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Grazing Factsheets -Establishment\Renovation

Grazing Factsheets


Establishing Warm-Season Grasses
Frost Seeding and Species Suitability
Alfalfa Autotoxicity
Weed Control
Seed Quality


Outline of State of Illinois with Grass
Establishing Warm Season Grasses



Care and attention to detail must be considered when establishing warm-season grasses. Farmers and ranchers familiar with planting techniques for cool-season grasses may need to change some of their management methods to ensure that their warm-season grasses develop into thrifty, profitable forage crops.

When establishing warm-season grasses, consider:

  • Soil testing
  • Seed quality
  • Seeding rates
  • Seedbed preparation
  • Planting techniques
  • Evaluation of newly-seeded fields
  • Weed control and fertilization

Some steps necessary to ensure success with warm-season grasses.

Soil Testing

Each field should have an independent soil test. Generalizations about soil types within a field and characteristics cannot be made because of soil variances within relatively small areas. The tests will show the pH of the soil and reveal any nutrient deficiencies.

Soil pH should be above 5.5 in order to establish warm-season grasses. If soil tests reveal a need, lime, which increases the alkalinity of soil, should be added to the soil at least five months before planting. Deficiencies of phosphate or potash can be corrected during seedbed preparation. Nitrogen should not be applied during early establishment of warm-season grasses since nitrogen will promote competition from undesirable plants.

Seed Quality

Quality of warm-season grass seed is extremely important and quite variable. Warm-season grass seed is sold on a “pure live seed” (PLS) basis. PLS refers to the percentage of seed that is capable of germinating. Information is usually included on a tag attached to the seed bag. For example, a 50-pound bag of bulk grass seed might contain 40-pounds of pure live seed and 10 pounds of dead seed or trash. The PLS percentage of the seed would be 80 percent. If you purchase untested warm-season grass seed, there is no way of knowing how much pure live seed you are purchasing. In addition, weed seeds could be included in your purchase.

Seeding Rates

Seeding rates for warm-season grasses are dependent on the method of planting as well as the intended use of the grass. Seeding rates also depend on the type of seed planted. Increasing the seeding rate may compensate for poor seed placement by inadequate seeding equipment or poor seedbed preparation.

Depending on the species, warm-season grasses, are seeded from mid-April to mid-June in northern Illinois. In southern Illinois, planting can begin as early as April 1. When there is a choice, the earlier dates are recommended.

Seedbed Preparation

Minimum seedbed preparation usually includes chisel plow, disk, harrow, and cultipack in order to firm up a seedbed. To check for adequate firmness, walk across the prepared seedbed. Your footprints should only be as deep as the sole of your shoe. If the field contains cool-season grass, you may need to chemically kill the sod before preparing the seedbed since some cool-season grasses may survive tillage. If the sod has been chemically treated, you have the option of preparing a clean-tilled seedbed or no-tilling into the residues. For clean-tilled seedbeds seed can be broadcast on to a firmly packed seedbed but drilling is the preferred method of seeding. Take extra care in treating existing sod with herbicides if no-till is the chosen method of seeding and use a drill that will place the seed at the proper depth and offer good soil contact.

Planting Techniques

When planting warm-season grass seed, two things are important - a firm seedbed and proper seed depth. Plant shallow. The ideal planting depth is one-quarter to one-half inch. Many conventional grain drills place the seed too deep. Planting deeper than one-half inch usually results in failure. De-bearded seed is recommended, and more costly, but specialized planters are needed if bearded seed is used.

Evaluation of Newly - Seeded Areas

An important step that is often overlooked is proper evaluation of a new seeding. Warm-season grasses require a soil temperature of 55oF or 13oC or above for germination. With sufficient moisture and soil temperatures new seedlings should emerge in 10-20 days. Problems arise because other grasses and weeds also emerge. People unfamiliar with grass seedlings often assume a planting has failed because of improper identification; especially true when seeds are broadcast because rows are not apparent. Digging up a few new seedlings and looking at the attached seed can help. In addition, consulting a native grass specialist with the Illinois Department of Natural Resources, Natural Heritage, Natural Resources Conservation Service or the University of Illinois Extension may prove worthwhile.

When proper steps are taken, warm-season grasses establish themselves quite rapidly. They generally establish themselves more slowly than cool-season grasses. But, while the aboveground growth of newly planted, warm-season grasses may seem slow, native warm-season grasses are busy developing extensive root systems.

If seedling density does not appear to be high with your warm-season grasses, don’t panic. An adequate, mature stand of native warm-season grass might have only one plant per square foot. A stand with only one plant per square yard may be salvaged with good management. Individual plants can become quite large, and may fill in poor stands by self-seeding or spreading vegetatively.

Weed Control and Fertilization

Since native warm-season grass seedlings grow slowly at first, competition from other grasses and broad-leaf weeds can be severe. Weed control is a must. Mowing or spraying can control weeds. Mowing weeds is effective when they reach a height of 18 inches. Don’t mow lower than four to six inches or native grass seedlings could be damaged. Up to three mowings the first year may be needed, but remember to always mow above new seedlings. In addition, don’t mow after August 1 when plants are storing carbohydrates for the winter. For chemical control check with Natural Resources Conservation Service, the Illinois Department of Agriculture, or the University of Illinois Extension Service, and pay close attention to label instructions. Do not graze a new planting the first winter because grazing can pull new seedlings loose. New plantings that exhibit a dense stand of grass with few weeds can be fertilized in May or early June of the second year or when grasses are about eight inches tall. In general, 50 pounds of actual nitrogen per acre is recommended.


Warm-season grass seedings offer few opportunities the first year for hay and grass producers. Don’t be over anxious. Plantings may not develop their full potential until the third growing season. Graze lightly, even during the second growing season. Correct timing of haying and grazing along with proper cutting and grazing heights will ensure maximum production of native warm-season grasses.

Where to Get Help

For more information about warm-season grasses, contact your local office of the Natural Resources Conservation Service, listed in the telephone directory under “U.S. Government,” or the University of Illinois Extension.

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Outline of State of Illinois with Grass
Frost Seeding


Frost seeding (sometimes called overseeding or surface seeding) is the broadcast, surface placement of seed in late winter, early spring. Ideally, the soil should still be frozen. This method is dependent upon the freezing and thawing cycles of soil, plus late snowfall or early spring rain, and perhaps livestock traffic to provide seed-to-soil contact/coverage. One should avoid frost seeding on heavy snow. Probability of success will be lessened in years with dry springs and on sandy soils.  


Interest in this old technique has increased with efforts to improve pasture productivity and quality. Frost seeding is one of the most cost effective and energy efficient seeding methods. Since it works well on slopes, frost seeding reduces soil erosion that could occur if the soil was tilled. 


Cyclone-type spreaders that mount onto ATV’s or tractor 3-point hitches are commonly used in frost seeding. One must determine the effective seeding width for each type of seed or mixture.

Better stands are obtained when frost seeding into a bunch grass or into thin sods of a sod forming grass. Pastures to be frost seeded need to be grazed heavily or closely clipped in the fall to reduce plant competition.

Frost seeded pastures need to be grazed regularly in the spring and summer to allow sunlight to penetrate the plant canopy. But, livestock should not be allowed to closely graze the new seedlings until they are established.

Since there may not be uniform seed germination and emergence, frost seeding is designed for pastures and not for establishing hay fields.

Species to Seed

Species that germinate rapidly are best for frost seeding. Medium red clover is the easiest legume to frost seed due to its good seedling vigor, shade and cold tolerance. A second option would be ladino clover. Even though slower to establish, lespedeza may be considered in southern Illinois. Frost seeded legumes need to be properly inoculated, the soil pH must be in the proper range, and soil drainage must fit the species.

Most cool-season grasses do not establish from frost seeding as well as legumes. However, farmer experience and university data indicate that ryegrass (forage type) and orchardgrass can be successfully frost seeded. 

Seed Rates

Red clover can be seeded at 4 to 6 pounds per acre and ladino clover at 2 to 3 pounds per acre. If mixed, seed 3 to 4 pounds of red clover plus 1 to 2 pounds of ladino clover per acre. Lespedeza can be seeded at 8 to 10 pounds per acre.

Ryegrass (forage type) can be seeded at 8 to 10 pounds per acre and orchardgrass at 3 to 4 pounds per acre. 


With proper management and cooperation from Mother Nature, frost seeding is an economical, effective way to improve the quality and quantity of pastures. 

Where to Get Help

For more information about forage testing contact your local office of the USDA Natural Resources Conservation Service, listed in the telephone Directory under “U.S. Government,” or the University of Illinois Extension.

USDA is an equal opportunity provider, employer, and lender.
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Outline of State of Illinois with Grass
Alfalfa Autotoxicity

What is it?

For this topic, knowing the definition of two terms is important. Allelopathy is the effect of one plant on another as a result of the plant producing chemical compound(s). Autotoxicity is a form of allelopathy where a plant species releases chemical compound(s) that inhibit germination and growth of the same plant species.

Alfalfa contains water-soluble inhibitory substances that are autotoxic.

Where are Autotoxic Substances Located?

The greatest concentration is found in the alfalfa leaves and seed.

What Does Autotoxicity Cause?

Autotoxicity causes a negative effect on seed germination and seedling growth, especially reducing the growth of the radicle or the young developing taproot. Reduced seedling growth is seen as stunting in the field. This effect may be apparent for at least 3 years.

The autotoxic substance(s) can move with water, and thus will leach out of the root zone faster in a sandy soil than in a clay soil. Amount of rainfall is also an influencing factor.

What’s the Impact of Autotoxicity?

Research has shown a “zone of influence” where older alfalfa plants release the autotoxic substance(s) that affects new seedlings in a “wagon wheel” pattern radiating outward from the older plants. New plants established within 8 inches of the old plant rarely survive and yield 30% of maximum, new plants established 8 to 16 inches away from the old plant yield 75% of maximum, and new plants 16 to 24 inches away from the old plant achieve maximum growth and yield.

When to Interseed with Alfalfa?

Using this “zone of influence”, one could successfully interseed with a plant density of 0.2 old plants per square foot. At 0.4 old plants per square foot new seedlings can be established but will be low yielding. If there are greater than 1.3 old plants per square foot reseeding will not be successful due to “zone overlap.”

The practice of interseeding alfalfa into alfalfa to thicken a stand usually fails due to this “zone of influence” and competition from existing plants.

Reseeding Guideline

If the alfalfa stand is greater than a year of age, the Illinois recommendation would be to plant a grass crop (corn is best) for one year and the following year reestablish alfalfa. If the alfalfa stand is less than a year of age, one could reestablish or reseed alfalfa.

Other Factors To Consider

Research has shown that high rates of fungicide on alfalfa seed interseeded into old alfalfa stands had no impact on emergence and establishment, and stands were not successfully interseeded. Grazing-tolerant varieties produce autotoxicity.

Studies suggest that there may be genetic differences in varieties to the autotoxic substance(s). Alfalfa seed companies are exploring the development of genetic resistance.

Options to Thicken a Stand

Thickening old stands of alfalfa can be done with red clover (medium type) and/or good quality cool-season grasses.

Optimum Alfalfa Plant Density

Optimum stand of alfalfa grown for hay is 55 stems per square foot and if less than 39 stems per square consider replacing the stand. Excellent gains on pasture have been obtained with alfalfa plant density less than the optimum for hay production.

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Outline of State of Illinois with Grass
Weed Control


In pastures, woody and herbaceous weeds can become troublesome. A weed is defined as a plant out of place and in pastures they may be toxic or unpalatable, compete for light, moisture, and nutrients, and take up space needed for desirable species. However, some weeds at certain growth stages can be nutritious.

Basic Principle and Life Cycles

Successful weed management begins with correct identification. Weeds can be classified as annual (completing their life cycle within one year), biennial (lives for two years), or perennial (lives for more than two years). There are winter annuals and summer annuals. Annuals and biennials reproduce only from seed, and perennials reproduce from seed and vegetative reproductive parts (rhizomes, stolons, etc.). Plants of all life cycles are easiest to control when they are seedlings. Annuals and biennials are much easier to control than are perennials.

Control Practices

Serious weed control problems should be taken care of before implementing or changing a grazing program. Pasture weed control includes cultural, mechanical, chemical, and biological management practices.

Cultural management consists of maintaining a dense, uniform, and vigorously growing sword. Good grazing management (leaving the appropriate stubble height and providing pasture rest periods) and maintaining optimal soil fertility are important weed control strategies. Continuous grazing at high stocking rates will weaken the stand and cause weed problems to increase rapidly.

Mechanical management includes mowing or clipping and hand digging. If this practice is repeated during the growing season, annual and biennial weeds can be reduced since the food reserves in the roots are depleted and seed production is reduced. Some graziers clip pastures after every grazing period to allow uniform regrowth and to weaken weed species. Mowing is less successful in controlling perennial weeds.

Chemical management starts with reading and following label directions. Weeds vary in their susceptibility to herbicides and the timing of application may affect the degree of control.

Annuals and biennials are most easily controlled when small. A fall or early spring herbicide application works best if biennials or winter annuals are the main problem. Apply translocated herbicides to control established perennials when these weeds are in the bud-to-bloom stage.

Herbicides can be broadcast or spot applied. Be sure to follow the grazing restrictions and reentry periods. Be aware of the rain-fast period for foliar applied herbicides. Remember that many pasture herbicides will damage legumes as well as control broadleaf weeds.

Details on herbicide options for pasture weed control are found in the current Illinois Agricultural Pest Management Handbook, available at University of Illinois Extension offices.

Biological management is the use of living organisms to control pests (weeds in this case). One example is the use of the musk thistle weevil to control the musk thistle. The weevil will not eradicate musk thistle, but can certainly reduce their numbers. This strategy has been used especially in hilly, rough terrain where mowing is not feasible.


Weeds can reduce the vigor, yield and quality of pastures. The first step in weed management is proper identification. No one single management practice (cultural, mechanical, chemical, and biological) will result in weed free pastures. The grazier must adopt an integrated approach utilizing each of the above mentioned management practices.

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Outline of State of Illinois with Grass
Seed Quality

Pure Live Seed Calculations

IAll seed shall be of high quality and comply with Illinois Seed and Weed Laws. Pure Live Seed (PLS) is an indication of seed quality: however, it is rarely shown on the seed tag. All USDA-Natural Resource Conservation Service (NRCS) and U of I Agronomy Handbook seeding recommendations are provided on a Pure Live Seed basis. To assist in determining the calculations for this we are providing the formula and an example to assist in calculating the proper amount of seed to be sown per acre.

Seed quality shall not drop below 70% Pure Live Seed (PLS) for bromegrass and 80% for other cool season grasses and legume species.

Percent PLS is calculated by multiplying the purity of the bulk seed lot by the percent germination plus percent dormant seed rates, then dividing that sum by 100. If planting a bag of seed that is 94% pure and a germination rate of 80%, with 5% dormant seed then you would calculate it this way:

PLS = [(%germination + % dormant seed) X % purity] divided by 100.

(80% germination + 5% dormant seed) X 94% purity =79.9 % Pure Live Seed

If planting 12 pounds per acre PLS and the seed used had a PLS of 79.9% then you would need to purchase 15 pounds of seed per acre to have the proper amount to plant.

12 divided by 79.9 X 100 = 15.01#/acre

In other words, you would have to plant 15 pounds of material from the seed bag of that species in order to plant 12 pounds of PLS per acre.

Minimum germination percent for warm season grasses shall be as follows:
Switchgrass – 75%
Indiangrass – 60%
Big Bluestem – 60%
Eastern Gamagrass – 50%

Germination tests should be no older than 6 months on warm season grasses.
Farmer-produced seed will be tested for germination prior to seeding.


References: USDA-NRCS Field Office Tech Guide Pasture and Hayland Planting 512, U of I Agronomy Handbook Chapter 8.

Where to Get Help

For more information about contact the local office of the USDA-Natural Resources Conservation Service or University of Illinois Extension.

Prepared by
Roger Staff, NRCS Grazing Specialist

USDA is an equal opportunity provider, employer, and lender.
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