Greener Roadsides

Nebraska's Wildflowers
Growing from a Prairie Heritage

Editor's Choice: a close-up of an attractive wetland native, Blue Flag, Iris virginica.

Art Thompson
Nebraska Department of Roads

Nebraska's roadside reestablishment program has been building since the early 1960's when we broke away from the brome grass traditions and utilized native grasses and legumes to stabilize our roadsides. To accomplish this, the seed producers had to increase their production, improve the germination rates, and certify new named varieties of native selections. By 1974, we began to incorporate wildflowers in our seed mixes in an attempt to reintroduce the diversity and native ecology of our prairie heritage. As a part of this heritage, wildflowers and native grasses are used to recreate the look and feel of Nebraska's native prairie on the roadside.

Our roadside program, which could be termed Integrated Roadside Vegetation Management, begins with careful planning. By selecting varieties, native and hardy to the area for erosion control, we are ensured that the seed will have an excellent chance of establishing. With over 10,000 miles of highways and 153,000 plus acres of right-of-way, roadside native vegetation benefits the state through the promotion of wildlife habitat, reduction of maintenance requirements, stabilization of soil, and protection of an emergency hay bank during times of drought.

Following all road construction, the roadsides are seeded with native grasses, as well as, native and introduced wildflowers. With the quantity of right-of-way we maintain and ever increasing maintenance costs, it is vital to create a landscape that will become as low maintenance as possible and enhance the adjacent landscape.

We have two classifications of seed mixes, which are used throughout Nebraska to re-establish our roadsides.

• The first mix is used adjacent to the paved surfaces and consists of shorter grass varieties, which are tolerant of deicing chemicals and regular mowing. These grasses are generally kept mown to a height of five inches and mowed out fifteen feet from the paved shoulder. If they are allowed to reach their mature height of twelve to eighteen inches, it generally does not create a safety concern.

• The second mix, which is utilized throughout the remainder of the right-of-way, consists of taller varieties of grasses and contains the majority of the forbs and wildflowers. After seeding, this area is mown up to three times a year for two years to control the growth of weedy species until the native plants are established. Upon completion of the establishment period, a limited mowing policy is implemented. Under this policy, a portion of the right-of-way is typically mowed once every five years in an effort to simulate the natural burns that would occur on the prairie. This mowing aids in reducing the litter and recycling nutrients back into the soil. Only one side of the roadway is mowed in a given year in an effort to maintain wildlife habitat in that area. Along with the environmental benefits of our reduced mowing, the requirements for grass care by our maintenance crews are drastically reduced, saving money and increasing the availability of manpower for other duties.

Site-specific seed mixes: The seed mixes, within these two classifications, are designed based upon the local soil, topography, and climate conditions of the project. The success of our seeding program is hinged upon the knowledge of these local conditions, careful planning, and quality installation.

To help ensure this quality, we have adopted the following measures:

• Cover crop seeding and erosion control materials are used to maintain the finish grade of a project until the permanent seeding can be installed and established.

• We require the contractor to use the best method of seeding for the establishment of the grasses and wildflowers on each project. Drilling is our preferred method, but only if it can be safely accomplished by the contractor. Broadcasting and hydroseeding can also be used with appropriate alterations in the seeding requirements.

• The seed must be a certified named variety and come from approved sources.

• The roadsides are fertilized at the time of seeding to ensure that essential nutrients get to the plantings in this very disturbed soil.

• All of the projects are mulched after seeding, with the mulch being crimped into the soil to resist wind.

• Native hay or straw is used for mulch with the new seeding. This mulch must be certified noxious weed free before it is accepted for use on a project. Some projects are restricted to native hay to reduce competition from the grain in the straw.

While preference is given to native wildflowers, not all of Nebraska's wildflowers are native. Some introduced variety's ability to adapt and flourish with the local conditions on a given site cannot be overlooked. This combination of native and non-native wildflowers provides changing color and interest along the roadway throughout the year. Whether it is their burst of color the spring after a project is completed or the seasonal changes in texture and color associated with an established roadside, wildflowers have become an integral part of our seeding program. Through careful planning and quality installation, we are ensured that wildflowers will flourish on our roadsides for generations to come.