The 2023 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 spans nearly three acres on the east side of the Fort Collins campus and 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 most likely to succeed.

Gardening Season 2023

“The Annual Flower Trial Garden is a vital training ground for CSU horticulture students and is part of a network of trial gardens at land-grant universities nationwide,” said Jim Klett, coordinator, and Emeritus 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 2022 evaluation are now available at area nurseries and garden centers for the 2023 home gardening season. For more detailed descriptions and photographs, visit the Flower Trial Garden website.

About the Trial Garden

CSU’s Flower Trial Garden, which draws thousands of visitors annually, relies on student gardeners, volunteers and industry supporters, and experts who help provide detailed plant performance analysis. Colorado State Extension Master Gardeners play an essential role in the 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 trial entries. The garden also receives donations from industry associations, foundations, nurseries, plant producers, and other companies in the green industry.

“Best of” Annual Flower Winners from the 2022 CSU Trials 

Best of Show – SunPatiens® Vigorous Peach Candy from Sakata® Seed America

Best New Variety – Salvia Rockin’® Deep Purple 2023 from Proven Winners®

Best Novelty – Senecio Angel Wings (‘Senaw’)^PP28,830 from Concept Plants

“Best Of” by Class

Angelonia, container – Archangel™ Blue Bicolor (‘Balarclubi’) from Ball FloraPlant®

Angelonia, ground – Archangel™ Purple Improved from Ball FloraPlant®

Begonia (Rex) – Jurassic Jr.™ Fire Spike from Ball Ingenuity®

Begonia (seed), container – Hula™ Red Spreading Begonia (PAS1438024) from PanAmerican Seed

Begonia (seed), ground – Bionic™ Green Leaf Rose from Syngenta® Flowers

Begonia (vegetative) – BK Collection Vermillion Red from Beekenkamp Plants

Calibrachoa – Bumble Bee™ Hot Pink from Ball FloraPlant®

Celosia – Flamma Bright Red from Sakata® Seed America

Coleus – Main Steet Yonge Street from Dummen Orange®

Combo – MixMasters™ Amped Up from Ball FloraPlant®

Dahlia – City Lights™ Purple from Selecta One®

Geranium, container – Sunrise™ Brilliant Red 23 from Selecta One®

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

Geranium (zonal) ground – Dynamo™ Dark Red from Ball FloraPlant®

Gerbera – Garvinea Sweet Sparkle from HilverdaFlorist

Impatiens, container – Beacon® Portland Mix from PanAmerican Seed®

Impatiens, ground – Imara XDR Rose from Syngenta Flowers

Impatiens, New Guinea – Super Sonic® White from Syngenta® Flowers

Lantana, container – Bandolista™ Pineapple from Syngenta® Flowers

Lantana, ground – Bandolista™ Mango from Syngenta® Flowers

Marigold – Endurance™ Yellow from Syngenta® Flowers

Osteospermum – Gelato Prune from Westhoff

Petunia, container – SureShot™ White from Ball FloraPlant® 

Petunia (mini) ground – Supertunia Mini Vista® Yellow from Proven Winners®

Petunia (seed), ground – FotoFinish™ Pink from Syngenta® Flowers

Petunia (vegetative), ground – DuraBloom® Electric Lilac from Dummen Orange®

Portulaca – Pazaaz™ Yellow Improved from Danziger

Rudbeckia – Sunbeckia Maya from Bull Plant Genetics

Salvia – Rockin’® Deep Purple 2023 from Proven Winners®

Sun Impatiens – SunPatiens® Vigorous Peach Candy from Sakata® Seed America

Verbena, ground – EnduraScape™ Pink Bicolor (Balendpibi’)^PP28,455 from Ball FloraPlant

Verbena, container – Vanessa™ Compact Neon Pink from Danziger

Vinca – Cora® XDR Punch from Syngenta Flowers®

Zinnia – Magellan™ Orange from Syngenta Flowers®

Other Outstanding Plants

Dahlia Labella® Maggiore Fun Chocolate Yellow from Beekenkamp Plants

Lantana Bandolista™ Red Chili from Syngenta Flowers®

Gerbera Garvinea Majestic Light Pink from HilverdaFlorist

Sun Impatiens – SunPatiens® Compact Classic White (‘SAKIMP068’) from Sakata® Seed America

Zinnia Zesty™ Purple from PanAmerican Seed®

Evaluation

The trial evaluation was held on August 9, 2022. 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 (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 5 (1 = very poor performance; 5 = excellent performance). These numerical evaluations were used to calculate the average ratings for each trial variety. Participants used their tablets or cell phones to evaluate the plants electronically. 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 August 9 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 with ten or more trial entries. The “Best Of” award was given to classes whose top-five list had ratings of at least 3.0, and one could be considered superior. A sub-committee of university and industry representatives revisited the garden on September 8 to review the top-five list and verify the superiority of the top-rated varieties later in the season. A majority vote was taken for each class to determine the final selections for winners.