How To Grow And Sell Penstemon

A hardy variety, Penstemon xmexicali 'Sweet Joanne' has large, long-lasting flowers.

Penstemon is an overwhelmingly diverse genus with approximately 250 different species. This genus includes plants that are evergreen, deciduous, shrubby, tall and low-growing. Also known as beard tongue, penstemon exhibits tolerance of a wide range of climates. Most penstemon are native to North and Central America, which encompasses the dry California climate, the higher altitudes of the Rocky Mountains, the Pacific Northwest, the eastern United States and some parts of Mexico.

The common thread among cultivars of this genus is their beautiful tubular, two-lipped flowers. Gardeners love that they attract hummingbirds and other pollinators. Flowers are borne on upright spikes held above mounding foliage. The blooms tend to have pale, speckled or striated interiors. Some have a striking white throat that contrasts well with the colorful outside. Lance-shaped leaves are another shared characteristic. There is bright-green, blue-green and even deep burgundy-red foliage found throughout this genus.

Popular Picks

One popular group is the tender types. These penstemon boast large, dramatic blooms in an array of vivid colors, and their habit is normally taller and more upright, which is ideal for the middle or back of the border. They also tend to have glossy green foliage and can be used as the centerpiece in mixed containers.
These typically flower for a long time, from early summer through the mid-late summer. Some of the most popular tender varieties and hybrids include: the Phoenix series, ‘Pretty Petticoat,’ ‘Ruby’ and ‘Sour Grapes.’

The species Penstemon digitalis includes the Perennial Plant Association’s Perennial Plant of the Year from 1996, Penstemon ‘Husker Red,’ which is famous for its pronounced red foliage. This variety is widely available and produced from seed or unrooted cuttings. Some newer varieties such as P. ‘Dark Towers’ and P. ‘Prairie Twilight’ are patented, vegetatively produced varieties with excellent garden performance. They are considered to be upgrades to ‘Husker Red.’

The digitalis species is typically hardy to USDA Zone 3, and while ‘Dark Towers’ is hardy to Zone 3, ‘Prairie Twilight’ is hardy to Zone 4. Other more common, hardy species include P. ×mexicali, P. barbatus, P. hirsutus, P. pinifolius, P. schmidel, P. smallii and P. strictus. P. pinifolius ‘Meresa Yellow’ is a unique variety because its tubular flowers are uncommonly yellow.

General Culture Tips

Depending on the species, there are spring-blooming penstemon and summer-blooming penstemon. The tender varieties usually bloom early through mid-summer. Hardy types typically bloom in late spring through early summer. Once flowering is complete, it is recommended to remove long flower stalks and prune them down to the base of the foliage. This helps improve their winter survival. Mulching also increases the chance of winter survival if the gardener is located in a mild zone, such as Zone 7 or colder.  

When growing penstemon in pot production for commercial greenhouse sales, the pH target should be between 5.8 to 6.5, and EC should not be higher than 1.5 mmhos/cm, as these plants are not very heavy feeders. In the Pennsylvania trial garden at Green Leaf Plants, growers target about 100 to 150 ppm nitrogen constant liquid feed, and penstemon respond well to this range.

The best thing is to avoid overwatering and be sure to provide good air movement. Good airflow in humid climates is beneficial. Most penstemon prefer fertile, well-drained soil and will not tolerate a wet root system. Penstemon also prefer the high-light conditions of spring and summer but do not necessarily require long days to flower. The crop can be finished at temperatures of 55°F to 65°F at night and 65°F to 80°F during the day.

Some varieties that are native to dry desert or alpine areas can be quite finicky if the grower is located in another climate. Germination can also be a challenge for some seed species and varieties. It is best for a beginner to seek out varieties that are produced and distributed on a large scale. There is a wide variety of commercially available species and hybrids.

Aphids have been known to attack the flower buds and stems, and a severe aphid infestation can result in deformed buds and flowers. Powdery mildew can be an occasional nuisance in late summer. Stem rot is also a problem when plants remain wet for long periods.

Crop Production By Cultivar
Penstemon can be propagated by seed, cuttings and division. Most tender varieties do not require vernalization to flower. Liners can be purchased and transplanted in the early mid-spring months for flowering plants in late June through July. Unrooted tip cuttings of many tender hybrids can be stuck in late winter through early spring. They can be grown outside once the danger of frost has passed. Growth regulators may be beneficial for taller tender species and hybrids. Staking may be beneficial if growing outdoors.

Some of the hardy varieties and hybrids that do not require vernalization can also be purchased in liner form and transplanted in spring for blooming plant sales in early to mid-summer. This includes the P. ×mexicali cultivars such as ‘Pike’s Peak Purple’ and ‘Sweet Joanne.’ Unrooted tip cuttings can be started in late winter through early spring. The new Carillo series, which is available in rose and purple with white throats, is produced from seed and will flower in the first year.

The P. ×mexicali cultivars are hardy to Zone 5 and are popular with growers and gardeners because of their floriferous nature, well-branched plant habit and ease of growing over a large range of climates.

Other hardy cultivats in the P. barbatus, P. digitalis and P. hirsutus species, such as the popular ‘Prairie Dusk’ and ‘Husker Red,’ perform well when liners are planted in late summer or early fall and the plants are allowed to bulk in the pot prior to vernalization. Many of the late-spring-blooming, hardy types can be propagated in late summer by small divisions or basal cuttings rather than tip cuttings. Cuttings are rooted then transplanted into the final sales container before the onset of cool weather.

Depending on the location of the grower, overwintering outdoors may be an option for these hardier types, as long as there is not constant temperature fluctuation below and above freezing. If overwintering is desired in a region where outdoor vernalization is not an option, keep plants in a cold greenhouse set at 35°F to 38°F and allow plants to flower naturally the following spring season.  

A new Penstemon schmidel series called Riding Hood is fully hardy to Zone 5 and grows to a maximum height of 22 inches. There are six colors in the series. Basal cuttings can be started in winter and liners can be planted in spring for finished material in early summer. Because the Riding Hood varieties can be flowered the same year from unrooted cuttings and have a desirable, compact habit, this series is attractive to many commercial growers.

With the myriad of choices within the genus, growers can select the best varieties to grow for their region of the country and level of expertise. Gardeners can enjoy the flexibility of their use whether it is in the perennial border or as a specimen annual in the border or mixed container. All in all, the fantastically diverse penstemon genus has something for everyone.  GG

Leave a Reply

Latest Stories
America In Bloom Project

August 29, 2016

Your Chance To Help America In Bloom As It Celebrates I…

America In Bloom is launching a fundraising campaign to help the group continue its mission of creating beautiful and vibrant communities across the country.

Read More

August 29, 2016

Does Point-Of-Sale (POS) Make A Difference for Plant Re…

When Greenhouse Grower RETAILING asked plant retailers about their plant pricing techniques, we also asked if they use POS or not. We decided to take a close look at where these two groups differ:

Read More
Griffin Logo

August 29, 2016

What You Should Do At The Griffin Expos, Massachusetts …

The first of the fall Griffin Expos takes place this week in West Springfield, MA, August 31 and September 1, 2016. A Lancaster, PA, Expo will take place next month. If you’re heading to this distributor show, make sure you check out these highlights: White Elephant Sale Each year, Griffin clears out its branch warehouses by holding a sale of its closeout and overstock items. The discounts are deep, and the competition for the items are fierce. “Once items are gone, they’re gone. So, that first hour or so is kind of like ‘the running of the brides’ at Filene’s,” says Tracey Gorrell, Marketing Communications Lead at Griffin. On-Site Experts Griffin offers opportunities to connect face-to-face with industry experts and get answers, tips, and advice catered to your unique needs and interests: The GGSPro team is available to field your questions; and 150 manufacturers, breeders, and young-plant producers can discuss […]

Read More

August 29, 2016

Fire Damages Swanson Nursery

Fire crews were called to Seattle-based Swanson’s Nursery in the middle of the night on August 22, the Ballard News Tribune reported. The fire, likely started by an “electrical issue,” destroyed bathrooms and a seminar room, Retail Manager Eric Nordstrom told the news outlet. Smoke damage was more extensive, however. Swanson’s President, Brian Damron says the fire also reached a storage area and utility room. A fire department spokesman says the fire broke through the greenhouse walls, and that part of a wooden wall had to be removed so the crew could reach the flames. The store’s café resides next to the damaged area, and is temporarily closed. It’s an important part of Swanson’s off season revenue strategy. The store is working with a timeline of repairs with its insurance company so it can determine when the cafe can reopen, the news outlet reports. The fire was out relatively quickly once […]

Read More
North Creek Nurseries Feature Image

August 29, 2016

North Creek Nurseries Unites Horticulture With Sustaina…

The team at North Creek Nurseries, Greenhouse Grower’s 2016 Operation Of The Year, leads the way in implementing ecologically responsible practices that will sustain the future of growing.

Read More

August 28, 2016

BioWorks IPM/Sustainable Practices Scholarship Goes To …

Schaller, a senior at the University of Arizona in the Plant Sciences Department, is interested in ornamental and floriculture crop breeding and crop physiology.

Read More
Next Generation

August 27, 2016

Australia Launches Initiative To Ignite A New Generatio…

Hort Innovation Chief Executive John Lloyd says the goal is to identify and build future industry leaders at all stages of their career through investment in a host of new initiatives.

Read More
Penn State University Trial Day

August 26, 2016

How Greenhouse Growers Can Broaden Their Horizons

Allan Armitage says you can learn new ideas to help your business when you get out to visit plant trials and other growers.

Read More
Albert Grimm, Jefferys Greenhouses

August 25, 2016

7 Ways Albert Grimm Strives To Be An Effective Leader

Grimm, Greenhouse Grower's 2016 Head Grower Of The Year, tries to live by the "Seven Habits Of Highly Effective People” from author Stephen R. Covey.

Read More
Tidal Creek Growers

August 25, 2016

Maryland-Based SunMed Growers Nabs Cannabis License

The company was one of 15 licensees selected by the commission out of a pool of 145 grower applicants to receive one of the license pre-approvals.

Read More
GrowSpan Light Deprivation Greenhouse

August 25, 2016

New Light Deprivation Greenhouses Help With Light Manag…

The GrowSpan light deprivation greenhouse from Growers Supply is outfitted with a blackout system that provides growers with control over the light cycle.

Read More
Albert Grimm GOY feature

August 25, 2016

Up Close And Personal With Head Grower Of The Year Albe…

According to Grimm, Greenhouse Grower’s 2016 Head Grower Of The Year, the key to being a successful grower is educating and inspiring yourself, your staff, your customers, and the next generation of growers.

Read More
To offer consumers an attractive crop, Local Appetite uses high tunnels to grow cherry tomatoes

August 24, 2016

New Food Safety Compliance Resource Available For Green…

The FSMA Wizard from Registrar Corp makes it easy for food producers, including greenhouse vegetable growers, to determine their possible requirements under the Food Safety Modernization Act.

Read More
Cannabis Structure

August 23, 2016

5 Factors To Consider In Your Cannabis Structure

Along with the size and specs of your greenhouse, it's also important to focus on ventilation, light deprivation, benching, irrigation, and odor control.

Read More
Penn State Plant Bud

August 23, 2016

AmericanHort Is Helping Plant Importers Adjust To New R…

A report from Craig Regelbrugge at AmericanHort says the government is implementing a streamlined system for imports, in which all required data will be submitted electronically through a single window.

Read More

August 23, 2016

Kick Spring Sales Up A Notch With 18 New Plant Introduc…

It’s time to look forward to the spring season and what plants will get your business off to the right start. These 18 new cultivars have all the traits of good breeding — uniform habits, bold colors, showy blooms, good vigor, and excellent branching.

Read More
Bees And Pesticides

August 23, 2016

Studies Offer Conflicting Views On Neonic Effect On Bee…

How much exposure to neonicotinoids do bees need before their health becomes affected? That’s the question two research teams look to answer.

Read More

August 23, 2016

Gardens Alive! Parent Company Buys Zelenka Farms

  Zelenka Farms, which has been in Chapter 11 bankruptcy, says LM Farms, which owns Gardens Alive!, has purchased the company and all of its assets. BFN Operations LLC and its affiliated entities, d/b/a Zelenka Farms, operated one of the largest wholesale nurseries in the U.S. Its products include shrubs, trees, perennials, roses, and groundcovers. The owners of Gardens Alive! have successfully purchased several other companies from bankruptcy and are experienced nursery managers. Niles Kinerk, Chairman of LM Farms, stated that “the opportunity to purchase Zelenka Farms assets and to continue the turnaround that is well underway is exactly the kind of opportunity that we look for. We understand the efforts of the management team led by Eric Ek and others have been successful, and we will support the management team in the coming months and years.” Zelenka Farms operates its six facilities across the key growing regions in the […]

Read More
[gravityform id="35" title="false" description="false"]