Ornamental grasses are indispensable for today’s landscapes. Not only do they have low water, nutrient and maintenance characteristics, but they give a unique and naturalistic appearance in both commercial and homeowner landscapes. They can function as a screen or background plant, accent more colorful plants, or stand alone in groupings. It is no wonder that sales of these resilient grasses have risen 61% in the last 10 years.
The National Ornamental Grass Trials was launched in 2012. This three-year study at 17 sites around the country was coordinated by Dr. Mary Meyer at the University of Minnesota. Colorado State University participated in the trials and was the only site in the Intermountain West. Twenty-two cultivars of Panicum (Switchgrass) and Schizachyrium (Little Bluestem) were included in the trial. The trial evaluated whether the grasses survived minimal cultural inputs and also which plants thrive and possess desirable characteristics under Colorado weather conditions. All the grasses were watered at 50% of bluegrass reference evapotranspiration, which is about ½” of water per week, with no amendment to soil at planting or fertilizer for the duration of the trial. Wood mulch was added around the plants in 2013 to control weeds. Fall of 2015 was the last data collection.
Colorado State evaluated the plants using a landscape impact rating scale to rank each plant’s appearance and sustainability parameters. This scale ranks attributes such as growth habit, lodging, floral impact, winter injury and disease or insect damage. Overall, most of the cultivars did very well in the CSU trials. We’ve included photos and descriptions of the best of the trial plants over the three years of the trial.
Panicum virgatum ‘Dallas Blues'
· Selection from seedling in Dallas, Texas home landscape
· Broad steel blue to gray-green foliage, leaves ¾-1-1/2” wide; bold textured
· Purplish panicle inflorescence
· Mature height: up to 5 ½ feet
· Perennial Plant of the Year, 2014
· Upright, narrow growth habit ; possibly a substitute for Calamagrostis x acutiflora ‘Carl Foerster’
· Foliage blue/green, inflorescence green/tan
· Mature height: 5 feet
• Selected in Germany from seedlings of ‘Hanse Herms’
• Leaves initially green in spring, red in July, wine-colored in September
• Upright, broad growth habit
• Mature height: 4 feet in flower(tan)
Panicum virgatum ‘Thundercloud’
· Upright vase growth habit
· Wider, blue-green leaves up to 1 inch
· Pinkish panicle inflorescence give appearance of cloud above leaves
· Mature Height: 6 feet
· Upright, open growth habit
· Light blue foliage
· Fall color: Deep pink-burgundy with copper highlights
· Mature height: 2 feet
• Compact, upright growth habit
• Blue-green-gray leaf color
• Fall color- copper, mahogany
• Mature height: up to 2 feet