Native Turf Grasses in the Demonstration Garden

A year ago, the Demonstration Garden at Ida Lee Park in Leesburg undertook to plant examples of turf grasses local homeowners might use in their suburban yards. Initially those included three cool weather grasses (tall fescue, fine fescue, and Kentucky blue grass), two warm weather grasses (Bermuda and zoysia), and two “native” grasses (blue grama and buffalo). The word native is in quotes because, while these grasses are native to the U.S., they are not native to Northern Virginia. No grasses are – which is the principal reason why homeowners have such difficulty with lawns in this area.

Buffalo and blue grama are warm weather grasses native to the Great Plains, from Montana all the way south to Texas. Both have characteristics that recommend them as turf grasses. They are hardy, draught resistant, and require little fertilizer. Both have been cited as environmentally-friendly substitutes for the turf grasses usually used in this area – especially for home owners seeking to create a meadow in lieu of a conventional lawn. Big box stores do not yet carry the seed, but commercial suppliers offer it via the Internet. Encouraged by these prospects, last spring the Demo Garden planted an eight-by-eight-foot plot of each grass.

The task did not initially appear daunting. According to our research, neither grass required anything special in the way of soil preparation. Both would tolerate a wide range of pH levels, and both would germinate within 7-10 days under “favorable conditions.” The only caution that we noticed in most references was the prospect of “cool season weed invasion.” We blithely planted the buffalo and blue grama seed that Debbie, our agent, had obtained for us from Virginia Tech. At that point, planting prairie grass didn’t look much more difficult than Kentucky 31.

Wrong. Although we provided the new seed beds ample watering, nothing happened. The seeds just sat there and stared back at us, quite content to remain idle in the cool spring weather. Then weeds began to appear. We did not pull them for fear of disturbing the grass seed. We waited. The weeds proliferated but the grass seed just sat there, sleepy in the cool spring weather. Then it hit us. These were warm weather grasses and it was still April! Closer research indicated that 70-degree temperatures were needed for germination. We were confronted by the “cool season weed invasion” that our research had warned us about.

That same research had suggested a solution for that problem: after preparing the seed bed, water and fertilize it to encourage the weed seeds to sprout. When they do, zap them with Round Up, then wait three or four weeks to plant the native grass seed. Of course, the Demo Garden is organic so the use of Round Up is not acceptable. Likewise, using a post-emergent 2,4-D based herbicide such as Weed-B- Gone is off limits. That left only one alternative if we were to save the grasses: hand weeding.

For the first year, we did that. We carefully pulled weeds, trying not to up root the grasses. It didn’t work for the buffalo grass. A vigorous stand of sedge did it in. The blue grama was more fortunate. It did get established and survived the heat of summer with little watering. By fall its 8-to-10 inch height had made it quite competitive with most weeds. Unfortunately, the blue grama tends to be tufted (see image at right), with an inch or two between tufts. That allows room for weeds, so the following spring we experienced a repetition of the dreaded “cool season weed invasion.” By May the blue grama tufts – still dormant in the cool spring weather – were hardly visible among the weeds. Back to hand weeding!

Pulling weeds is tedious. Given the effort that went into weeding our little eight-by-eight plot, we speculated that few Harry Homeowners would be willing to do so after putting in eight hard hours on the job. Maybe blue grama was not really suitable for suburban Loudoun County. We consulted with Debbie and she passed final judgment. Solarize it! The equivalent of horticultural euthanasia!

In May, we carried out the sentence. We turned over the bed, wet it down thoroughly, and then covered it with clear plastic sheets. The summer sun will raise soil temperatures beneath the plastic adequately to kill weed seeds, and the next grass we plant there will be free of that problem, at least initially.

I think our experience with native grasses indicates they would not now prove an acceptable substitute for turf grasses for most suburban homeowners. As warm weather grasses, they would be brown through much of the year. Plus their texture and growth habits don’t fit most homeowners’ current expectations for a “carpet of green.” And then there is that dreaded prospect of “cool season weed invasion.” But popular tastes will change as the imperatives of prudent ecology become evident. Their low maintenance and low irrigation advantages may yet make buffalo and blue grama – or some future hybrid of them – turf grasses of choice in Northern Virginia.

Jim Kelly, Loudoun County Master Gardener