Colorado State University has announced its “Top Performing” perennials.

The results of the 2024 CSU Perennial Trial program highlight nine plants that flourished amid harsh winters and arid summers.

“The goal is to basically see how well they perform at higher altitudes, 5,000 feet or so,” said Chad Miller, director of CSU Trial Gardens. “You go from summerlike in the morning, to almost winterlike in the afternoon, with drastic changes. So it really does give the plants a solid test in the environment.”

When selecting the top contenders, researchers review monthly evaluations taken from April to September that report plant performance. Factors can include overall foliage, survival, color, flowering power, disease prevalence and water usage — things a homeowner or gardener would be interested in knowing.

The plants studied in the trial garden are new to the market, usually released within the past five years.

“The trials not only help consumers, like the average homeowner coming by to look at the trials, but trials also help our industry professionals in helping them select what they might want to grow,” Miller said. “One of the major things about plants is people want color. So, perennials that have longer bloom periods or reblooming periods, and flowers are big and bold.”

Delgenius “Chantay” Delphinium (Delphinium hybrids) by Pacific Plug and Liner

These blooming rods distinctly characteristic of Delphiniums proved a strong competitor among the trial garden. Blooming in late spring and again in early fall, the flowers have a pretty, pinkish-purple orchid color. The trial found the plant to have lush green foliage and plentiful, dense flowering — so much so that the blooms can become heavy and might need support throughout the season, according to the trial.

“Orchid Frost Grande” Lamium (Lamium maculatum) by Plant Haven

The rich purple color of the small, bell-shaped flowers of this Lamium plant pops against its silver foliage. Described as having a “tidy growth habit,” experts found the plant adapted well to sun and shade, making it a star performer throughout the season. The little flowers bloom profusely in mid-spring and occasionally throughout the summer.

“Evening Sun” Missouri Evening Primrose (Oenothera missouriensis) by Darwin Perennials

These delicate yellow flowers, described as a “native standout,” blossomed throughout the afternoon and into the evening. This primrose is noted for its strong pollinator appeal (a favorite of night-flying moths), drought tolerance and low stature. This is a low-maintenance perennial option for Colorado.

“Jelena” Russian Sage (Perovskia atriplicifolia) by Dümmen Orange

The “Jelena” Russian Sage is an airy plant speckled with bright blue and lavender flowers. It stands taller than other top-performing perennials at about 3-4 feet, maintaining its structure and resisting flopping throughout the season. The spacious plant was also reported to attract pollinators.

“Goldblitz” Black-Eyed Susan (Rudbeckia fulgida var. Sullivantii) by Kieft Seed

This classic yellow flower received high marks in the trial for its “vigor, uniformity and season-long color.” The pollinator-friendly plant bloomed from summer through fall, standing healthy with dark green foliage, a healthy contrast to the vibrant yellow petals.

“Conga Line” Stonecrop (Hylotelephium telephium) by Terra Nova Nurseries

A hardy succulent, this sedum plant performed well in Colorado’s sunshine and arid soil. The deep green, moisture-storing leaves stayed strong throughout the summer as blooms showcased more muted peachy-colored flower clusters.

“Skyward Blue” and “Skyward Pink” Speedwell (Veronica longifolia) by Darwin Perennials

Both versions of these Speedwell flowers provide vivid hues of pink and blue, respectively. The towering flowers bloom from late spring into fall with “clean, mildew-resistant foliage.” These are a good plant for gardeners looking for striking color all season long.

“Pristine Princess Pink” Beardtongue (Penstemon barbatus var. praecox) by Dümmen Orange

Described as a “hummingbird magnet,” these bright fuchsia tubular flowers are a bright addition to gardens. The lush green foliage held its structure even in the wind, and in addition to being the choice of pollinators, was also noted for its water-saving qualities.