Large beardtongue (Penstemon grandiflorus)

Also known as: Large-Flowered Penstemon, Beardtongue penstemon, Large penstemon, Shell leaf penstemon

The large-flowered beardtongue (Penstemon grandiflorus) is a perennial plant that is considered endangered in certain regions of the United States, making it a rare sight in the wild. This plant produces striking large, tubular flowers in shades of pink or purple during late spring. It is known for its drought resistance and its ability to attract both bumblebees and hummingbirds.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Large beardtongue

Lifespan

Perennial

Plant Type

Herb

Plant Height

40 cm to 1.2 m

Spread

30 cm to 60 cm

Leaf Color

Green Blue

Flower Size

2.5 cm

Flower Color

Pink Purple Blue

Images of Large beardtongue

Quickly Identify Large beardtongue

Look for its large, showy, tubular flowers, which typically bloom from late spring to early summer. The plant has smooth, grayish-green leaves, and it can grow up to 3 feet tall.

Scientific Classification of Large beardtongue

Phylum

Vascular plants

Class

Dicotyledons

Order

Lamiales

Family

Plantain

Genus

Penstemon

Species

Large beardtongue

Planting and Growing of Large beardtongue

Care Difficulty

Easy

Watering Schedule

Every 2 days

Sunlight Requirements

Full sun

Sunshine Duration

4-6 hours

Ideal Temperature

65-75℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Ceramic

How to Water Large beardtongue?

Penstemon grandiflorus prefers a deep and thorough watering, ensuring that the water reaches the root zone. This effectively encourages the roots to grow deeper, providing stability and resilience. Allow the soil to dry between watering sessions to prevent root rot.

What are the symptoms of an underwatered Large beardtongue? ›

What should I do if my Large beardtongue is not getting enough water? ›

What are the symptoms of an overwatered Large beardtongue? ›

How to save an overwatered Large beardtongue? ›

What Are the Sunlight Requirements for Large beardtongue?

Sunlight Requirements: Full sun, Partial sun

Duration of light: 6-8 hours daily

Set in full sun to partial sun. Ideal light enhances photosynthesis, resulting in strong stems and brilliant flowers, optimizing the plant's energy and nutrient uptake.

What kind of light is best for Penstemon grandiflorus? ›

How can I ensure the plant gets its ideal lighting conditions? ›

What benefits does ideal lighting provide for this plant? ›

More About Sunlight Requirements Techniques→

What Is the Ideal Temperature Range for Large beardtongue?

Ideal Temperature: 65 ~ 75℉

For optimal growth, Penstemon grandiflorus prefers a temperature range between 65°F and 75°F. This range is conducive to its physiological processes, allowing for efficient photosynthesis and growth. The stability of this temperature range ensures that the plant can maintain its metabolic functions without stress, promoting vibrant blooms and healthy foliage.

What Soil is Best for Large beardtongue?

Soil type: Sandy loam, Loam

Soil PH: 6.5 ~ 7.5

Penstemon grandiflorus thrives in well-drained soil as it prevents root rot and allows for excellent aeration. Well-drained soil ensures that the roots of the plant do not sit in water, reducing the risk of fungal diseases and promoting healthy growth. This plant prefers soil with moderate nutrient levels. Excessive nutrients can lead to leggy growth, whereas moderate nutrients promote robust and compact growth, ideal for maintaining the plant's beautiful and natural shape. Penstemon grandiflorus does not require high levels of organic matter. Low organic content helps maintain a balance in soil moisture, avoiding excessive wetness which can be detrimental to the plant's roots.

How to Fertilize Large beardtongue?

Fertilizer type: Balanced

For Penstemon grandiflorus, the application of fertilizer should be done with precision. Use a balanced liquid fertilizer diluted to half strength, approximately 1 to 2 tablespoons per gallon of water. Apply this evenly around the base of the plant to avoid potential root damage.

How to Prune Large beardtongue?

Pruning Time: Spring, Summer

Begin by using clean, sharp pruning shears to remove any dead, diseased, or damaged stems. Focus on trimming about one-third of the plant's height to encourage new growth. Remove spent flower stalks down to the base to promote the next bloom cycle. Be cautious not to cut too deeply into the wood, as this could harm potential new buds. To shape Penstemon grandiflorus, cut the longest stems back, focusing on maintaining a natural, rounded shape. Make cuts just above a set of leaves, ensuring you are encouraging outward growth. This method not only maintains the plant’s aesthetics but also ensures proper air circulation within the plant structure, reducing the risk of fungal diseases. More About Pruning Techniques→

How to Propagate Large beardtongue plant?

Propagate Time: Late spring, Early summer

Start by collecting seeds from mature Penstemon grandiflorus plants. Clean the seeds carefully to remove any plant debris or remnants that might inhibit germination. It's advisable to stratify the seeds by placing them in the fridge for a few weeks to mimic winter conditions, which can enhance germination rates.

Select a healthy stem from the mother plant and cut it below a node using clean pruning shears. Remove any leaves from the lower half of the cutting to prevent rot and dip the cut end into a rooting hormone to promote root development.

Prepare a pot with a well-draining soil mix, create small holes, and insert the cuttings. Ensure the soil remains moist but not waterlogged to prevent rotting. Position the pots in a warm and bright area but away from direct sunlight to encourage root growth.

More About Propagating Techniques→

How to Repot Large beardtongue plant?

Repotting frequency: Every 2-3 years

Repotting your Penstemon grandiflorus is advised when roots start emerging from the drainage holes, indicating the plant is root-bound. The best times are during active spring growth or early summer, when the plant can best handle the stress.

Select a pot that is one size larger than the current one, ensuring it has adequate drainage holes. This prevents waterlogging, which your Penstemon grandiflorus dislikes, while giving room for root expansion, promoting healthier growth.

A sandy, well-draining mix mimics the natural environment of Penstemon grandiflorus, preventing root rot and promoting air circulation around the roots. It provides a balanced medium ensuring neither excessive dryness nor water retention.