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How to Plant, Grow, and Care for Penstemon (Beardtongue)

Pink and white Penstemon digitalis ‘Dakota Burgundy’ in flower.
Photo Credit
Alex Manders
Botanical Name
Penstemon spp.
Plant Type
Perennial Flowers
Sun Exposure
Full Sun
Soil pH
Acidic
Neutral
Slightly Acidic to Neutral
Bloom Time
Spring
Summer
Flower Color
Blue
Pink
Purple
Red
White
Yellow
Hardiness Zone
3
4
5
6
7
8
Special Features
Attracts Bees
Attracts Butterflies
Attracts Hummingbirds
Attracts Pollinators
Attracts Songbirds

What Is Penstemon? Meet the Tough Perennial with Trumpet Blooms

Lauren Landers
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Penstemon, or beardtongue, doesn’t just talk the talk—it blooms the bloom! I’ve grown these hardy native perennials for years, and they never fail to bring bold color, busy pollinators, and zero fuss. With their trumpet-shaped flowers and tough-as-nails attitude, penstemon thrives in dry, poor soil and full sun.

In this guide, I’ll share everything you need to know to plant, grow, and enjoy penstemon—plus a few tips from the garden beds that keep my neighbors’ tongues wagging.

What Is Penstemon? A Tough Native With Showy Blooms

Penstemon is one of the largest native plant genera in North America, with over 280 species commonly known as beardtongues. They get their name from the fuzzy, pollen-free stamen that resembles a little tongue—though it’s the trumpet-shaped blooms that truly stand out in the garden.

As a longtime gardener, I’ve found penstemon to be one of the most reliable perennials you can plant. These beauties come in all shapes and sizes—from low-growing alpines just a few inches tall to shrubby types that stretch over 8 feet. Most have woody stems and basal leaves that hold through winter, though a few are fully deciduous. Their drought tolerance and love of poor soil make them a favorite for xeriscapes and anyone tired of babying fussy flowers.

Want pollinators? Penstemon delivers:

A female Broad-tailed Hummingbird approaching a Rocky Mountain Penstemon flower stalk with upright wings against a dark background.
Hummingbird-approved! Credit: Susan Hodgson

In my own beds, I like to mix penstemon with other sun-loving perennials or mass them together for a bold, naturalized effect. Since they flower from late spring to early summer, they’re perfect for bridging that awkward gap between the tulips and the coneflowers. Just give them full sun—and skip the rich compost or you’ll end up staking floppy stems!

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Planting

Penstemon is usually grown from nursery starts, but it sprouts readily from seeds as well. Whether you grow penstemon from seed or started plants is up to you. But it’s important to note that penstemon may not bloom during its first year if you grow plants from seed! 

When to Plant Penstemon

The best time to plant nursery-started penstemon is in spring, after the risk of frost has passed. However, you can plant penstemon in summer if you water often, or in autumn at least 4 weeks before frost is expected.

If you want to grow penstemon from seed, direct sow the seeds outdoors in late fall after the ground has frozen, and allow the seeds to cold stratify through winter. You can also cold stratify penstemon seeds indoors in your fridge in spring, but this takes about 3 months!

How to Plant Penstemon

  • To plant penstemon plants, dig a hole that’s slightly larger than your plant’s root ball and locate the plant in the hole at the same depth it was growing in its nursery pot. Rather than adding compost or manure, simply fill the hole with soil, add mulch, and water well. If you’re growing multiple plants together, space penstemon at least 12 inches apart.
  • To plant penstemon seeds, weed and rake your planting spot level before the ground freezes in autumn. When the ground freezes, scatter penstemon seeds over the soil, cover the seeds lightly with straw or up to ¼ inch of soil, and water the seeds in. You’ll only need to water the seeds again when they sprout in spring.

Growing

While most plants grow better if you mix a bit of compost into the soil before planting, you can skip this step with penstemon! Well-draining flower beds are the best choice for most types of penstemon, but smaller alpine varieties can also be tucked into rock gardens or beds with sandy or gravelly soil.

Light

Although penstemon are relatively adaptable plants, they don’t tolerate shade and should only be planted in full sun locations that receive at least 6 to 8 hours of direct light per day.

Water

Penstemon are drought-resistant once established and can be especially good choices for xeriscaping. That said, these plants grow even better if they receive about 1 inch of water per week. However, it’s important not to overwater penstemon as they will quickly develop root rot in poorly draining or clay-heavy soils.

Fertilizer

Overly rich soil and overfertilization can cause penstemon to develop floppy stems and lots of leaves with minimal flowers. To avoid this, refrain from adding compost or manure to your soil when growing these plants, and lightly fertilize penstemon only once a year in spring or fall with a balanced, organic fertilizer.

Humidity

Penstemon can tolerate a range of humidity levels. However, if you live in a humid location, it’s doubly important to space penstemon well apart in the garden. Overcrowded conditions and high humidity can increase the risk of mildew issues!

Seasonal Care

There’s generally no need to prune penstemon, but deadheading old flowers can make your plants look more trim and encourage reblooming. If possible, avoid the temptation to prune old penstemon stems and leaves in fall as they provide extra protection to the plant’s roots in cold weather. These plants also don’t compete well with weeds and other plants, so it’s imperative to give them enough space in the garden and to weed flower beds regularly to prevent weeds from creeping in.

Propagation

Penstemon is a short-lived perennial that will sometimes self-sow and produce new plants without any effort. However, you can create more penstemon by dividing your plants, collecting seeds, or propagating new plants from cuttings.

  • To propagate penstemon from root division, dig up your plants in early spring and cut their roots into sections with a shovel, spade, or gardening knife. Make sure each section has a healthy clump of roots and leaves, and then replant and water the divided plants as soon as you can!
  • To propagate penstemon from seeds, allow penstemon flowers to dry on the plant. Then, shake the dried seeds into a paper bag. Plant the seeds in spring or fall using the tips above. This technique only works with native or heirloom-type penstemon and is not suitable for hybrid plants.
  • To propagate penstemon from cuttings, take 4- to 6-inch-long stem cuttings at a leaf node from healthy, non-flowering plants in spring. Remove the lower leaves on the cutting, dip the cut stem end in rooting hormone, and plant 1 inch deep in a premoistened substrate with added perlite or sand for drainage. Move the cuttings into bright, indirect light, cover them with clear plastic to boost humidity, and keep the soil evenly moist with regular misting until the plants have rooted and can be replanted on their own.

Types

Some types of penstemon are more cold hardy than others, so it’s wise to do a bit of research before selecting the best penstemon varieties for your garden. Remember, native types of penstemon generally offer the most benefits to pollinators, while hybrid varieties may be more colorful or disease-resistant, but they’re not recommended for seed saving! 

  • Common Penstemon (Penstemon barbatus): This penstemon can produce red, pink, or purple flowers and grow up to 5 feet tall.
  • Pine Leaf-Penstemon (P. pinifolius): Hardy in Zones 4 and above, aptly named pine-leaf penstemon features thin, needle-like leaves and bright red flowers that hummingbirds adore.
  • Foxglove Beardtongue (P. digitalis): Native throughout much of the Eastern United States, this penstemon variety serves as a host for several species of butterflies and attracts pollinators with its bright white blooms.
Close up of cluster of delicately colored Penstemon flower heads with bee flying nearby to pollinate
Bees adore the Penstemon flower heads! Credit: Nigel Jarvis
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Pests/Diseases

For the most part, penstemon is a pest- and disease-resistant plant that doesn’t struggle much in the garden. However, plants that are stressed by less-than-ideal growing conditions may develop issues like:

  • Pests like slugs and snails will sometimes target penstemon plants. Control them with hand-picking or DIY slug traps made with an old plastic cup and stale orange juice.
  • Root rot can occur if penstemon is grown in poorly draining gardens or watered too often.
  • Powdery mildew may settle onto penstemon leaves and flowers in humid and overcrowded gardens. To avoid this, water plants at the soil line and space them well apart!

Wit and Wisdom

  • Penstemon belongs to the Plantain plant family, which includes other perennial favorites like foxgloves, turtleheads, and snapdragons.
  • The interior of penstemon flowers are often a different color from the plant’s petals and serve as a “nectar guide” to make the plant more appealing to pollinators!
  • Certain types of penstemon were traditionally used by indigenous tribes to treat ailments like stomach pain and depression.
Flowers
About The Author

Lauren Landers

Lauren is a gardener, writer, and public speaker with over a decade of experience helping others learn about gardening, homesteading, and sustainable living. Read More from Lauren Landers
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