2019 Annual Flower Trial Garden’s list of winning flowers

The COVID-19 pandemic hasn’t stopped Colorado State University’s Flower Trial Garden from planting and blooming on schedule this year. For many spending more time at home lately, the approach of backyard gardening season will surely prove a welcome and natural stress reliever. If you want to know what annual flowers should thrive this growing season, Colorado State University researchers recently revealed their top annual picks.

The Trial Garden, which spans nearly three acres on the east side of the Fort Collins campus, is a Northern Colorado showpiece with a focused research and outreach purpose. Each year, the Annual Flower Trial Garden tests and analyzes the performance of more than 1,000 varieties of annual bedding plants in Colorado’s harsh growing conditions. Dozens of expert evaluators rate the plants for vigor, growth pattern, bloom and other characteristics. The trial results help home gardeners identify annual bedding plants that are most likely to succeed.

Gardening Season 2020

“The Annual Flower Trial Garden – also a vital training ground for CSU horticulture students – is a part of a network of trial gardens at land-grant universities nationwide,” said Jim Klett, faculty coordinator and professor in CSU’s Department of Horticulture and Landscape Architecture. “It’s the largest garden of its kind west of the Mississippi River.”  Winners from the 2019 evaluation are now available at area nurseries and garden centers for the 2020 home gardening season. For more detailed descriptions and photographs, visit www.flowertrials.colostate.edu.

About the Trial Garden

CSU’s Flower Trial Garden, which draws thousands of visitors each year, relies on student gardeners, volunteers and industry supporters and experts who help provide detailed analysis of plant performance. Colorado State Extension Master Gardeners play an essential role in planting and maintenance of the garden. The outcome of this research is valuable to the industry and home gardeners alike. That’s because the Rocky Mountain region has unique growing conditions, characterized by high altitude, intense solar radiation, drying winds, severe hailstorms, large fluctuations between day and night temperatures and a season-long need for irrigation.

The Trial Garden receives no direct state or public funding. It is funded primarily by fees from plant-breeding companies that submit entries to the trials. The garden also receives donations from industry associations, foundations, nurseries, plant producers and other companies in the green industry.


The trial evaluation day was held on August 6, 2019. Approximately 150 judges consisting of industry representatives, master gardeners, university employees and trial garden advisory committee members evaluated the plant varieties for performance using a combination of these criteria:

Plant Quality:

Uniformity of plant habit

Bushy, well-branched shape versus open and leggy

Healthy foliage (deep green versus chlorotic, yellow leaves)

Foliage texture

Disease resistance

Flower Quality:

Flower power (number of flowers per plant, substance and holding power)

Flower presentation (i.e. not hidden by the foliage)

Color uniformity

Stable color (resistance to fading) and stable pattern (for bicolor)

Flower size and uniformity of flowers

Balance of color in a mixture

Overall Presentation:

Overall “clean” look, versus visible spent blooms

Fragrant flowers and/or foliage

Good vigorous growth

Resistance to climatic stress

Novelty value of unique features

Overall consumer appeal

Plant varieties were rated on a scale of 1 to 10 (1 = very poor performance; 10 = excellent performance). These numerical evaluations were used to calculate the average ratings for each variety in the trials. Participants were to use their tablets or cell phones to electronically evaluate the plants. The pre-generated comments they could choose from included: Low vigor, Vigorous plant, Few flowers, Many flowers, Uniform, Non-uniform, Unique color and Some chlorosis.

Selection of “Best Of” Winners and “Other Outstanding Plants”

Ratings from all evaluators on Aug. 6 were averaged and the top five in each class were placed on a preliminary list. A class is determined to be any group of plants in the same genus that consisted of 10 or more trial entries. The “Best Of” award was given to classes whose top-five list had ratings of at least 6.0 and one of them could be considered superior.  A sub-committee of university and industry representatives revisited the garden on Sept. 12 to review the top-five list and verify the superiority of the top rated varieties later in the season and not just on Aug. 6. A majority vote was taken for each class to determine the final selections for winners. “Other Outstanding Plants” was an award created to recognize other plants that deserved special recognition; especially for those plants that did not have ten varieties to make up a judging class. The following is a list of the 2019 “Best Of” Annual Flower winners and the complete list and report can be found at www.flowertrials.colostate.edu.

Best of” Annual Flower Winners from the 2019 CSU Trials

 Best of Show – Dahlia ‘City Lights™ Purple’ from Selecta

The dark foliage and flowers of this variety made a dramatic statement in the garden. The growth habit had excellent uniformity with upright plants that did not flop despite overhead irrigation. Plants had strong flower power and were favorites of the bees.

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Best Novelty – Begonia T-REX™ Ruby Slippers from Terranova

The huge red leaves had silvery edges that would make a great contrast for color and texture with other plants in the garden. Plant is grown mainly for the foliage. It made a very eye-catching plant for areas with dry shade and can be used in either the ground or in containers.

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Best New Variety – Petunia ‘Headliner™ Dark Saturn from Selecta

The unique flower color was very impressive with a bold soft creamy yellow and a dark star shaped eye. Plants had strong vigor and developed into a uniform blanket of blooms in the container.  Plants and flowers held up well in the heat.

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“Best Of…”  by Class

Angelonia – ‘Carita™ Purple’ from Syngenta Flowers

All plants had superior overall appearance due to a very uniform growth habit and abundant blooms. The deep purple flowers were very prolific and were quite showy even through the hottest part of the summer.

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Bacopa – ‘Betty® White’ from Green Fuse Botanicals

Plants had exceptional vigor and dark green foliage that cascaded over the side of the container. White flowers were abundant and made a nice contrast with the dark foliage. The trailing habit works great in containers.  Flowering continued the entire season.

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Begonia (shade) – ‘BK Collection Vermillion Red’ from Beekenkamp

The overall appearance was striking all through the season with a very intense, rich shade of red and abundant blooms.  In addition to the prolific flowering, blooms were double which greatly added to the overall show. Plants had dark green foliage and were very uniform.

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Begonia (sun) – ‘Tophat™ Pink’ from Syngenta Flowers

Plants had great vigor but maintained a very uniform growth habit. Flowers were unusually large and very abundant which made them immensely popular with the bees. Plants looked great in either the ground or container and only got better looking even into the fall.

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Begonia (tuberous) – ‘Illumination® Apricot Shades’ from Benary+

Large, double, bicolor blooms in soothing shades of apricot were very attractive. The trailing growth habit works well in containers. Plants had good vigor and very healthy.

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Bidens – ‘Campfire™ Flame’ from Proven Winners

Flowers had beautiful shades of orange/red/yellow and fade to a nice rustic color. Blooms were prolific and kept a solid canopy of color all through the summer and into September.  Growth habit was very uniform and the overall effect was quite striking in a container.

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Calibrachoa – ‘Superbells® Dreamsicle Improved’ from Proven Winners

Flowers had a very good orange color that provided a nice bright appearance. Foliage complements the flower color and had a hint of a silver sheen to it. Plants were vigorous but not open which makes for an attractive growth habit.

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Celosia – ‘Kelos Fire Scarlet’ from Beekenkamp

The attractive dark foliage was impressive all by itself but the abundant petite flowers were bright and made a great contrast with the foliage. Plants were vigorous and had good garden performance. Dependable performance made this a repeat winner in 2019.

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Coleus – ‘MAIN STREET Beale Street’ from Dummen Orange

The rich burgundy leaf color provided color to the garden all season long. Plant vigor was excellent while also maintaining a very uniform growth habit. Flowers were virtually non-existent. Plants looked great in both the ground and containers.

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Combination – ‘Mixmasters™ Blooms of Allegiance’ from Ball FloraPlant

Combinations which are perfectly balanced, allows for greater genetic diversity in mixes. The prolific flowering from blue scaevola which contrasted nicely with the red/orange lantana and a few white angelonia. This mix had excellent vigor and a lot of flower power with the bright colors. It looked great in containers and had a nice growth habit.

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Geranium (interspecific) – ‘Caliente® Coral Salmon’ from Syngenta Flowers

This is a winner from previous years as well as in 2019 due to impressive vigor and dependable flowering. Prolific flowering and vibrant color made for exceptional flower power. Flowers also had attractive dark stems which made a nice contrast with the bright flowers. This definitely is a great choice for landscapes.

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Geranium (ivy) – ‘Gerainbow Red’ from Benary+

Deep red blooms were very showy and prolific. Noted for being a European style of flower with large blooms and excellent trailing growth habit. A great choice for containers due to superior heat tolerance and resistant to edema.

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Geranium (zonal) – ‘Galaxy™ Watermelon’ from Ball Floraplant

The large watermelon colored flowers looked good enough to eat. The bright, bi-color flowers were very attractive with just a small splash of white for the eye. Plants had good uniformity and were covered in blooms.

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Gerbera – ‘Sweet Sunset’ from Florist Holland NA

Abundant flowers and attractive orange/red color created a lot of flower power that lasted late into the season. Plants were uniform with lush green foliage.

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Impatiens – ‘Beacon™ White’ from PanAmerican Seed

Snowy white flowers covered the plant canopy providing a bright splash of color for shady areas. The vigorous plants maintained a controlled growth for excellent uniformity. The added bonus for the entire ‘Beacon™’ series is that they have strong resistance to Impatiens downy mildew which has devastated many Imapatiens walleriana in the past few years.

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Lantana – ‘HAVANA Sunrise’ from Dummen Orange

This heat loving plant had good branching, large umbels of flowers over dark green foliage. The compact growth habit with prolific very attractive multi-colored flowers with shades of pink, cream and yellow makes it outstanding. It has a very uniform growth habit and looked great in a container.

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Lobelia – ‘Hot® Giant Blue’ from Westhoff

Striking shade of blue flowers and prolific blooming through the summer and late into the season set this entry apart from the rest. Plants had good vigor and growth habit.

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New Guinea Impatiens – ‘SunPatiens® Vigorous Red Improved’ from Sakata

Large red flowers covered the foliage creating a nearly solid canopy of color that provided dependable blooming all season long. The foliage that was visible was a nice dark green that helped make the flower color “pop.” Plants had great vigor with and upright mounding growth habit that was very uniform.

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Osteospermum – ‘Tradewinds® Lemon Zest’ from Syngenta Flowers

Yellow daisy-like flowers were bright, bold and abundant. This mid-summer bloomer amazed anybody waking by. Plants had a good symmetrical growth habit along with good vigor.     

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Pentas – ‘Lucky Star® Lavender’ from PanAmerican Seed

The long lasting, soft lavender flowers were prolific and very showy. Vigor was excellent but plants maintained a very tight, compact growth habit. Blooms were also a magnet for butterflies.

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Petunia (container) – ‘Crazytunia® Tiki Torch’ from Westhoff

Flower color was exceptional with a bold and colorful combination of red, yellow and orange. Combined with strong plant vigor and abundant flowering, this entry was clearly a standout.

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Petunia (ground) – ‘ColorRush™ White from Ball FloraPlant

The uniform mound of bright, white flowers was impressive all season long. Plants were vigorous but maintained a tight growth habit.

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Petunia (seed) – ‘Easy Wave® Purple from PanAmerican Seed

Carpet of purple flowers created a spectacular display of color throughout the summer and into September. Blooms were large and a vibrant shade of purple. Plants developed into a uniform mat of flowers.

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Portulaca – ‘ColorBlast Double Yellow’ from Westhoff

Double yellow flowers simulate small explosions of color and had the added benefit that the blooms stay open longer than single petal varieties. This heat loving plant was vigorous and looked great in containers.

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Salvia – ‘Mystic Spires’ from Ball FloraPlant

Another dependable performer and past winner, it stood out again in 2019 for the abundant dark purple flowers and vigorous, upright plants. Foliage was clean and glossy. This was another bee friendly plant that was often buzzing with excitement.

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Thunbergia – ‘TowerPower™ White’ from Westhoff

As the name implies, plants had impressive vigor and easily climbed the trellis in the container and spilled over onto the ground creating a tower of flowers. White blooms were attractive with a dark eye. The entire ‘TowerPower™’ series had very similar vigor and growth.

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Verbena – ‘Lascar™ Black Velvet’ from Selecta

The unique black flower color and prolific blooming made this a standout from the rest. The deep black color would mix well with other colors. Plants had good vigor and uniform growth.

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Vinca – ‘Soiree Kawaii Coral’ from Suntory

Tiny coral colored flowers were bright and prolific making an impressive display of color in either ground or containers.  Additional features were the small white eye on the bloom and glossy green foliage. Plants stayed compact all summer long with no leggy branches.

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Zinnia – ‘Zesty™ Scarlet’ from Ball Ingenuity

Vibrant scarlet flowers had great flower power with the abundant flowering and uniform growth habit. Plants had excellent vigor and were disease free all-season long.

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Other Outstanding Plants

Digitalis ‘Pink Panther’ from American Takii     

This plant flowers the first year on compact plants with small foliage. The heavy branching produced multiple spikes at one time and did not require pinching. The sterile blooms are long lasting and attracts pollinators.   Pink flowers are abundant and very attractive.

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Geranium ‘Clarion® Peach’ from Benary+

This regal type of geranium had large blooms with truly mesmerizing shades of peach, pink and white. The uniform, mounding plants were covered by blooms all season long and were a definite show stopper. Other entries in the same Clarion® series were also impressive with excellent vigor and flowering.

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