Preparation of the seedbed is one of the most important steps in a prairie restoration. Proper preparation will reduce weeds, facilitate planting, and provide a suitable bed for seed germination. A good seedbed will increase the success of a prairie planting while a poor seedbed will promote failure.
If you are planning a spring planting, begin seedbed preparation in the fall prior to planting the following spring. Small parcels can be prepared with a garden tiller, but larger tracts, one-quarter of an acre or larger, will require the use of large farming implements. Preparation of the site in the fall will damage the root systems of perennial weeds and expose them to freezing temperatures and the dehydrating action of winter winds. In the following spring, the ground should be worked at a shallow depth at least twice to break up clods and eliminate annual weeds.
Large plantings can utilize a disc to cultivate the soil. Final ground preparation immediately prior to planting can be done with a cultipacker, a disc-like farm implement that cultivates only the upper few inches of soil. Once again, a garden tiller can be used on the smaller parcels. Be sure to cultivate only the upper few inches of soil. Deep cultivation exposes more weed seed, eliminates the firm underbase which is necessary for successful prairie establishment and may cause the prairie plant seeds to be planted several inches deep, making it impossible for the seedling to reach the surface.
If the site selected for the prairie planting has a dense sod of fescue, bluegrass or orchard grass, or some other cool-season perennial grass, you should consider the application of a short-lived, non-selective herbicide such as Roundup (glyphosate). A two percent solution of this herbicide is sufficient to kill most grasses and broad-leaved plants. The application of this herbicide should be made when the weeds or grasses are growing rapidly to be most effective, but good results can be obtained as long as the plants are actively growing. If this is not done, portions of the plants remaining above ground will re-establish themselves and create weed problems in the future. As with all herbicides, be sure to read the label carefully.
If you do decide to use an herbicide, use a non-persistent type and allow several days to elapse (one or two days with Roundup) before final soil preparation. A persistent herbicide could damage the prairie plants. By allowing several days to elapse after the application of the herbicide, you are assured of little or no herbicide carry-over.
The use of no-till drills in prairie establishment is increasing because of the time, reduced erosion, and cost savings of this method. With the no-till procedure it is possible to plant directly into an agricultural field or a site with a dense sod without the plowing, discing and other site preparation of the traditional planting methods. One of the big advantages of no-till planting is that it does not disturb the soil very much, ensuring the firm underbase necessary for successful plantings. Prairie plant seed must be planted within one-half inch of the soil surface. If the seeds are planted deeper, the planting runs the risk of failure because the developing seedlings are not vigorous enough to grow through several inches of soil.
If the planting is going into an agricultural field, first make sure that the soil is free from herbicide carry-over that may be harmful to germinating prairie plants, especially the wildflowers. If the field has high, standing corn stubble, shred the stalks so they will not interfere with the colters or planting devices of the prairie seed drill. Soybean stubble generally does not present a problem for no-till planting.
One of the first tasks to be completed is weed control. If the planting site is an abandoned agricultural field, allow the vegetation to grow to a height of about six inches and then spray it with a non-selective herbicide such as Roundup. A two percent solution will be sufficient to kill most herbaceous plants, including agricultural weeds. If weeds become a problem after the planting, they can be mowed at a height of six to eight inches to reduce the competion with the developing prairie plants. If only parts of the field have concentrations of weeds, mow these areas and leave the rest of the field undisturbed.
Like with home gardening or large scale agriculture, planting dates for prairie seeds are relative. The scheduled planting date should allow for shallow tilling or discing of the plot to eliminate weeds once the soil warms up in the spring. The ideal spring planting date on a statewide basis includes a two-month period from April 15 to June 15, with the earliest planting being made in the southern part of the state. Plantings made after the middle of June run the risk of encountering hot, dry weather which will reduce seed germination and seedling survival.
It is also possible to plant during late September, October or November, thus allowing the seeds to stratify naturally in the soil. If you decide to plant in the fall, be sure to plant late enough so that the seeds germinate the following spring. The freezing temperatures of winter could kill the young seedlings if planted too early.
The seeding rates per acre may vary according to your objectives for the planting. If you want a pure stand of grass, a seeding rate of 8 to 10 pounds per acre should be sufficient for this purpose. If you desire a mixed stand with numerous prairie wildflowers, reduce the amount of grass seed to 2 to 4 pounds per acre, particularly the larger grasses such as Indian grass and big bluestem. Increase the amount of wildflower seed until the mixture is about 60% grass and 40% wildflowers by weight (Rock 1977). In addition to reducing seed of the big grasses, also reduce the amount of seed of downy sunflower, false sunflower, drooping yellow coneflower, and new England aster. These plants are very prolific seed producers, and they will crowd out more desirable prairie plants.
By using a seed drill specially made for light fluffy seeds such as those of most prairie plants, it is possible to reduce the amount of seed required to complete the planting. Several commercial drills such as Truax, Miller, Great Plains, Tye and Marliss are made specially for this purpose, and most of these also have no till features.
It is also possible to further reduce the volume of the grass seed by utilizing a process known as "debearding." In this procedure, the seed of big bluestem, Indian grass, or little bluestem is processed in a machine which removes the awns or "beards." The removal of the awn permits the seed to pass through seeding devices more easily. A comparison of seeding rates for some grasses planted in pure stands is given below. If the seed that you purchase has been debearded, reduce the amount listed by one-fourth.
When planted together, the total weight of the grasses should not total more than 6 pounds. This is a recommendation. The ratio of grass to forb seed will often be a matter of personal preference, seed availability and cost. Some individuals prefer a planting where forbs are predominant and conspicuous. The wildflowers have a great aesthetic appeal throughout the growing season.