Plan ahead for successful reseeding of perennial grasses

While most people entertain thoughts of planting seed in the spring, fall is the time to consider planting perennial pasture grasses. Seeding native or introduced perennial grasses is very different from seeding a grain crop or planting a garden. Most native grass is planted on dry-land, without irrigation, so the success of the seeding is dependent on naturally occurring precipitation, timing and a certain amount of luck.

Ellen Nelson
Larimer County Weed District

Consider how these grasses evolved to reseed themselves and you will understand why dormant-season seeding is used to establish perennial grasses. By this time of year, grass seed heads have matured, and can be knocked to the ground by passing wildlife or livestock, by heavy wind and even wind-driven snow later in the season. Not all of the seeds fall at once and some have developed mechanisms for dispersing with the wind or hitching a ride on animals’ coats. One way or another, the seeds find their way to the ground, where they may get trampled and ground into the soil by migrating animals, or perhaps covered with a thin layer of soil through the action of wind or water.

Perennial grass seed, whether native or introduced, is not designed to be planted very deep. Most seed is happiest at 1/4” to 1/2” deep. The most common reason seeds do not germinate is they are planted too deep. For this reason, a special no-till drill is generally used for seeding perennial grasses. A no-till drill is designed to handle different weights and sizes of native and introduced grass seed, to plant at the proper depth, and to seed into existing vegetation.

Perennial grass seed is not designed to be planted in to a “prepared” seed bed as is typical for a grain crop. The ability of seed to germinate and of seedlings to survive is related to sufficient moisture at the proper time and the benefits of shelter from the wind and sun provided by the existing vegetation balanced against the competition for moisture and nutrients from these same plants.

If you are considering a reseeding project, planning is important. The recommended dates for dormant season seeding are Nov. 1 through April 30. Before planting several tasks must be completed. First, control or eliminate most of the weeds in the area you want to reseed. In general, most grass seedlings are very susceptible to herbicide, and herbicide should be avoided on newly seeded areas for the first year. Your primary method of weed control in newly seeded areas will be mowing.

Plan to do your weed control prior to planting as many weeds can out-compete your grass seedlings. Second, if you have a lot of weeds, consider planting a cover crop before reseeding native grasses. A cover crop is generally an annual grass such as oats, triticale or sorghum, that is planted in the spring or early summer. These grasses will out-compete most weeds, can tolerate some herbicide, and when mowed provide the perfect “cover” for perennial grass seedlings that germinate the following spring.

The purpose of a cover crop is to out-compete weeds, provide stubble to collect and hold moisture that comes in the form of snow and conduct it down into the soil where it can nourish the newly planted perennial grasses, and to provide shelter from extremes of wind and sun that could desiccate grass seedlings. When using a cover crop it is important to either mow the cover crop before it produces seed, or select a sterile variety that will not produce viable seed. You do not want the cover crop to reseed itself and compete with your desired perennial grasses the following spring.

Many native grass species are found in northern Larimer County: western wheat, blue grama, sideoats grama, needleandthread grass, buffalo grass, slender wheatgrass, sand dropseed, green needlegrass and in some locations big and little bluestem. There are also many varieties of introduced perennial grasses that do very well along the front range. Local seed dealers offer prepared seed mixes suited for different locations and purposes.

The Fort Collins Conservation District recently purchased a Dew-Drop no-till drill, that is smaller in size and ideal for reseeding projects on smaller acreages. The Conservation District has generously made this drill available through the Larimer County Weed District for reseeding projects of 1 to 2 acres. In addition, the Weed District has a Great Plains no-till drill that is ideal for larger acreages.

The Larimer County Weed District website (http://larimer.org/weeds) lists commercial contractors for reseeding projects. For more information on reseeding, seed mixes, weeds, weed identification, pasture management, herbicide recommendations, and free site visits please contact the Larimer County Weed District at 970-498-5768.