Site Preparation

Proper soil preparation is the single most important factor in the success of your prairie planting. The planting area must be completely free of weeds. Existing weeds will compete with the prairie seedlings for nutrients, water and sunlight. If not controlled, they can delay or prevent the growth and maturation of your prairie. Whether you're planting seeds or transplanting plants, adhere to the following guidelines to ensure good results.

The First Step
Lawns
Old Fields
Herbicide
Using Cultivation Only
Corn, Soybean and Small Grain Fields
Erosion-Prone Sites
Newly Disturbed Soils

First Step

The first step in soil preparation is to eliminate the existing vegetation. All weeds and grasses on the site must be killed, using smothering, cultivating, herbiciding or combination of these techniques. On small areas of a few thousand square feet or less, smothering weeds on the area is simple, effective, and requires no chemicals or special equipment. Smothering involves covering the soil surface with black plastic, old rugs, pieces of old plywood, or a thick layer of newspapers covered with leaves or grass clippings. This should be left in place for a full growing season in order to kill the plants underneath. An exception to this rule is lawns, which can usually be killed in two months using smothering. However, if perennial weeds are present in the lawn, a full year of smothering may be required to kill them.

If using herbicides, we recommend using a broad spectrum, non-persistent herbicide such as glyphosate (ie. Roundup, Ranger or Kleenup). If pernicious perennial weeds such as Canada Thistle, Canada Goldenrod, Horsenettle, or woody shrubs and vines are present, it may be necessary to add a broadleaf herbicide and a surfactant to the Roundup mixture to kill these tough weeds. When using herbicides, ALWAYS READ THE LABEL, and follow the manufacturers instructions.

If you prefer not to use herbicides, you can employ smothering, smother cropping, or cultivation. A variety of implements are available to prepare your soil using cultivation. A sod cutter, rototiller, tractor-mounted rototiller, rotovator, or farm implements such as a plow, disk or harrow may be used, depending on the size of the area to be planted.

Lawns

The easiest way to prepare a lawn for planting is to treat it with Roundup herbicide in early fall or mid-spring when it is actively growing, or to smother it for 2-3 months during the growing season. In Autumn, after the lawn is dead, prairie seed can be machine-planted using a no-till seed drill. The seed can also be hand broadcast on top of the dead sod. It will work its way down into the soil over winter and germinate in the following spring. This hand broadcasting technique only works in fall, as winter is required for the seed to settle into the soil below. DO NOT ATTEMPT THIS METHOD IN SPRING. When seeding in spring, the dead sod will require thorough tilling to break up the thatch, or it can be removed using a sod cutter, as below, after herbiciding. Burning off the dead lawn after spraying can help reduce thatch, making tilling easier.

To create an instant seedbed without herbicides, the upper 2-3 inches of sod can be removed using a sod cutter. This typically creates a nearly weed-free planting bed that can be seeded or planted with transplants. Be aware that the area will be lower than the surrounding lawn after sod removal. Sod cutters can be rented for this procedure. If perennial weeds are present in the lawn, these will likely not be removed by the sod cutting procedure, and will likely pose a threat to your planting.

To remove an existing lawn using cultivation, rototill the area 2-3 times, approximately 1 week apart. If rhizomatous perennial grasses such as Quack grass or Johnson grass are present, a year-long tilling program may be required to eliminate them.

Old fields

Old fields are areas that have been left fallow for a year or longer, and have grown up to weeds. These can be difficult to prepare, due to the presence of a variety of perennial weeds. An old field usually requires one to two full growing seasons to prepare properly. This may seem long, but a little patience at this stage is essential for a successful planting.

Herbicide

To herbicide an old field, begin by mowing everything down in late July or early August. Allow vegetation to re-grow to a height of about one foot. Apply a glyphosate herbicide (Roundup) in early to mid September.

The following year, spray with Roundup three to four times throughout the season, every six to eight weeks. The first application should take place in mid spring, the second in early to midsummer, the third in late summer to early fall, and possibly a final mid autumn application. The area must be completely free of perennial weeds prior to seeding. If not, a further spraying will be required the following spring, and the seed can be planted one week after spraying, in late spring or early summer.

Using Cultivation Only

you will need to cultivate old fields beginning in spring and continuing through fall. Cultivate every two or three weeks at a depth of 4-5 inches using a harrow, springtooth, or rototiller to kill weeds. Be religious about this. If you are fighting rhizomatous, perennial weeds, waiting longer than 2-3 weeks will allow these weeds to recover. For some species, such as Quackgrass, cultivating in intervals greater than 2-3 weeks may actually increase its density. If weeds are not completely eliminated after one year of this treatment, a second year may be necessary. This is a labor-intensive process, and every cultivation cycle brings up new weed seeds to the soil surface where they can germinate. Cultivation is not recommended for slopes or other erosion prone areas.

Corn, Soybean, and Small Grain Fields

These typically have fewer weeds compared to old fields, and usually require less preparation. Corn, bean and grain fields with few weeds can be sprayed with glyphosate herbicides once in late spring and seeded. If small grains have been harvested in summer, spray the field once or twice to kill weeds, and seed that fall or the following spring. If problem perennial weeds are present, site preparation will require a full year or longer, the same as for Old Fields.

If you are planting many acres of prairie and live in an agricultural area, you may be able to enlist the assistance of a local farmer to prepare your old field. Rent the land to the farmer, and have it planted to corn the first year, followed by soybeans the second year. This cropping sequence will eliminate almost all perennial weeds, and costs you nothing. Please beware that the farmer will need to use certain herbicides in order to control weeds and ensure a good crop. Make sure that no persistent herbicides, such as Atrazine, are applied that could affect the germination of your prairie flowers or grasses.

Agricultural fields can be prepared without herbicides, using cultivation for a full growing season to kill weeds. If rhizomatous perennials are present, work up the soil for at least one year, as described for Old Fields. Once all existing vegetation is eliminated, the final seedbed should be leveled using a drag or disc, or the area can be seeded using a no-till prairie seed drill.

DO NOT plant wildflowers in fields treated with Atrazine within the last 2 years. While some prairie grasses can tolerate low levels of Atrazine, the prairie flowers cannot tolerate any. Atrazine breaks down in 1-3 years depending upon soil type, precipitation and the amount originally applied. If you have a field that you suspect has Atrazine carry-over, a smother crop of corn or sorghum can be planted to hold your soil for one year and control unwanted weeds while the Atrazine breaks down, or the field can be sprayed with Roundup three times during the growing season to control weeds. Warm season grasses such as the Bluestems, Indiangrass, Sideoats Grama and Switchgrass can all tolerate up to two pounds per acre of Atrazine. Cool season grasses and prairie wildflowers are killed or severely damaged by this highly toxic herbicide.

Erosion Prone Sites

Precautions need to be taken on erosion prone sites. To avoid runoff and soil loss the site should not be left un-vegetated for any length of time. Cultivation should be kept to a minimum. Preparing your site solely by cultivation may create unwanted erosion problems. Slopes should be planted immediately following soil preparation. Plant a nurse crop of oats or annual rye with your prairie seeds, and apply 1-2 inches of weed-free straw mulch. (Please see Annual Rye for information on ordering nurse crops.) Better yet, use a light erosion blanket containing straw or light excelsior over the seeded area, staked into the soil to hold it in place.

If you are unable to plant your site immediately, it can be stabilized for a few weeks or months by planting a cover crop of oats at 4 bushels (128 lbs.) per acre, or annual rye at 50 lbs. per acre. When ready to plant your prairie seed, till the oats or rye under, or spray with Roundup herbicide to kill it and any weeds that may have grown up. Wait one week, and plant into the dead grass using a no-till seed drill. Seed can also be scattered directly into the dead cover crop in the fall, and it will work its way down into the soil in winter and germinate in the following spring.

Newly Disturbed

Areas of bare soil resulting from recent construction may be essentially weed-free. They could also contain living weedy plants that will re-sprout and grow, or a veritable Pandora's box of weed seeds! If the source or weed status of recently disturbed soil is unknown, it is best to wait and see what comes up and kill any weeds prior to planting. The soil should be leveled and seeded to a cover crop of oats or annual rye to prevent erosion. When weeds emerge and grow to a height of one foot, the area should be sprayed with Roundup herbicide. If problem perennial weeds appear, the area will likely require a full season of treatment. An alternative to herbicides is smothering for one year to kill weeds, or cultivation for a full growing season.

A well prepared site is half the battle when establishing a prairie planting. By removing the existing vegetation, and providing a suitable seed bed for germination and seedling growth, you are well on your way to a successful planting. Once established, your prairie will bring you years of enjoyment with a minimum of maintenance!