CO-Horts: National Ornamental Grass Trials in Colorado

Posted by: Jane Rozum, Douglas County Extension

This time of year, while some perennials are looking a bit tired, there's a perennial that is just starting to put on its best show: Ornamental grasses. I’m not talking the cool-season Calamagrostis (feather reed grass) or Festuca (fescue) species, I’m referring to the beauties born on the Great American prairies, the warm-season Panicum (Switchgrass), and Schizachyrium (Little Bluestem) species.

Warm-season grasses wait until the ground warms in late spring to start growing; these grasses are no fools and would never get caught in a late season frost. They grow best and flower during the warmer months of the year; most start flowering in late July and August. They also have an amazing ability to withstand drought better than their cool-season cousins, making them more than worthy for our low water use landscapes in Colorado.

National Ornamental Grass Trials at Colorado State University

Dr. Mary Meyer from the University of Minnesota launched the National Ornamental Grass Trials in 2012, a three-year study where 17 sites around the country are growing 22 cultivars of warm-season grasses including many cultivars of Panicum (Switchgrass) and Schizachyrium (Little Bluestem). Not only will this study evaluate whether the grasses survive with minimal cultural inputs (horticulture-speak which means that plants don’t use much water or fertilizer), but also look at which plants thrive and possess desirable characteristics making them market-worthy for the nursery industry. Colorado State University is a collaborator in the trials, and 2014 is the second year of data collection for these grasses. At CSU, the grasses have received less than ½ the amount of water a bluegrass lawn would need to grow during the year as well as no fertilizer.

In 2013, the top performers at CSU included: Switchgrass cultivars ‘Shenandoah’, ‘Northwind’, ‘Thundercloud’ and Little Bluestem cultivar ‘Blue Heaven™’. Who will be a top performer this year? We won’t know until the data is collected later this month, but one thing is certain: these tough and beautiful grasses definitely will have a place in future low-water landscapes in Colorado.