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 look at the top performers in Colorado State University’s 2021 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 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 Performer
One section of the CSU trial program focusses on newly released - three years or less - perennial cultivars (cultivated variety). Each cultivar is allowed to overwinter twice and is evaluated for the characteristics mentioned above. One of this year’s top picks is ‘Firefly Sunshine’ Achillea, commonly known as yarrow pictured above.
‘Firefly Sunshine’ plants have a compact upright growth habit. In the CSU trials, flower stems did not lodge (fall over), even under continued overhead irrigation. The flowers are bright yellow, which contrasts well against dark green foliage. It was also noted during the trials, that plants did not spread themselves around the garden as other yarrows are prone to do. Plant in full sun with average garden soil. Avoid very rich soil. Plants reach a height of 28-30”, with a spread of 24-28”.
Once the initial flush of flowers has faded, cut plants back by half and allow them to regrow for another round of color. Available from Proven Winners, provenwinners.com.
“Best Of” Annuals
Several annual selections were chosen with great characteristics worthy of consideration. Nurseries offering these plants are listed if this information was available. If no nursery is listed, the plants may not be available for the 2022 growing season but check with your local nursery for more information.
Best of Show – Rudbeckia ‘Sunbeckia Ophelia’ has very large yellow flowers, which glow in the sun and create a solid mass of eye-catching color in the garden. This annual black-eyed Susan requires no pinching. New layers of flowers cover up older ones, in effect “burying the dead”. Plants reach a 20-24” height and 15-20” width. Choose a full to partial sun location with well-drained soil. Pictured above right.
Best Novelty – Heliotropium ‘Augusta Lavender’ has soft lavender flowers with a yellow eye, which are quite showy and bring a light fragrance to the afternoon landscape. Heat and humidity tolerant, it performs best in full to partial sun locations. Plants have good uniformity, reaching 12-24” height and 24-36” spread, with a mounded growth habit. A favorite of pollinators! Available from Proven Winners.
Best New Varieties
Several great new cultivars were identified among annual flowers, including a few highlighted below. For pictures and more information, visit http://www.flowertrials.colostate.edu/.
Angelonia ‘Archangel Dark Rose’ – Plentiful and upright, the dark rose flower spikes on these vigorous plants lasted late into the summer season. Excellent performance in both containers and ground plantings.
Bidens ‘Brazen Imperial Luck’ (right) – Vigorous and highly branched plants create a solid mound of flowers across the canopy. Flowers are a uniform bicolor, with a center of deep golden yellow and rich saturated red at the petal tips. These beautiful plants have the unfortunate common name of beggar’s ticks. Flowers are very popular with bees!
Calibrachoa ‘Cabaret Good Night Kiss’ (left) – Its flowers are a stunning bright pink with a very dark purple center and yellow inner throat. The color is intense and vivid against its dark green foliage. Plants create a uniform, dense mounded habit. Plant height is 6-10” and the recommended spacing is 10-12”. Available from White Flower Farms.
Dahlia ‘City Lights Purple’ is a repeat winner from 2020 and a Consumer Day evaluation winner. It 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.
Images - all from Colorado State Flower Trials.