“Top Performer” Perennials” from the 2021 Colorado State University Flower Trials

Posted by: Dr. Jim Klett, Department of Horticulture and Landscape Architecture, Colorado State University

 In 2021, Colorado State University continued its three year herbaceous perennial trial and chose eight perennials as the “Top Performers” from 126 that were planted in 2019. To become a CSU ‘Top Performer’ it has to have great survival percentages after two winters and three growing seasons and scored excellent throughout the three growing seasons. A sub-committee if the CSU Annual Trial Garden Advisory Committee evaluated twelve of the top performing perennials in November of 2021 by examining photos of these plants taken every two weeks during the three year growing seasons. A majority favorable vote from the committee is needed for a perennial to become a CSU ‘Top Performer’.

 Therefore perennials that get this description have proven to be adaptable for the Front Range of Colorado. The following eight plants have been awarded this category for 2021 after three years of extensive trialing.

 A complete report on the perennials in the trial can be viewed at www.flowertrials.colostate.edu under the Perennial Trials menu tab.

Achillea ‘Firefly Sunshine’

(Achillea x hybrida) from Walters Gardens, Inc. /Proven Winners®

Vibrant yellow flowers provided a lot of color and with a long-lasting bloom. Dark green foliage also made the flower color stand out. It had superior qualities with a more compact growth habit that did not lodge despite overhead watering and had excellent winter survival. It was also noted that it did not spread around the garden which is a definite plus.

 

Brunnera ALCHEMY™ Silver

(Brunnera macrophylla) from Terra Nova Nurseries

This great plant can brighten up a shady area with a constant display of beautiful silver foliage. Plants are vigorous and are covered by a delicate cloud of light blue flowers from about May into June. Leaves are relatively thick and stands up well with strong stems to create a very attractive and uniform growth habit. 

Eupatorium Euphoria™ Ruby

(Eupatorium purpureum 'FLOREUPRE1’^PP31,668) from Darwin Perennials®

Shorter and more compact than the species, this is a nice medium size plant for the modern landscape. This was a unanimous choice for the “Top Performer” award with dependable light ruby/lilac-colored flowers that combines well with dark leaves and stems. It was noted to be an excellent pollinator plant.

 

Perovskia CrazyBlue

(Perovskia atriplicifolia 'CrazyBlue' ^{PP #25,639}) from Darwin Perennials®

Plants were noted to have superior flowering and growth habit. The flowers have a long lasting bloom period and the violet-blue flowers last longer than other Perovskia. Uniform plants had interlacing branching and sturdy stems that kept it from lodging and maintained an attractive appearance all season. It is a mid-sized plant about 3-4 feet in height.

 

Rosa Sunbeam Veranda®

(Rosa x ‘ Korfloci52’ ^PP23,314) from Star® Roses and Plants

Glossy, dark green foliage made the bright yellow flower color even more stunning. Blooming started in June and lasted well into September. The compact size makes this a great choice for smaller gardens spaces. Plants had excellent winter hardiness.

 

Rosa Cherry Frost™

(Rosa x ‘Overedclimb’^PP31,286) from Star® Roses and Plants

 Abundant bright red flowers and good disease resistance make this a good climbing rose for Colorado. Clusters of small flowers kept repeating throughout the growing season in flushes for long lasting color. It had excellent winter survival.

Sedum Prima Angelina

(Sedum rupestre) from Darwin Perennials®

Great neon yellow foliage makes this an excellent foliage plant in the summer and it also is quite showy in the winter with a nice shade of red. The spreading growth habit is very uniform and a great choice with rock gardens or combined with other Sedums for additional color contrast. Prima Angelina is superior to the straight Angelina with better branching and growth habit while also being less brittle.

Veronica Moody Blues® Mauve Improved

(Veronica spicata) from Darwin Perennials®

Impressive vibrant, mauve colored blooms covered the plants at peak and repeated later in the season. Well branched plants were compact and very uniform with 100% winter survival. It has the added bonus of being a good bloomer the first year in the garden.

 

"Top Performer" Perennials from the 2020 CSU Perennial Trial

Posted by Jim Klett, Professor, Colorado State University, Department of Horticulture and Landscape Architecture

Evaluating perennials in the Rocky Mountains

The purpose of the Perennial trial garden is to evaluate 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 Colorado State University 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.

Performance Evaluation

Photos and data on plants and flowers were collected on a bi-weekly basis from May to early October. Dead plants in the trial were not considered in the bi-weekly evaluation; thus, the ratings given only reflect the live plants. Members from the Perennial Trial subcommittee also evaluated and wrote comments for each plant variety in June, July, August and September. Plants and flowers were rated 0-5 using the following scale:

 0 = Dead/No flowers

1 = Poor: Plants are very sick or dying, extremely few flowers

2 = Below Average: Plants are unattractive in some form, i.e. – leggy growth habit, chlorotic or low vigor, flowers are few and occurring sporadically

3 = Average: Plant appearance with growth characteristics that would be expected for the time of season; flowers would be few but uniform across the plants

4 = Good: Plants look attractive (foliage, growth habit, etc.,); flowers are blooming strong and showy

5 = Excellent: Plants are very healthy and uniform; flowering is impressive

 

Selection of “Top Performers”

On November 20, 2020, a conference call was convened with CSU staff and the Perennial Trial Garden Subcommittee. Pictures of entries from the 2018 planting were posted to the Perennial Trial website for review. Data from the growing season was compiled and emailed to each evaluator prior to the conference call for review. After discussion and looking at the pictures taken throughout the season, each plant was voted on by each member of the committee as to whether it should be awarded the designation as a “Top Performer”.

2020 “Top Performers” from CSU Perennial Trials

 

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 foliage for maximum show but had good structure and did not lodge. Plant were uniform and very attractive with glossy green, flat leaf blades.

 

2.       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 a long time and created an impressive overall show. Plants had a good growth habit with strong branching and no disease.

 

3.     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.

 

4.     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. 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.

 

5.     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.

2019 "Top Performer" Perennials Announced from CSU Flower Trials

Posted by Jim Klett, Professor, CSU Department of Horticulture and Landscape Architecture

Our three year (2 winter) herbaceous perennial trials at Colorado State University continues to grow each year with 115 new entries for a total for 270 entries. Plants are evaluated for plant vigor, uniformity, floriferousness and tolerance to environmental and biotic stresses. The following six perennials have been awarded the 2019 “Top Performer” perennial designation after performing superiorly for three growing seasons and two winters in our Fort Collins, Colorado trials.

A complete report on the perennials in the trial can be viewed at www.flowertrials.colostate.edu under Perennial Trials menu.

Millenium Ornamental Onion from Eason Horticulture Resources and Stonehouse Nursery

(Allium hybrid 'ALLMIG1')

This was a definite “show stopper” plant that was described as having an “insane” amount of blooms.  Flowers were a nice shade of pink and were a favorite of many bees and butterflies.  The flowers combined well with a nice compact plant with clean foliage and very uniform growth habit.  Blooming lasted a long time and flowers did not lodge even with overhead irrigation.  It has been reported to grow well even at 8,000’ in the mountains.  Removal of spent blooms can result in some repeat blooming or can be left for winter interest.  Judges were in unanimous agreement to designate it as a winner. 

Kahorie^® Scarlet Border Pinks from Dummen Orange

(Dianthus x hybrida Kahorie^® 'Scarlet')

Very showy in the spring with a very vibrant color and attractive plants.  Flower color was not a true scarlet but a beautiful shade of hot rose or cherry.  Plants had superior winter hardiness that was consistent over three years and did not die out in the center as did many other Dianthus.  Plants were attractive even when not in bloom with a nice tidy, compact growth habit.

SUMMERIFIC^® Cherry Choco Latte Rose Mallow from Walters Gardens, Inc.

(Hibiscus x hybrida 'Cherry Choco Latte'^PPAF)

Large, two tone blooms were captivating with a striking combination of pink and white.  It makes a great choice for providing color late in the season.  Plants were relatively low maintenance as the old blooms were self-cleaning.  Foliage had shades of dark red that was maintained throughout the season.   Plants also had a nice growth habit that did not lodge and the mid-size height made a good balance with the flower size.

Lami™ Dark Purple Spotted Deadnettle from Danziger

(Lamium maculatum 'Dark Purple')

Dark purple flowers combined with dark green foliage and a very uniform growth habit to make a very impressive groundcover.  This versatile plant did not burn in the sun and did well in the shade.   It has also been reported to look great even at 8,000 feet elevation.  Plants have superior vigor and provide a long period of bloom. 

Bandwidth Maiden Grass from Darwin Perennials

(Miscanthus sinensis 'NCMS2B'^PP29460)

This is a good selection for today’s smaller gardens and landscapes as the plant maintains a nice uniform growth habit that is only 3-4’ in height.  Plants did not bloom but foliage is very attractive with yellow stripes running across the blade.  The variegated foliage did not revert and was impressive all three seasons.  Flowers are not needed for interest as the yellow and green contrast in the leaves is very showy.

GRANITA^® Orange Ice Plant from Plant Select^®

(Delosperma ‘PJS02S’)

Bright, iridescent orange flowers blanket the plant creating an impressive show of flower power.  Large flowers bloom over a long period.  Plants make a very attractive ground cover as the beautiful green foliage forms a nice dense mat that tightly hugs the ground.  Vigor is excellent and makes a good spreader.  Cold hardy and well suited for this area.