist 33.1 (1945): 128-206.

[2] – Wolfe, Andrea D., et al. “Phylogeny, taxonomic affinities, and biogeography of Penstemon (Plantaginaceae) based on ITS and cpDNA sequence data.” American Journal of Botany 93.11 (2006): 1699-1713.

[3] – Thomas, Patricia Ann. The function of insect trapping by Penstemon digitalis and Cirsium discolor. Diss. University of Illinois at Urbana-Champaign, 1988.

[4] – National Poison Control Center, Digitalis, Foxglove. Retrieved 01JAN2022

[5] – Lindgren, Dale T., and Daniel M. Schaaf. “Influence of seed stratification and seed age on emergence of Penstemon.” HortScience 39.6 (2004): 1385-1386.

[6] – Guide to Poisonous Plants, Colorado State University.

[7] – Toxic and Non-Toxic Plant List – Dogs, American Society for the Prevention of Cruelty to Animals. Accessed 01JAN2022

[8] – Miller, J. F., et al. “Poisonous plants of the southern United States.” Poisonous plants of the southern United States. (1980).

[9] – Poisonous Plants to Livestock, North Carolina State University Extension. Accessed 01JAN2022

[10] – Penstemon, North American Ethnobotany Database. Accessed 01JAN2022

Joe Foster

Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over six years. I hope to share some of my knowledge with you! Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!

Recent Posts