Annual Flower Trial Garden reveals this year’s winners

The 2019 gardening season is almost upon us. If you want to know what flowers to plant this growing season, a list of great possibilities comes from Colorado State University’s Annual Flower Trial Garden.  The 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.

Best of” Annual Flower Winners from the 2018 CSU Trials

Best of Show – Salvia ‘Big Blue’ from PanAmerican Seed

A later bloomer that is worth the wait was impressive with large flower spikes that are showy in the garden as well as making a good cut flower. Plants had dark green foliage, strong upright growth habit, excellent branching and very uniform overall. A strong favorite with bees as well as humans.

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Best Novelty – Artemisia ‘MAKANA™ Silver’ from Terra Nova® Nurseries, Inc.

This fine textured foliage plant makes a great complement to many other plants in a classic border. The beautiful silver foliage is dense on vigorous and very compact and uniform plants. It would look great in both a container as well as ground. It makes a good filler plant as well adding a strong textural element to any garden.

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Best New Variety – Rudbeckia ‘Rising Sun® AS Chestnut Gold’ from Green Fuse™ Botanicals

Huge flowers covered this plant all season creating impressive flower power.  Besides the prolific flowering, the intense coloring of the flowers make this a definite “55 MPH plant.” It is impossible not to be impressed even from a brief glance at a great distance.

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“Best Of…”  by Class

Argyranthemum – Limero White from Benary+

Large, crisp white, flowers covered the canopy that were very eye-catching.  Plants were self-cleaning and were popular in regard to having low maintenance but high visual impact. The blooms were long lasting while the plants also had great uniformity.

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Angelonia – Archangel™ Raspberry from Ball FloraPlant

Flowers were abundant all season but stood out also for the intense unique raspberry color. The upright plants maintained excellent uniformity and made a nice complement to the flowers above the glossy green foliage below.

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Begonia semperflorens (Shade) – ‘Megawatt™ Pink Bronze Leaf’ from PanAmerican Seed

The vigorous plants were characterized by their large leaves, strong stems and large flowers. The bright pink flowers were very floriferous and had excellent contrast with the dark foliage. Blooms were self-cleaning so the plants always looked fresh.

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Begonia hybrids – ‘I´Conia Portofino Orange’ from Dümmen Orange

Vibrant orange flowers appeared even brighter against the very dark bronze foliage. The serrated edges and sheen to the leaves created an attractive leaf shape. Flowers were large and made a dramatic statement in a container.

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Begonia elatior – ‘BK Collection Evi Bright Pink’ from Beekenkamp

Large pink flowers with double petals had good tolerance to sun and heat all season and still looked fresh into September. Flowers were abundant and very showy.  Plants were very uniform and would look good in either a landscape or container setting.

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Bracteantha – ‘Mohave™ White 19’ from Selecta

Clean white flowers covered the canopy and made a dazzling display in full sun.  Plants were very uniform with a nice mounding growth habit. The prolific flowers were also everlasting and excellent for dried bouquets.

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Bidens – ‘Bidy Boom Red’ from Dümmen Orange

Large amounts of long lasting red flowers were packed on a smaller, compact plant with a very tidy growth habit. Blooms also had very intense color to create a lot of flower power for a small plant. Bees love this flower.

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Calibrachoa – ‘Calitastic® Papaya’ from Westhoff

Unique color and a larger bloom made this standout from other calibrachoas.  The bicolor flowers had a nice bright color and strong blooming. Growth habit was very uniform and looked good overall.

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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 are vigorous and have good garden performance.

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Coleus – ‘FlameThrower™ Serrano’ from Ball FloraPlant

The attractive dark red foliage had a bright green edge that created a lot of contrast and a bold look.  Leaf shape was also unique and added interest.  Plants did not flower and kept a very uniform appearance all season.

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Combination – ‘Kwik Kombos™ Fire and Ice™ Mix’ from Syngenta

Plants created a ball of flowers in a container that had a very high “Wow!” factor.  Colors were vibrant and made an excellent mix.  It was noted that very few combos work with different genera but this is the exception as the bidens, petunia and lobelia were equally represented and none dominated the other.

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Dahlia – ‘Temptation Orange’ from Dümmen Orange

The intense dark foliage makes the color of the clear orange flowers really pop out.  The contrast was especially good in full sun and flower color doesn’t fade.  Dark foliage also hides dead heads and requires less maintenance.  Growth habit was very uniform.

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

Impressive vigor and flowering were the obvious characteristics of this winning plant.  Prolific flowering and vibrant color made for exceptional flower power.  This is definitely a great choice for a landscape plant.

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Geranium (Zonal) – ‘Brocade Cherry Night’ from Dümmen Orange

Plants were unique with foliage that has a very large zonation with a rich chocolate color.  The dark foliage makes for high contrast with the bright rose colored flowers.  The tight double flowers have a bit of a multiflora look to them.  Overall the plants were very uniform.

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Ipomoea – ‘SolarPower™ Black Heart’ from Ball FloraPlant

Extra-large, heart shaped leaves were dark and created a bold appearance.  Plants had good vigor but maintained a compact and uniform growth habit that “plays well with the neighbors”.

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Lantana – ‘Lucky™ Sunrise Rose’ from Ball FloraPlant

This is a dependable performer and is a winner from multiple years in the past as well as 2018.  The bright flowers had a mesmerizing mix of colors often found in a sunrise.  Plants were very uniform and flowering was very abundant all through the season.

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Lobularia – ‘Passionaria™ Purple White’ from Ball Ingenuity

Flowering was so prolific that no foliage was visible.  Plants created a mass of intense purple and white bicolor flowers that looked great all by themselves or would look good combined with others.  The growth habit was very compact and uniform

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Marigold (French) – ‘Super Hero Dark Orange’ from Benary

Dark green foliage combined well to show off the intense orange flowers.  Plants had a nice mounding growth habit that looked good without any deadheading through early September.  The cheerful looking flowers would look great in any border.

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New Guinea Impatiens – ‘Sun Harmony™ Blushing Orchid’ from Danzinger

Plants were both vigorous and very floriferous and made a very colorful container.  The large flowers held up to the sun and had added interest due to the light lavender striping in the petals.  Growth habit was very uniform.

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Osteospermum ‘Osticade™ Lemon’ from Danziger

Abundant clear yellow flowers were unusually large and had a deep yellow eye for added interest.  Blooms were consistent all season long and very showy with uniform plants with clean foliage.

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Pentas – ‘Lucky Star® Dark Red’ from PanAmerican Seed

Rich red flowers made a great contrast with the dark green foliage.  Flowers were abundant and very showy.  Plants were vigorous with a tight and compact growth habit.

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Petunia (Container) – ‘Constellation® Aries’ from Westhoff

Flowers had a unique appearance with speckles and blotches on blooms but were also very floriferous.  The densely flowered plants were noted for a good uniform growth habit that held its shape late into the season.

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Petunia (Seed) – ‘Easy Wave® Silver’ from PanAmerican Seed

Abundant flowers covered this plant and had superior performance in the ground.  Flowers were mostly white with a silky sheen and a hint of lavender primarily near the eye.  The overall growth habit was very uniform.

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Petunia (Spreading) – ‘Supertunia Vista® Bubblegum’ from Proven Winners

This is a multi-year winner from many past trials and is considered to be possibly the best petunia in the last 10 years.  It always has a dependable show of prolific pink flowers with exceptional vigor.

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Portulaca – ‘ColorBlast™ Double Magenta’ from Westhoff

Plants were vigorous and very uniform.  Double flowers were very showy and had the added benefit of staying open longer than the single petaled varieties.  Plants stood out for the unique magenta flower color and spreading growth habit.

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Salvia – ‘Mystic Spires Improved’ from Ball FloraPlant

Another past winner, it stood out again in 2018 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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Scaevola – ‘Scalora® Pearl’ from Westhoff

Plants were vigorous and covered with abundant white flowers.  The dense round growth habit was very uniform and superior to many other varieties.   The multiflora blooms were a favorite with many pollinators in the garden.

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Verbena – ‘Lanai® Upright Twister Watercolor’ from Syngenta

Abundant flowering covered the canopy almost all season with attractive shades of soft lavender that was attractive even as the blooms faded.  Plants had a long lasting flower display and seemed to “bury its dead” blooms under new ones.  Uniform growth habit and lack of any sign of mildew also made this plant a winner.

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Vinca – ‘Tattoo™ Papaya’ from PanAmerican Seed

Very unique flower color and abundant blooms were very impressive.  Flowers had a very unusual and beautiful “inky” blush pattern that helped earn the first part of the name, “Tattoo”.  Plants had an upright growth habit and can grow well in full sun or part shade.

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Other Outstanding Plants

Anigozanthos ‘Kanga Jump Red’ from Green Fuse Botanicals

Another novelty plant that is popular in Australia but just starting to make an impression in the United States.  Foliage almost looks succulent or tropical while the flowers almost look like red fuzzy pods for a very unique overall appearance.  Blooms were very abundant and emerged bright red and matured to a dark maroon color over a long period of time.

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Begonia ‘Tophat™ Pink’ from Syngenta

Plants had great vigor that just kept getting bigger and better as the season progressed until a hard frost.  Produces abundant, large pink blooms that are outstanding.  Plants had a very uniform growth habit.

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Coreopsis ‘Electric Sunshine’ from Darwin Perennials

This was a non-stop bloomer which still looked great late in the season.  Bright yellow flowers also had a splash of dark red on the petal for excellent contrast.  Plants were vigorous but considered an annual for Zone 5.

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Gomphrena ‘Truffula™ Pink’ from Proven Winners

Abundant and long lasting pink flowers covered this plant all season.  Well branched, mounding plants were very uniform and considered “well behaved” even with the vigorous growth.  This low maintenance plant does not require deadheading and can tolerate some dry conditions.

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Iberis ‘Summer Snowdrift’ from Darwin Perennials

Bright white flowers covered the plant all summer without any shattering.  Plants had a very compact and mounded growth habit that were covered with white blooms.  Flowers give a similar flower effect as the perennial type.  They bloom all summer but unfortunately are only considered an annual for Zone 5.

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Plant Evaluation

The trial evaluation day was held on August 6, 2018.  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.

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. 9 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 2018 “Best Of” Annual Flower winners and the complete list and report can be found at

Largest Garden of its kind West of the Mississippi

Colorado State University Annual Flower Trial Garden

“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.”

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.

Winners from the 2018 evaluation are now available at area nurseries and garden centers for the 2019 home gardening season.