There are seemingly endless reasons to add native plants to your garden. They’re easy to care for, benefit insects and wildlife, and work well in mixed plantings. If you’re unsure where to start with native plants, consider penstemon.
These flowering perennials produce gorgeous bell-shaped flowers in the spring and summer, filling your garden with color and attracting pollinators. And since there are hundreds of penstemon species and varieties, these plants can fit in front of porches or in the backdrop of native plantings.
I’ll introduce you to some popular penstemon plants and explain how to care for them properly. Plant one of these flowers in your garden, follow my advice, and don’t be surprised if you become hooked on these gorgeous perennials.
Penstemon Overview Penstemon spp.
What Is Penstemon?
Also known as beardtongue, penstemon is a large group of flowering perennial plants native to North America. Since these plants range in height and color, you can find a species to fit in nearly any garden.
Penstemon plants offer insects both pollen and nectar.
Gardeners throughout the United States love penstemon plants for their beautiful, long-lived flowers. Most penstemon species bloom for multiple weeks in the late spring and summer, providing insects with pollen and nectar after many spring bloomers fade. If you want to watch bees, butterflies, and hummingbirds flock to your garden, this plant is for you!
Penstemon plants first produce rosettes of leaves that lie close to the ground. As the plants mature, they send up multiple stems covered with elongated leaves. Eventually, the plants produce flower stalks covered in tubular flowers. Both flower color and plant height vary by species and variety, so shop around until you find one that fits into your garden.
Opting for a penstemon native to your area enhances its adaptability to your local climate.
All types of penstemon plants are native to North America, but the exact native range varies between species. Some penstemons are native to the rainforests of the Pacific Northwest, others originate in Mountain West meadows, and others call the South home. Choosing a penstemon native to your region helps decrease maintenance and increase the plant’s suitability to your climate.
Benefits to Wildlife
Adding native plants to your garden can be a boon for various insects.
These native plants benefit a wide range of insects, making them a valuable addition to your garden. Their tubular flowers provide nectar and pollen to pollinators, including butterflies, moths, and bees. Beneficial predatory insects like ladybugs, green lacewings, and hoverflies also flock to these plants to feed.
Penstemon plants also serve as host plants for butterflies and moths like the Chalcedony midget moth, Chalcedon checkerspot, and Baltimore checkerspot. This means the adults lay their eggs on the penstemon plants, and the larvae feed on the plants’ leaves.
Penstemon plants grow well in the ground and containers. Since they don’t compete well with more vigorous plants, give them enough space to grow.
Select an appropriate spot and plant the seedlings in the soil.
When looking for penstemon plants at nurseries, remember people often refer to them by the common name beardtongue. So, if you can’t find any penstemon plants, look for beardtongue!
Since there are so many different penstemon species and varieties, plants may only contain a label with their cultivar name rather than their species. If you can’t find the species name, look at the tag for the hardiness zone and height information.
Once you find a penstemon suitable for your climate, it’s time to plant it at home. Spring is the best time to transplant penstemon. Wait for the last frost to pass, find a suitable location, then plant the seedlings in the ground. Although mature penstemon plants don’t require lots of water, keep newly planted penstemon moist the first couple of weeks after planting.
Growing from Seed
Most penstemon seeds require cold exposure, also called cold stratification.
Growing penstemon from seed is a great option to produce many plants or grow a variety you can’t find in local nurseries. You can purchase seeds in stores and online or collect seeds from plants growing in your garden (just remember never to collect seeds from prohibited areas). If you collect your own seed, store it in a cool, dry area for up to five years.
One planting option is direct seeding. Most penstemon seeds need a period of cold stratification—that’s gardener-speak for “they need exposure to cold.” To give them the chilly temperatures they need, plant the seeds in your garden in the late fall or winter before cold weather arrives. Select a well-draining area, sprinkle the seeds, cover them with half an inch of soil, and water well. The seeds will sprout the following spring as long as they remain moist.
Another option is to stratify the seeds in the winter and then plant them in containers to later transplant. Place the seeds in between two pieces of moist paper towel, set them in a plastic bag, then place the bag in a refrigerator for at least a week.
After stratifying the seeds, plant them in seedling containers filled with moist potting mix. Place them somewhere between 50-70°F until they germinate. Once the seeds sprout, place them in a greenhouse or indoors under a grow light.
How to Grow Penstemon
If you select a penstemon well-suited to your climate, these plants are easy to grow. Once established, they require little or no maintenance to remain healthy.
Penstemon plants generally prefer full sun but can handle some afternoon shade.
Most penstemon plants grow best in full sun but can handle a few hours of afternoon shade. So don’t worry if larger plants in a mixed planting provide a bit of shade.
Directly watering the plant at its base rather than overhead ensures dry foliage, mitigating disease risks.
Once penstemon plants are fully established, they can tolerate moderate drought. Since they’re sensitive to wet soil, it’s better to keep soil on the drier side. Watering the base of the ground is better than overhead watering since it keeps the foliage dry and prevents disease.
Although mature plants can handle drought, recent transplants don’t have strong root systems. Limit plant stress by keeping the soil moist for the first two weeks after transplanting.
To ensure their well-being, avoid planting them in areas prone to waterlogging or with poor drainage.
If you’re dealing with poor soil, don’t worry! Not only do penstemon plants grow well in nutrient-poor soil, but they even prefer it to rich soil. Penstemon plants growing in rich soil tend to develop tender vegetation that’s less tolerant of temperature changes, wind, and other environmental stressors.
While they don’t need a lot of nutrients or organic matter, they cannot tolerate wet soil. Avoid planting them in low-lying areas or poorly draining soil.
Temperature and Humidity
When considering these plants, it’s essential to check each species’ hardiness zone.
Since the penstemon genus comprises hundreds of species, their heat and cold tolerance varies. While all beardtongue plants tolerate temperatures between 30°F-80°F, specific species can handle hotter and colder temperatures. Look at each species’ hardiness zone if you live in an area with especially cold or warm winters.
As far as humidity goes, these perennials aren’t picky. Most species tolerate high to low humidity.
Penstemon plants flourish without the need for fertilizer, which can actually be detrimental to them.
One of the best parts of planting penstemon plants is they thrive without any fertilizer. Too many nutrients can actually harm the plants, so avoid applying nutrient-rich compost or a fertilizer with a high NPK ratio.
Removing fading flower stalks not only tidies up the plants but also stimulates new bloom production.
One of my favorite aspects of these native plants is how low-maintenance they are. And this makes sense when you consider how they originated and evolved in the United States. I advise choosing a penstemon species native to your region to avoid maintenance like pruning and watering.
While penstemon plants will grow well without your help, you can prune and deadhead the plants to keep your garden tidy. Remove spent flower stalks when they begin to wither and fade in color. Not only will this keep the plants tidy, but it will also encourage them to produce new blooms.
Pruning the plants’ stalks to a few inches above the ground in the late fall allows you to tidy up before winter arrives. However, I leave my penstemon plants as-is throughout the winter to avoid disturbing overwintering bees and caterpillar pupae.
Since penstemon plants readily produce seeds, you can collect and plant the seeds to form new plants. However, propagating the plants by division or cuttings allows you to create mature plants more quickly. These methods also allow you to propagate hybrid penstemons.
To propagate penstemon plants, find healthy, pliable stems without flowers.
You can propagate penstemon plants from herbaceous cuttings in the spring through fall. You’ll have new plants to share with friends or expand your garden by rooting these cuttings.
- Locate healthy, vegetative stems. Look for pliable rather than woody stems without any flowers.
- Use a sharp and sanitized pair of pruning shears to cut off the top four inches of the stems, ensuring each cutting has at least six leaf nodes.
- Use your hands to gently remove the leaves from the bottom two inches of each cutting.
- Dip the ends of the cuttings in rooting hormone.
- Set the bottom inch of the cuttings in a container filled with a moist and well-draining potting mix. Place a humidity dome or plastic bag above the cuttings to trap humidity, but ensure this covering isn’t touching the cuttings’ leaves.
- Keep the cuttings in a warm location out of direct light and water to keep the soil moist.
- Depending on the temperature and species, the plants will form roots in three to six weeks.
To divide them, gently pull the plant apart at the stems and roots.
Dividing penstemon plants involves breaking large plantings into multiple smaller clumps. Therefore, only divide large, healthy, mature plants. The best time to divide penstemon is in the late winter or early spring as plants resume growth.
Start by digging up the entire plant’s root ball and shaking off excess soil. Each “plant” will consist of multiple leaf rosettes and accompanying root systems. Your goal is to divide each of these rosettes so you’re left with multiple separated plants.
Grab either side of the plant and gently tease it apart to separate the roots and stems. If you’re having difficulty breaking up the plant, you can use a knife or pair of pruning shears to cut through the plant material.
Popular Penstemon Species and Varieties
With hundreds of penstemon species and even more varieties, you have lots of plants to choose from! I’ve included some of my favorites below to help you start your search.
Rocky Mountain Blue Penstemon (Penstemon strictus)
This penstemon, thriving in states like Utah, Colorado, and Wyoming, showcases striking blue flowers.
As you probably guessed, this penstemon produces stunning blue flowers and flourishes in Rocky Mountain states, including Utah, Colorado, and Wyoming. It’s extremely hardy and can tolerate drought as well as cold temperatures. Since it grows 24-36” tall, it works well in mixed plantings.
Dazzler Blend Penstemon (Penstemon barbatus)
A fantastic choice for compact gardens, this variety typically stays less than 12 inches tall.
Also known as beardlip penstemon, this species is native to the mountains and meadows in the Southwest. The ‘Dazzler Blend’ variety remains under 12” tall, making it a great addition to small gardens.
Large-Flowered Penstemon (Penstemon grandiflorus)
These plants bear strikingly large, pale pink or purple flowers on their tall stems.
Native to prairies throughout the central and midwest United States, large-flowering penstemon is a showstopper. Plants grow to four feet tall and produce large pale pink or purple flowers atop their tall stalks.
Foxglove Penstemon (Penstemon digitalis)
This aptly-named species bears a strikingly close resemblance to foxglove blooms.
Many people say penstemon flowers resemble foxglove blooms, but this aptly-named species bears an extra close resemblance. It’s native to much of the eastern US and produces white or pale pink flowers.
Choosing a species well-suited to your area is essential to minimize issues.
As long as you choose a species well-suited to your area, you’ll deal with very few problems!
Like most vegetative plants, penstemon leaves are susceptible to attack from slugs and snails. If you start to notice small bites in penstemon leaves, these little mollusks likely came by for a snack. Keep an eye out for these critters and control them by hand-picking.
Two other problems to watch out for are fungal diseases like powdery mildew and downy mildew. These diseases are most likely to occur in damp, stagnant conditions, so remember to bottom water your plants and provide proper plant spacing.
Frequently Asked Questions
Penstemon grows well with other drought-tolerant native wildflowers, including coreopsis, coneflower, and yarrow. Mix these plants together to create a beautiful and beneficial garden.
Most penstemon plants only flower in the spring and early summer, so don’t expect blooms outside of this time. Other reasons for a lack of flowers include young plants, drought stress, and a lack of light.
Although penstemon plants are perennials, they’re relatively short-lived. Most penstemon species live three to seven years, even if you provide them with excellent care.
When you consider the penstemon’s beautiful flowers, hardy nature, and benefits to wildlife, it’s hard not to want to add one of these plants to your garden. Since you can find many different species, try planting a few different ones to see which plants flourish in your garden.