By Jim Klett, Colorado State University Colorado State University Cooperative Extension Specialist, Landscape Plants
The judges have spoken at Colorado State University, and a verbena, 'Aztec plum,' has been named Best of Show for 2000 in the university's Annual Flower trials.
Annual flowering plants -- from begonias to vincas -- have been evaluated in the university's test Gardens. The results will help Gardeners select plants for growth habits most favorable to Colorado.
In addition to 'Aztec plum,' an Argyanthemum, 'Comet Pink,' was named outstanding new variety for the season.
The plants were among 945 tested last year. Twenty-eight seed companies participated and helped fund the 2000 trials. The winning verbena was developed by Ball Flora Plant and the Argyanthemum is a product of The Flower Fields.
Geraniums -- both seed and zonal -- played a major role in the 2000 trials with 'Morella' from Agrexco, Ltd. gaining recognition as the best zonal geranium. This plant proved adaptable to alkaline soils. It featured deep green leaves and vigorous growth throughout the growing season. Flowers were evenly dispersed across the plant and provided a combination of pure red flower color against the deep green leaves.
A selection from Goldsmith Seeds, 'Maverick Red,' took the honors for best seed geranium. The leaves of this vigorous grower had showy zonations on the foliage, a great accent for its clear red flowers.
In container trials, 'Picasso' from Fischer USA won as best ivy geranium. The Fischer entry exhibited a vibrant burgundy and white flower color.
All seed and zonal selections were grown in beds, while the ivys were grown in both the outdoor and indoor pot (container) trials.
Impatiens also made a big impact during the 2000 trials, with the number of impatiens increasing considerably over the past several seasons. 'Celebration Rose Star' from Ball Flora Plant won top honors as the best of the New Guinea impatiens. This variety showed nearly perfect uniform flower coverage for most of the growing season. The rose bi-color flowers provided superb balance against the plant's dark-colored foliage.
Winner of the double impatiens category was 'Fiesta Pink Ruffles' produced by Ball Flora Plant. The Fiesta series, as a group, maintained a full and vigorous growth habit. This variety was awarded top honors because of its early flower color and uniform well-balanced flower placement.
From the seed-grown impatiens, judges chose 'Dazzler Merlot Mix' as winner. Developed by Ball Seed, 'Dazzler' featured a desirable growth habit and good mixture of flower colors.
Other winning annuals
Overall, wax begonias performed very well in the 2000 trials with 'Party Red' from Benary Flower Seeds being voted best. Individual plants were fully covered with abundant red blooms throughout the summer. Each flower was highlighted by bright yellow stamens, which provided great contrast against the red petals.
'Colorburst Red' from The Flower Fields proved an excellent Calibrachoa for container plantings. This vigorous grower maintained a rounded growth habit that completely filled its pot. The plants were fully covered by a blanket of metallic red flowers throughout the season.
Highest ranked dianthus was 'Bouquet Purple.' This variety entered by Pan American Seed displayed excellent purple flower color and held its blooms high on the plants' foliage. Its upright somewhat airy growth habit gives this plant a natural appeal in the Garden.
Pan American Seed produced the best marigold in 2000. 'Sweet Cream' is an extremely uniform variety with a vigorous growth habit that makes it an instant eye catcher. It features large cream-colored flowers that fully cover the plant. In the trials, this variety also showed good resistance to aster yellows.
Highest ranked nicotiana was 'Saratoga Deep Rose' from Goldsmith Seeds. This plant featured a uniform growth habit with a good balance of flowers-to-foliage. Growth remained lush throughout the summer, and the plant displayed many deep rose-colored flowers that resisted fading.
Best osteospermum was 'Dandenong Daisy' from Euro American Propagators. This variety held good flower coverage throughout the heat of summer. Its tolerance to adverse conditions along with its large pure white flowers makes it a winner.
A number of pentas were tested with a variety from Ball Seed, 'Butterfly Deep Pink,' claiming number one spot. Its glossy dark green leaves provided an excellent backdrop for its star-like pink flowers.
Of the numerous petunias under test, the winner was a grandiflora type from Goldsmith Seeds. 'Storm Lavender' proved to be a vigorous grower and showed few signs of chlorosis in clay soil. Large lavender flowers were held high on the foliage through most of the growing season.
'Margarita Rosita,' from Waller Genetics, claimed title as best portulaca. Its clear rose double flowers bloomed in abundance and were spaced evenly across the plant's surface. Rosita maintained a full rounded growth habit.
'Red Hot Sally' from Ball Seed outperformed other Salvia splendens. This variety performed well even when grown in full sun at Colorado's elevation. Its growth habit was uniform, and it flowered consistently with dark red blooms.
The Vinca Diva series from Fischer USA proved excellent examples of vinca. 'Diva Scarlet' featured a uniform growth habit and was a vigorous member of this series. Its deep red blooms provided great color.
The annuals were transplanted to outdoor beds between May 23 and June 16. Each outdoor bed held two rows of each variety with 12 plants per row. The rows were spaced according to the mature size of the plants, on eight inch, 10-inch or 12-inch centers.
After transplanting, a controlled release fertilizer with a 14-14-14 (nitrogen, phosphorus and potassium) analysis was applied. Throughout the growing season, several liquid fertilizer feedings also were applied. Plants were watered on an as-needed basis that averaged between one and two times each week. The beds received between one-and-one-half and two-inches of water per application.
Seed industry representatives and home Gardeners teamed up to judge the plants on July 28. All plants were evaluated on the basis of foliage quality, flower quality and overall presentation.
The annual trials have been conducted at Colorado State's Plant Environmental Research Center since 1979, when fewer than 200 varieties were tested. In 1998, Colorado State University was chosen as one of two All-America Selection outdoor test Gardens in Colorado. That same year, outdoor pot trials were added to the regular bed plantings, adding diversity and thoroughness to the testing site. The trials have become one of the largest trial grounds in the Rocky Mountain region. In the 2000 growing season, approximately 945 varieties of annual flower cultivars were tested.
The trial Garden is managed by Colorado State's Department of Horticulture and Landscape Architecture in cooperation with a committee of industry representatives. Its location is typical of the high light intensity, dry conditions, erratic weather and large fluctuations between day and night temperatures found in the Rocky Mountain region. Last summer added extreme heat to these conditions. In Fort Collins a total of 38 days over 90 degrees F was recorded. This more than doubled the previous three-year average of 17 days with temperatures of higher than 90 degrees. The hot weather continued through mid-September, when it abruptly cooled. Frost hit Fort Collins on September 22.
The gardening public is welcome to visit the trials this season at High School Park on College Avenue and Remington Street in Fort Collins. For a complete research repot of the annual trial gardens, contact the Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523. There is a charge to cover the cost of printing, handling and shipping.
Photograph courtesy of Goldsmith Seeds.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010