Top Five Flower Performers for Rocky Mountain Conditions

Echinacea Sonbrero Tres Amigos, photo courtesy of CSU

Colorado State University’s trial garden evaluates new perennial plant species and cul­tivars under the unique Rocky Mountain environmental conditions.  Plants are evaluated for plant vigor, uniformity, floriferousness, and tolerance to environmental and biot­ic stresses. The Perennial Trial program at CSU is designed to test newer perennial cultivars that have been introduced in the past three years or less. Entries in this trial are grown for three summers and two winters before they are switched out for new entries.

On November 20, 2020, a conference call was convened with CSU staff and the Perennial Trial Garden Subcommittee. The following is the list of winners selected as a “Top Performer” perennial.

“Top Performer” Perennials from the 2020 CSU Perennial Trial

Allium Summer Beauty, photo courtesy of CSU
  1. Allium ‘Summer Beauty’ (Allium lusitanicum) from Stonehouse Nursery, LLC

Soft lavender-blue flowers were prolific and brought strong flower power later in the summer. Flowers were relatively tall and held above the foliage for maximum show but had good structure and did not lodge. The plant was uniform and very attractive with glossy, green flat leaf blades.

Echinacea Sonbrero Tres Amigos, photo courtesy of CSU
  1. Echinacea ‘Sombrero® Tres Amigos’ (Echinacea x hybrida) from Darwin Perennials

Flowers were unique with an “evolution of color” that resulted in about three different shades of color during the season. Blooms were vibrant with a rich saturated color. Abundant flowers remained in bloom for a long time and created an impressive overall show. Plants had a good growth habit with strong branching and no disease.

Penstemon Dakota Burgundy, photo courtesy of CSU
  1. Penstemon ‘DAKOTA™ Burgundy’ (Penstemon digitalis) from Terra Nova Nurseries

Dark burgundy foliage was a key reason for the superior rating. Multiple shades of burgundy added interest to the dark foliage and help make the white/lavender flower color really stand out. Blooms are very prolific with a long flowering period. It was noted that although the flowers are very impressive, the plant looks very showy even when not in flower due to the attractive dark foliage that remained clean all season and never had got “floppy ear”. Plants were very reliable and had 100% survival over three seasons.

Phlox Ka Pow Pink, photo courtesy of CSU
  1. Phlox ‘Ka-Pow®’ series (Phlox paniculata) from Darwin Perennials

Evaluators were impressed with the entire series as all had similar height, were very uniform, and resistant to powdery mildew. Flowers had a long period of bloom with no color fade. The Series had a range of colors that went from soft lavender to a vibrant pink. The pink entry was noted to have some shades of coral which is unique to Phlox.

Salvia Blue By You, Photo Courtesy of CSU
  1. Salvia ‘Blue by You’ (Salvia nemerosa) from Darwin Perennials

Vibrant blue flowers were very showy with prolific amounts of blooms early in the season and an impressive repeat later in the season after a hard cut back of old blooms. The unique blue color is a great addition to the pallet of Salvia colors in the trade and evaluators said they “had to go see it” from across the garden.


To learn more about the work behind these results, find the full story at

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