Penstemons Merit More Attention

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Penstemon 'Pensham Laura'

In the Trial Gardens at the University of Georgia, we look at dozens of echinaceas, heucheras, hibiscus, iris and most of the popular genera. For good reason, that is what people are buying — and any data is good data. However, we also evaluate lesser-known genera such as pulmonaria, drimiopsis, silene and penstemon. The latter genus is exceedingly popular in many European countries, reasonably well known in the western U.S., but not as much in the East. The only ones that seem to receive attention are the P. digitalis types, best represented by the ‘Husker’ name, yet breeders are working on them and growers have numerous options from which to choose. Grower information is available through brokers, breeders and young plant growers. All the plants mentioned below can readily fit into an existing perennial program.

In the landscape, most penstemons in the East generally only persist for three to four years. It is just the nature of the plant. Check hardiness ratings, because many are using genes from Southwestern natives and may not be sufficiently hardy in your region. As always, it takes time for retailers to embrace lesser-known plants — but let’s not ignore this excellent plant simply because we are awash in others.

Recommended Penstemons
I asked my students, Christian Fox and Macy Hall, to evaluate our penstemons based on their landscape performance, and come up with those they would recommend to their non-gardening friends. Here are a few we need to be putting in front of people.

The Phoenix series: Upright, about 2 to 2½ feet tall, flowers in many colors. Bred by Syngenta Flowers. (Zones 6 to 8)

We have rated ‘Phoenix Magenta’ highly, although red and pink have also been good. Eight colors are available. The large gloxinia-like flowers are particularly attractive at retail.

The Pensham series: Upright, smaller flowers, excellent longevity. (Zones 6 to 8)

The Penshams were bred by U.K. breeder Edward Wilson, who developed more than 50 named plants in the series. We received ours from Blooms of Bressingham. They are more persistent than other penstemons we have tried. The best has been ‘Pensham Laura,’ but ‘Pensham Amelia Jane,’ with its bright red flowers, is excellent as well.

The Polaris series: From Green Fuse, bred by Florensis. (Zones 5 to 8)

Easily available through many wholesale sources, there are at least three colors in this series with more coming. Large flowers, strong stems and good weather tolerance make this series well worth considering. We were most impressed with ‘Polaris Purple.’

Penstemon ‘Sweet Joanne’: From Blooms of Bressingham, bred by Dale Lindgren, University of Nebraska. (Zones 6 to 8)

The plants are hybrids of P. mexicali, so they have hybrid vigor and an upright habit. The soft pinkish-mauve flower color is subtler than many others but shows up well in the landscape, nevertheless. Plants are 2 to 2½ feet tall and provide weeks of excellent performance.

Penstemon ‘Red Riding Hood’ and P. ‘Iron Maiden’: Excellent upright habit, bright colors. (Zones 5 to 8)

I put these in because the flower colors are like magnets to shoppers, to say nothing of butterflies and hummingbirds. They are seed-propagated and may not be easy to find. Since they are not really part of a series, growers tend to shy away from them, but they are truly wonderful.  GG

Allan Armitage (allan@greenhouse grower.com) is a professor in the Department of Horticulture at the University of Georgia, Athens, Ga.

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