New Penstemon From Darwin Perennials

Darren Barshaw, Product Representative­—Darwin Perennials

The best part of my job is showcasing perennials that solve problems for our customers and their clients. Whether that’s a product that finishes faster, provides more disease resistance or performs better in the landscape, the new perennial breeding is helping our industry move forward.

With a class like penstemon—which checks so many boxes for consumers in terms of being pollinator friendly, easy to maintain and versatile in color—Darwin Perennials has spent the last several years trialing for ways it can benefit our grower customers. All our research has paid off with the launch and expansion of three series of penstemon to cover multiple garden heights for designers, plus adding modern color and reliability for marketability.

For 2026, Penstemon barbatus Rock Candy introduces a new Coral and has improved its Pink variety. Rock Candy is sweet as candy, but tough as nails! It’s your go-to border penstemon with compact flower spikes.

Brand new for spring sales are two series on the rise: Penstemon Mountain Treats is a hybrid launching as the mid-height and vigor option with five colors to choose from. All are vibrant and large-size blooms—perfect for hummingbird action. Penstemon Summit Sweets in Ruby and Purple has Zone-5a hardiness and grows tall in the landscape while being manageable at retail. It makes a fantastic thriller in mixes.

With so many choices—and you should grow them all for a well-rounded assortment—it’s great to know that the experts at Darwin Perennials can support your production with helpful guidelines and recommendations for success.

All three of our penstemon series are first-year flowering for simplified scheduling and they can all be grown alike. These new penstemon have the benefit of shorter crop times, which can increase your margins for perennial sales. Below are some additional tips to get the best products to market.

Propagation information
For spring sales around Week 18, you can use an unrooted cutting input. Stick the cutting Week 1 into your liner of choice. A rooting hormone is recommended at a rate of 500 PPM IBA. We base this information on a 72 liner and it takes roughly eight weeks to finish the liner and nine weeks to finish a 2.5-qt. pot. 

Apply one pinch in the liner stage. A low mist is needed with a root zone temp around 70F (21C). Do not oversaturate the rooting media.

Finishing
Penstemon are long-day facultative, meaning they need to accumulate light hours to bloom. Extending your daylength with lighting will bring them into bloom earlier; 12-hour days are recommended. Watch your watering—penstemon like to grow on the dry side—ideally a 2.5 to 3 on the moisture scale. Allow media to dry moderately between watering. Your media pH should range from 5.8 to 6.2. A preventive drench of a broadspectrum
fungicide is also recommended and scout for spider mites and thrips.

Finishing temps
Nights: 55 to 70F (13 to 21C)
Days: 60 to 80F (15 to 27C)

As mentioned above, the Mountain Treats and Summit Sweets series are more vigorous and taller forms of penstemon. A 2.5-gal. perennial
program works if you can move them quickly or I recommend a 1.5-gal. or 10-in. color pot for best presentation at retail. These two series also work well as thrillers in a combo pot. They can be marketed at retail for the home cutting garden segment as well due to their tall, impressive stems.

All of the Darwin Perennials penstemon will bloom May through July and attract the bees and hummingbirds to their flower show. Be sure to offer all of the options, asconsumers continue to show interest in colorful perennials. GT

Crop scheduling