Dahlia ‘City Lights Purple’ Best of Show

One of the most enjoyable ways for gardeners to get through the dark, cold days of winter is to begin planning next summer’s gardens. Over the next few weeks, we’ll look at plants – annuals, perennials, edibles, trees and shrubs – to consider for addition to your gardens this summer.

First, we’ll take a look at the top performers in Colorado State University’s 2019 flower trials.  The purpose of CSU’s trial gardens is to evaluate the performance of annuals and perennials under stressful Rocky Mountain growing conditions, which include intense sun, drying winds, severe hailstorms, large fluctuations between day and night temperatures and dry growing conditions. Sounds a lot like Nebraska! Plants are evaluated on vigor, abundance of flowers, tolerance to environmental stress, and disease resistance.

The trial gardens, located on CSU’s Fort Collins campus, are open to the public and are definitely worth a visit. The gardens are beautiful and plants are labeled, allowing visitors to stroll at will and decide which plants they like best.

Top Perennial Performers
One section of the CSU trial program focusses on newly released perennial cultivars (cultivated variety) – three years or less. Each cultivar is allowed to overwinter twice and is evaluated for the characteristics mentioned above. One of this year’s top picks is ‘Millenium’ ornamental onion.

Allium Millenium
Allium ‘Millenium’

‘Millenium’ plants develop a uniform mounded growth habit with the long linear leaves typical of alliums. Flowers are rosy-purple and long lasting, very attractive to bees and butterflies. Flower stems are strong and upright. In the CSU trials, flower stems did not lodge (fall over), even under continued overhead irrigation. Plants reach a height of 15-20 inches, with a spread of 10-15 inches.

Millenium is easy to grow in full or partial sun, with average soil. It’s available from several mail order nurseries, such as White Flower Farms, High Country Gardens, Walters Gardens and Proven Winners.

“Best Of” Annuals
Several annual selections were chosen with great characteristics worthy of consideration.

Best of Show – Dahlia ‘City Lights Purple’ (pictured above) has deep burgundy, double flowers darkening almost to black toward the center of the flower. Foliage is a dark greenish-purple. Plants are compact with multiple branches, blooming from July to October. Plant height is 18-24 inches with a spread of 15-18 inches. Dahlias are not winter hardy in Nebraska, but their tubers can be dug up in fall and overwintered indoors for planting again the following year.  Available from White Flower Farms.

Begonia T Rex ‘Ruby Slippers’

Best Novelty – Begonia T Rex ‘Ruby Slippers’ has very large red leaves with nearly black markings along the main veins and silvery edges. Rex begonias are grown primarily for their striking foliage, although they do produce small flowers. Plants are vigorous with a uniform growth habit and will add great color to shaded areas of the landscape. Provide plants with some protection from the wind to protect the large leaves from physical damage. Plant height is 16 inches with a spread of 16 inches. Find retail location from Terra Nova Nurseries.


Best New Varieties
Several great new cultivars were identified among common annual flower species. For pictures and more information, visit http://www.flowertrials.colostate.edu/.

  • Angelonia ‘Carita Purple’ – deep purple flowers are very prolific on showy plants. Plants have a superior overall appearance even during the hottest part of summer.
  • Bidens Campfire Flame
    Bidens ‘Campfire Flame’

    Begonia ‘Tophat Pink’ – this vigorous begonia grows well in sun, looking great in ground beds or containers. Plants are covered with flowers in rosy-pink.

  • Bidens ‘Campfire Flame’ – flowers in beautiful shades of orange, red and yellow from early summer into September. Growth habit is very uniform and plants
    Petunia Headliner
    Petunia ‘Headliner’

    provide a very striking effect in containers.

  • Petunia ‘Headliner’ – flowers have bold coloration with soft creamy yellow and a very dark purple star-shaped eye. Plants grow vigorously and hold up well in heat.


Images – all from Colorado State Flower /

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