Surviving three summers and two winters in Colorado’s harsh climate, nine standout perennials have earned the title of “Top Performer” in Colorado State University’s Perennial Trial program.

Evaluating Perennials in the Rocky Mountains

The purpose of the trial garden is to evaluate new plant species and cultivars under the unique Rocky Mountain environmental conditions. Plants are evaluated for vigor, uniformity, floriferousness, and tolerance to environmental and biotic stresses. The CSU Perennial Trial program is designed to test newer perennial cultivars introduced in the past three years or less. Entries in this trial are grown for three summers and two winters before they are switched out for new entries.

High resolution images of this year’s top performing perennials can be found here.

2024 CSU “Top Performer” Perennials

Delgenius™ ‘Chantay’ Delphinium

Delphinium hybrids
Pacific Plug and Liner

Rich, robust lavender-dusty antique pink spikes make this delphinium a showstopper. Blooming once in late spring and again in early fall, ‘Chantay’ displayed lush green foliage and impressive floral density throughout the season. Just be sure to offer support, as their blooms can become heavy.

‘Orchid Frost Grande’ Lamium

Lamium maculatum
Plant Haven

This groundcover is an upgraded classic that delivers bigger orchid-pink blooms and lush silver-variegated foliage. Its tidy growth habit and adaptability to sun and shade made it an all-season performer in trial beds and containers.

‘Evening Sun’ Missouri Evening Primrose

Oenothera missouriensis
Darwin Perennials

A native standout, ‘Evening Sun’ glowed with bright yellow blooms that lit up the landscape from afternoon through evening. With pollinator appeal, drought tolerance, and low stature, it became a low-maintenance favorite for hot, dry sites.

‘Jelena’ Russian Sage

Perovskia atriplicifolia
Dümmen Orange

Whether in full bloom or not, ‘Jelena’ maintained its structure and charm. Growing to about 3–4 feet in the CSU beds, it resisted flopping even under irrigation. With lavender-blue flowers and soft gray-green foliage, it attracted pollinators and admirers alike.

‘Goldblitz’ Black-Eyed Susan

Rudbeckia fulgida var. Sullivantii
Kieft Seed

An earlier bloomer than ‘Goldsturm,’ ‘Goldblitz’ was praised for its vigor, uniformity, and season-long color. It stood tall and healthy with dark green foliage and pollinator-attracting blooms from summer through fall.

‘Conga Line’ Stonecrop

Hylotelephium telephium
Terra Nova® Nurseries

Put your garden in motion with this high-energy sedum. ‘Conga Line’ danced from deep green to purplish hues as summer progressed, topped with peach-cream flower clusters. It stayed upright, endured dry spells, and brought pollinators to the party.

‘Skyward™ Blue’ & ‘Skyward™ Pink’ Speedwell

Veronica longifolia
Darwin Perennials

A dynamic duo of vertical colors, these speedwells sent up fireworks of blue and pink blooms from late spring into fall. Their clean, mildew-resistant foliage and long bloom window made them reliable head-turners all season.

‘Pristine® Princess Pink’ Beardtongue

Penstemon barbatus var. praecox
Dümmen Orange

With bubblegum-pink tubular flowers and lush green foliage, this native penstemon was a hummingbird magnet. Its upright stems held strong even in the wind, and once established, it proved itself a stunning, waterwise choice.

About the Trial Garden

CSU’s Flower Trial Garden, which draws thousands of visitors annually, relies on student gardeners, volunteers, industry supporters, and experts who help provide detailed plant performance analysis. Colorado State Extension Master Gardeners play an essential role in the planting and maintaining the garden.

The outcome of this research is valuable to 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 Perennial 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 green industry companies.

Performance Evaluation

Photos and data on plants and flowers were collected bi-weekly from May to early October. Dead plants in the trial were not considered in the bi-weekly evaluation; thus, the ratings only reflect the live plants.

The Perennial Trial subcommittee members also evaluated and wrote comments for each plant variety in June, July, August, and September. Plants and flowers were rated 0-5 using the following scale:

• 0 = Dead/No flowers
• 1 = Poor: Plants are very sick or dying, extremely few flowers
• 2 = Below Average: Plants are unattractive in some form, i.e., leggy growth habit, chlorotic or low vigor, flowers are few and occurring sporadically
• 3 = Average: Plant appearance with growth characteristics that would be expected for the time of season; flowers would be few but uniform across the plants
• 4 = Good: Plants look attractive (foliage, growth habit, etc.); flowers are blooming strong and showy
• 5 = Excellent: Plants are very healthy and uniform; flowering is impressive

The Top Performers are selected based on their overall high ratings after the three years. A special committee of local industry horticulture professionals meets to discuss the results and ensure the best of the best is highlighted from our trials.