Evaluation of Blue Grama Cultivars …

Evaluation of Blue Grama Cultivars as a Warm-season Option for Low Input Turfgrasses in Virginia

By Kevin Hensler, David McCall, Ph.D., Wendell Hutchens, and Mike Goatley, Ph.D.

Large areas of seldom used green space have been regularly maintained across recreational fields and out-of-play golf course roughs. Many have begun managing these spaces as low-input areas that are non-irrigated and rarely mowed to reduce labor costs and minimize resource inputs. Various fine fescues, cool-season cultivated turfgrasses, are the most common species used in these areas because of their growth habit. However, these grasses can struggle during prolonged periods of heat and drought stress that are common in many parts of Virginia and the MidAtlantic region. Blue grama, a warm-season, short-prairie grass native to the western U.S. ranging from Mexico to Canada has become acclimated to the western parts of Virginia.

Blue grama seedlings emerge and establish quickly, in as little as four to five days, and mature populations can survive under drought conditions more effectively than several more commonly used grasses. Growth characteristics vary widely by cultivar but some may prove to fill an important niche as a low-input alternative.

However, little is known about the survivability and growth characteristics of blue grama in Virginia, as most available literature focuses on adaptation to its native climate. Research is currently ongoing in our lab and is partially funded by the Virginia Agricultural Council (VAC#789) with support from the Virginia Turfgrass Foundation. Blue grama was chosen for further study because of its strong performance in previous studies at Virginia Tech in collaboration with the Virginia Department of Transportation.

To date, our research has included field, laboratory, and controlled environment studies mostly on campus in Blacksburg but also supplemented at the Virginia Tech Research Short Course of Independence Golf Club (IGC) in Midlothian. Objectives have included cultivar evaluation, optimal seeding rate and timing, and minimal moisture needs for seedling germination.

We have evaluated five cultivars of blue grama, including ‘Alma’, ‘Bad River’, ‘BirdsEye’, ‘Hachita’, and ‘Lovington’. From what we have seen so far, we lump the varieties tested into two categories: 1) shorter grasses that could be used in seldomly trafficked in-play areas such as golf course secondary or tertiary roughs and 2) outof-play areas that receive essentially no traffic (Fig. 1). The second group of varieties could be used in recreational areas such as park and recreational facility surrounds, out-of-play areas on golf courses, and along roadsides. Each group could serve an important niche in our area with little to no inputs.

Figure 1: Growth habit of Lovington

Figure 1: BirdsEye blue grama on 09 July 2021, six weeks after planting date.

Figure 1: Aerial view of growth habit of Lovington and BirdsEye blue grama on 20 August 2021, 12 weeks after planting date

All five cultivars listed above were seeded in May, 2021 at both the Virginia Tech Turfgrass Research Center (TRC) and at IGC. Irrigation was applied at seeding only with no additional inputs.

Both groups of cultivars have fairly similar establishment timelines, with quick germination and adequate coverage within 4–6 weeks after seeding (Fig. 2). The taller varieties generally reach acceptable coverage more rapidly because of the longer leaves, though these differences are relatively minor.

Figure 2

At this point, blue grama seed is quite expensive to the tune of $18–20 per pound when we purchased earlier in 2021, depending on supplier and cultivar. One of our next studies was to address seeding rate requirements to reach acceptable coverage, using a representative from our two growth types. Lovington and BirdsEye were each seeded at rates of 0.1, 0.5, 1, 2, and 4 lbs/1000ft2 (Fig. 3). As expected, higher seeding rates equated to more rapid establishment. Plots of Lovington seeded at 4 lbs/1000ft2 exceeded acceptable coverage (70%) within four weeks, while plots seeded at 2 and 1 lbs/1000ft2 exceeded this level within five weeks. A seeding rate of 0.5 lbs/1000ft2 took six weeks to reach acceptable coverage. Even the lowest seeding rate of 0.1 lbs/1000ft2 eventually got there, though it took 14 weeks. As with the cultivar screening, the shorter BirdsEye variety had similar establishment rates as Lovington but slightly slower.

Figure 3

As a warm-season grass, the logical timeframe for planting is during the summer when soil temperatures are warm. However, there is plenty of evidence to support spring and even dormant sprigging/seeding of more common grass species like bermudagrass and zoysiagrass. We conducted additional studies to determine the germination window for blue grama, with the first being under controlled conditions on a gradient table at a temperature range from 42°F to 103°F. Essentially no seed germinated at the temperature extremes, but we did see adequate germination of BirdsEye between 53°F and 92°F and of Lovington between 60°F and 92°F. We saw similar results in the field but also found that soil moisture after seeding was a limiting factor under natural conditions. Additionally, we found that planting earlier in the spring will work better than in the fall (Fig. 4). While initial germination was similar with May and September plantings, blue grama thrived as temperatures increased into summer while coverage rapidly declined in the fall as temperatures cooled.

Figure 4

We have learned a lot about blue grama in a short amount of time, but understand that there are many questions still unanswered. We will continue with both validation and new studies in the coming year to gain a better understanding of the uses and limitations of blue grama as a low-input, warm-season grass in Virginia.