Controlling Warm Season Grasses

The establishment of native prairie grasses has occurred throughout our region for a number of years now. Most of these warm season grass plantings are being conducted by wildlife conservation organizations to benefit field-dependent wildlife that have suffered a steady decline in numbers, such as the bird species bob-o-link, nighthawks, meadowlarks, grasshopper sparrows, and shrikes.

Warm season grasses display most of their growth during the summer, between the months of June and August, hence their name. This is in contrast to most of the common agricultural pasture and grain crops that display maximum growth during the spring and fall of the year. Most of these cool season grasses were imported from Europe, and they have supplanted native grassland species in most of our agricultural areas.

Native prairie grasses have many attributes that make them more suitable for field-dwelling wildlife. Warm season grasses grow in distinct clumps, and most grow quite tall, reaching two to six feet in height. These grasses are very deep rooted with a fairly ridged structure, enabling them to stand erect during the winter months. The clumpy nature allows for open areas at ground level, permitting easier movement by small animals versus cool season grasses that form dense mats of grass that are difficult to navigate. Along with easier navigation, native grasses provide enhanced overhead cover to help shield small birds, chicks, and other wildlife from falling victim to birds of prey and other predators.

Warm season grasses also attract a more diverse mixture of insects than cultivated grasses, providing a more diverse diet for wildlife. The stout nature of these grasses also means that they won’t mat down during the winter months even when they are covered with snow, further enhancing wildlife cover. The deep-rooted nature of warm season grasses also makes them desirable for erosion control and as a buffer to take up nutrients before they can enter a waterbody or wetland. These plants are also fairly maintenance-free once they become established.

Some of the more popular warm season grasses that are being planted in Maryland include big bluestem, little bluestem, Indian grass, eastern gamma grass, and switchgrass. Often a mixture of wildflowers and native ferns will be planted along with the grasses to help approximate a native grassland community.

Some common wildflower mixtures include partridge pea, bee balm, plains coreopsis, spiderwort, and the venerable black-eyed susan. There are numerous publications that explain how to establish warm season grasses, available on the Internet. When establishing native meadows, it is important to control undesirable weeds until the grasses become established.

Another important consideration is to create a large enough planting to allow animals to escape predators. Smaller plantings can act as predator traps, providing animals a false sense of security from marauding predators. Most publications emphasize the need to remain patient, because it can take a few years for the grasses to become fully established. Once they do, they are often maintained by periodic burning to rejuvenate the grasses and rid the meadow of undesirable vegetation. Conducting warm season grass burns takes a lot of skill and it is best left to professionals.

Contained burning of warm-season grasses near MiddletownPhoto from Maryland DNR

Nature Note for 7/10/2016