Seeding a Prairie Planting

A prairie planting is a long-term investment in your landscape, which requires careful planning. Since a variety of site conditions may be encountered when seeding an area, it is not possible to write a standard "recipe" for site preparation and planting procedures. However, we have developed specific Guidelines for Success, based upon our many years of experience. If you have questions, please call us at 800-476-9453 Monday through Friday, 8 AM to 5 PM Central Time, or   e-mail us. We are here to help you ensure the success of your prairie planting!

Site Preparation Methods

To prepare your site for planting, you must first remove the existing vegetation. This may consist of perennial weeds, annual weeds, or both. Existing weeds will compete with prairie seeds for nutrients, moisture, and sunlight. Although it is nearly impossible to remove all annual weed seeds from the seedbank stored in the soil, it is crucial to kill and/or remove perennial weeds and rhizomes before planting. Perennial weeds such as Quackgrass, Bromegrass, Canada Thistle, Canada Goldenrod and Red Clover can inhibit the growth and development of your prairie. Eliminating all perennial weeds prior to seeding is essential to success with your prairie.

Site preparation options vary according to the vegetation type that you are converting to a prairie planting:

Lawns

Smothering

1. Cover the site with either black plastic, old carpet, plywood or a thick layer of leaves or newspapers, held in place to prevent blowing.
2. Leave in place for a full growing season and remove in fall or the following spring.
3. Plant into a prepared bed (see the specifics in section II).

Sodcutting

1. Remove the top two to three inches of grass and soil using a sod-cutter.
2. Till lightly and plant into a prepared seed bed.

Cultivating

1. Cultivate with rototiller, cultivator, or similar tool. Do this two to three times at one week intervals to kill the lawn. Remove clumps of sod and thatch to create a smooth seed bed.
2. If perennial weeds are present in the lawn, cultivate for a full growing season, at intervals of every two to three weeks. This should kill both the lawn and the perennial weeds.
3. Plant into a prepared seed bed after all weeds have been killed.

Herbiciding

1. Apply a glyphosphate herbicide (such as Roundup, Kleenup, etc.) when the lawn is actively growing (in fall or spring).
2. When the grass has turned brown, turn the soil under to prepare for seeding. Remove clumps of sod and thatch to create a smooth seed bed. Plant immediately.

Old Fields

Fields that have been abandoned and allowed to grow up into grasses and weeds require at least one full year for proper site preparation. Two years of weed control is even better, due to the presence of established perennial weeds and weed seeds in the soil. Do not rush site preparation in old fields. Kill all the weeds first!

Herbiciding

1. Mow and rake or burn the existing vegetation to the ground in late fall or early spring.
2. Apply a glyphosphate herbicide (such as “Roundup”) three times throughout the growing season at 6-8 week intervals when plants are green and actively growing. (mid-spring, mid-summer, early fall).
3. If perennial weeds are still present on the site after a full year of herbiciding, do not seed. Leave the soil undisturbed over winter, and apply one more herbicide treatment in late spring of the following year to kill any remaining weeds. If in doubt, wait, spray for a second year, and seed in the fall.
4. When all the vegetation is dead, work the ground to create a prepared seed bed. Plant seed according to directions in Section IV below.
5. If planting in fall, the seed can be scattered into the dead vegetation without tilling so long as exposed soil is visible below the vegetation. The seed will work its way down into the soil over winter, and germinate the following spring. This is a “Dormant” seeding. Fall dormant seedings typically result in higher germination of wildflower seeds, but lower germination of warm season prairie grasses. Spring seedings result in higher germination of warm season prairie grasses, and somewhat lower germination of certain wildflower seeds.

Cultivating

1. Mow and rake, or burn off the existing vegetation to the ground in late fall or early spring.
2. Cultivate to a depth of four to five inches every two to three weeks from spring through fall.
3. Before planting, make sure all the existing weeds have been killed. This procedure may require two consecutive years of cultivating to kill pernicious, noxious weeds.
4. Plant in fall or the following spring into a prepared bed.

Existing Fields of Corn, Soybeans, or Small Grains

Before planting into corn fields, test the soil for persistent agri-chemicals such as Atrazine. If present, Atraxine can kill germinating prairie wildflower seedlings. Use this simple test: Grow ten oat seeds in a pot with the cornfield soil. In another pot, grow ten oat seeds in potting soil, or unaffected garden soil (this is your experimental “control.”) When the oats reach a height of about four inches, those growing in Atrazine-laden soil will stop growing and turn yellow. Oats growing in untreated soil will continue to grow, without yellowing. Compare the oats growing in the cornfield soil with those in the untreated “control” soil to make sure that any positive results for Atrazine are not shared by the oats in the untreated soil.

Herbiciding

1. Spring: Spray once in mid to late spring, wait 10 days and plant into a prepared seedbed. This will kill annual weeds. If perennial weeds such as Quackgrass, Bromegrass, Canada Thistle, etc. are present, treat the field with Roundup three times throughout one full growing season, at six to eight week intervals (same as for Old Fields in Section B above).
2. Fall: Spray once after the crop is removed. If weedy vegetation is still actively growing, wait 10 days and plant into a prepared bed. If the crop is removed late in the season, wait until spring to spray the field when weeds are again green and actively growing. If problem weeds are present on the site, treat the field as an Old Field, and treat with herbicide three times, at six to eight week intervals, for one full growing season (same as for Old Fields in Sections B above).

Final Seed and Plant Bed Preparation

Just prior to planting, the soil should be prepared according to the type of planting method used.

1. Seeding by hand broadcasting, or mechanically using a Brillion drop seeder or similar implement: Requires a well-tilled, finely graded surface. A Brillion seeder is excellent for seeding onto tilled up soils on areas of one half acre or larger. Its heavy cast iron packing wheels ensure firm seed to soil contact.
2. No-till drills or slit seeders (Tye, Truax, etc): Requires a smooth, level soil surface, but little or no tilling. Tilling will only expose more weeds from the soil below, and is not recommended when using no-till drills and slit seeders.

A Final Pre Planting Tip

If planting in late spring or early summer, you can reduce weed densities by applying Round-up to the site when newly-sprouted weeds are two to three inches tall. Wait 7 days after spraying, till the soil very lightly, less than one inch in depth if possible (tilling deeper will only bring up more weed seeds). Plant immediately. If you prefer to avoid using herbicides, wait for a good spring rain after the site is fine-graded. This will stimulate weed seeds to germinate. Five to seven days after the rain, till the soil very lightly, no more than one inch in depth. A field drag works admirably for this job. This will kill the newly germinated weeds before they emerge from the ground. Do the dragging or tilling in mid-morning of a warm sunny day, so that the weed seedlings will be killed by heat. Plant immediately.

Seed Pre-Treatment Options

All Prairie Nursery seed is “dry stratified” prior to shipping to help break seed dormancy. Some wildflower seeds germinate best when seeded in fall in a dormant seeding. The exposure to cold, damp conditions signals to the seed that winter has occurred, and that it will be safe to germinate when the soil warms up in spring. Some wildflowers benefit greatly from a process called “damp stratification,” which mimics the effects of winter on the seed. These procedures are outlined below.

Breaking Seed Dormancy

Dry Stratification

Seed is exposed to cold temperatures for one month or longer. All Prairie Nursery seed is dry stratified, unless purchased prior to mid-January.

Damp Stratification

Seed is mixed with moistened inert material and stored cold for ten days to three months. Many prairie wildflower seeds show improved germination with damp stratification, while prairie grasses generally exhibit little or no increase in germination.

How To Damp Stratify Your Seeds

In a plastic bag or re-sealable container, mix seed with an equal volume of moist (not wet) sawdust or clean builder’s sand (if moisture can be squeezed out of the sawdust or sand, it is too wet). Refrigerate at 34-38 degrees F (do not freeze!). Most flower seeds require three to four weeks of treatment. Legume seeds generally only require ten to fifteen days. Some flowers require two to three months. Note: When planting moist stratified seed, it is important not to let it dry out after planting. The germination process is initiated by damp stratification. For best results, the soil should be kept moist for the first few weeks after planting.

Legume Inoculation

Members of the legume or bean family can benefit from an inoculation with Rhizobium bacterium prior to planting. Your legume seeds have been pre-inoculated with this bacterium. The bacterium works with the plant to form nodules, which are capable of taking nitrogen from the atmosphere and incorporating it into the plant.

Planting Your Seed

When To Plant

Fall - (Sept. 1 up to soil freeze-up)

Advantages

1. Seed over winters as it would in nature and comes up in spring on its own schedule when conditions are right. This breaks most seed dormancies naturally over winter.
2. In general, flower species exhibit increased spring germination with fall seeding.
3. Recommended for droughty, sandy soils because seed germinates earlier in the season, when moisture levels are optimal, and before summer heat.
4. Recommended for clay soils, as clay is easier to work in the fall than in spring, and seeds will germinate earlier in the season. Clay soils often remain wet well into the spring, and by the time they can be safely worked, the heat and drought of summer are often right around the corner. Fall seeding on clay soils encourages earlier germination and better root development prior to the onset of summer.

Disadvantages

1. Warm season grass seed typically exhibits reduced germination.
2. There is no opportunity for early spring weed control by cultivation or herbiciding.
3. Be careful on erosion-prone sites. Plant fall seedings no later than September, with an annual rye or oats nurse crop to help hold the soil over the fall and winter.

Early Spring - (March - April)

Advantages

1. In general, results in better flower germination than planting in late spring.
2. Watering is generally not as critical, as spring rains fulfill this need.
3. Warm season grass seed generally has better germination than in fall.
4. Best option for sandy soils if unable to plant in fall.

Disadvantages

1. Limited opportunity for early, cool season weed control.
2. Not recommended for heavy soils, as it is difficult to work these soils if wet in spring.

Late Spring - (May - June)

Advantages

1. More time for good soil preparation - particularly important on heavy soils.
2. More time for spring weed control prior to seeding.
3. Optimal planting time for warm season grasses.

Disadvantages

1. Increased chance for low moisture conditions later in the season.
2. Reduced germination of some flower species.

Planting Methods

Hand broadcasting seed

1. Start with a freshly-tilled seed bed free of rocks or soil clumps greater than two inches in diameter.
2. Mix all seed (including the nurse crop) with slightly dampened sawdust or vermiculite (approximately two bushel baskets of sawdust per 1000 square feet, or one pickup truck per acre).
3. Divide the seed mixture into two equal groups.
4. Hand broadcast one half of the seed evenly over the entire site.
5. Hand broadcast the second half of the seed over the site, walking perpendicular to the direction walked when seeding the first half. This ensures even seed distribution.
6. Cover the seed lightly, with one-fourth to one-half inch of soil with a rake or drag.
7. Firm seed in the soil by rolling the site with a cultipacker, roller, truck or tractor tires
8. Mulch the designated planting area with approximately 1 inch of weed free straw such as winter wheat or marsh hay. The mulch will help to control erosion on steep slopes and keep sand or clay soils moist during the germination period. If working on steep slopes, cover the mulched area with a photo-degradable plastic mesh with a one half inch openings to allow for un-impeded wildflower seedling development. Secure the mesh with staples placed at one to two foot intervals.

Mechanical Planting of Prairie Seed

Mechanical planting of prairie seed on areas greater than one acre, it is more efficient to plant using a broadcast or a no-till seeder. The broadcast planter spreads the seed over the soil whereas the no-till seeders plant the seed in rows by opening slits in the soil. The broadcast seeder we recommend is the “Brillion” double box agricultural model, typically used to seed alfalfa and grass mixtures but equipped with native grass bristle brushes in the larger front box rather than the standard steel wire agitators. No-till seeders commonly used for prairie plantings include the Truax drill, the Tye wildflower and native grass seeder, and John Deere seeders. On steep slopes, mulching and/or erosion fabric may be necessary to prevent the seed from washing prior to its establishment. For hydro-mulching, only use a cellulose-based mulch and do not use a tackifier. Although grasses are able to penetrate through a tackifier, the wildflower seedlings typically cannot.

Post Planning Maintenance

Year One

Weed control during the first growing season is essential. The perennial prairie seedlings grow slowly, and are easily out-competed by the faster-growing weeds that will inevitably germinate. Seeded areas should be mowed to a height of 6 inches approximately three times during the first growing season. When weeds reach a height of 12-16 inches, the entire planting should be mowed back to 6 inches. As a general rule of thumb, anything that grows taller than 8 inches in the first year is probably a weed. Mowing at 6 inches will cut back taller weeds, while leaving the shorter prairie seedlings unharmed. Use a string trimmer or weed eater on small areas. On larger areas, a flail mower is the best choice. Flail mowers chop up the weeds as they are cut, instead of laying the cut weeds on top of the prairie seedlings. If a flail mower in not available, a rotary mower or sickle bar mower may be used. Be sure to mow before any weeds set seed, to prevent future weed infestation. Do not pull weeds in the first year, as this will disturb or destroy the developing prairie seedlings. At the end of the fall of the first growing season, leave the dead vegetation and stubble standing, to help insulate the seedlings and reduce winter frost heaving.

Year Two

During the spring of the second year, mow the standing residual vegetation to the ground in early spring, and rake off the cuttings. If biennial weeds such as Sweet Clover, Burdock, Wild Parsnip, etc. are a problem, mow again at approximately 12 inches when the majority of biennial weeds are in full flower. Make sure to mow them before they make seed! Expect this second mowing for controlling biennial weeds to occur around mid-June.

Year Three and Beyond

Beginning in the spring of the third year, your prairie can be burned for the first time to maintain its diversity and vigor. Burning in mid-spring helps set back non-native cool season weeds and grasses such as quackgrass, bluegrass, bromegrass, etc. Burning also encourages earlier soil warming in spring, which favors growth of the heat-loving warm season prairie plants. If burning is not possible, your prairie can be mowed as closely to the ground as possible, and then the mowed material raked off to expose the soil and encourage warming.

Timing is very important when burning or mowing your prairie. The goal is to allow undesirable cool season plants to begin active growth prior to burning or mowing, so that they will be harmed in the process. The optimal date for burning or mowing can vary by as much as a month in any given year, due to differences in weather. However, we can use plants as our calendar to ensure optimal timing. The best time to burn or mow most prairies is when the buds of the Sugar Maple tree (Acer saccharum) begin to break open in spring. This usually will occur sometime between April 1 and May 15, depending upon our location and the weather in any given year.

It is recommended that you divide your prairie into two “Management Units.” Burn or mow one half every other year, alternating from year to year so that each half is burned once every two years. This helps prevent invasion by woody plants, as well as cool season weeds. Burning or mowing less frequently than every other year can result in trees and shrubs gaining a foothold in your prairie. Leaving one half unburned or unmowed also leaves butterfly and moth pupae and eggs intact, so that they can re-populate the ecosystem that year. Burning every year is generally not recommended, as it tends to increase the dominance of the warm season prairie grasses and certain prairie flowers. Burning or mowing every other year helps create varying conditions from year to year, maintaining maximum plant and animal diversity.

What To Expect During The First Three Years

Prairie seeds will often germinate over a period of two to three years. Some will appear the first year, while others will come up in the second and even third year after the initial planting. Most perennial prairie flowers and grasses will not begin to flower until their third or fourth full growing season. Patience is a virtue when establishing a prairie! Please follow these directions carefully, and give your prairie time to develop. Although your seeding may appear to be a bit of a weed patch in the first year or two, by the third year numerous flowers and grasses should begin blooming.

Perennial prairie plants devote most of their efforts in the first few years to developing their famous root systems. They will not be readily apparent in the first year, with little visible above-ground growth. However, they are steadily building their “root bank accounts” to sustain them in future years. The deep roots of the prairie flowers and grasses give them long-term staying power that allows them to squeeze out annual and biennial weeds, and to return year after year for decades.

When you plant a Prairie, you’re planting more than just pretty flowers… You’re creating a Plant Community! Put away the lawnmower, sit back, and enjoy your prairie!