Native Warm Season Grass (NWSG)
Establishment and Management
Native warm season grasses (nwsg) are historically native to Virginia and when managed properly can provide excellent wildlife habitat for many species, including bobwhite quail. Unlike cool season grasses which show active growth during spring and fall, nwsg grow during warmer months of the year. When properly managed for wildlife, these bunch grasses' growth form leaves open space at ground level, providing mobility for small wildlife and opportunity for forbs to grow. Nwsg typically used for wildlife management in Virginia include big bluestem, little blue stem, Indian grass, eastern gamagrass, and switchgrass. These grasses also have benefits as a livestock forage. Broomsage is a nwsg common on Virginia landscapes that has wildlife benefits but little value as livestock forage.
Nwsg communities can be developed by releasing existing native grasses and forbs (wildflowers and beneficial broadleaved plants) from competition with invasive exotics, or by planting nwsg and forbs into a prepared seedbed.
Several excellent publications are available for more detailed information on planting and managing nwsg and are available from Department offices listed at the end of this narrative.
Restoring Remnant Native Plant Communities Suppressed by Invasive Grasses
In many cases, fields may have a strong component of existing nwsg like broomsage undergrown by fescue and other non-native exotics. Treating the stand with herbicide at the proper time of year can release native grasses and forbs from cool-season grass (e.g. fescue) competition. This is the best and least expensive method when creating wildlife habitat is your number 1 goal. It is usually not necessary to plant native warm season grasses unless you are interested in cattle forage, hay or bio-fuels stands.
- Fescue is best controlled in the fall*. Burn, graze, hay or mow the field in late August or September in preparation for spraying herbicide. If mowing is used, remove dead plant material that will block herbicide contact.
- Allow cool season grasses (fescue) to grow 6-10 inches, then spray with 2 quarts glyphosate, 6-7 ounces of nonionic surfactant, and 10 gallons of water per acre, preferably after a killing frost. Spraying at this time will not harm most native grasses and wildflowers since they are already dormant. Cool season grasses must still be green and growing when you spray. Spray on a warm sunny day for best results.
- Monitor the field for undesirable species (fescue, Johnson grass, serecia lespedeza) and spot spray infestations as soon as possible.
- Re-treat in spring if necessary.
- Read and follow all herbicide and adjuvant label directions.
* There are special circumstances that may require spring control. Detailed instructions can be found in "A Landowner's Guide to Native Warm Season Grasses in the Mid-South" (PDF) University of Tennessee Extension Publication 1746.
Planting Native Warm Season Grasses
Planting native warm season grasses requires care and patience. There are several critical factors to be aware of to achieve a successful nwsg stand:
- Place seed no deeper than ¼ inch. Some seed should be evident on the soil surface.
- Ensure that enough vegetation is removed to get good seed/soil contact.
- Weed control is imperative. Existing sod must be killed before planting. Weeds that emerge soon after planting must be controlled to avoid competition with nwsg seedlings.
- Seek high quality seed. Purchase seed with high germination rates and calculate the amount of pure live seed in the lot before planting.
- Be patient! It can take up to two years before a nwsg stand shows its full potential*.
* There are new technologies being used by commercial native warm season grass establishment companies that have taken nwsg planting to a higher level. These techniques include modified equipment not available to the general public except through commercial contracting. The above method can and has worked for folks interested in establishing forages. It works very well from a wildlife perspective. However, if your plan is to grow large volumes of nwsg for cattle forage, or bio-fuels and you do not have 2 or 3 years to invest in establishment, you should consider contracting with a commercial nwsg establisher.
Pure Live Seed: It is important to calculate nwsg planting rates knowing the seed lot's percentage of pure live seed (pls). This can be calculated from the information on the seed tag. As an example, assume a landowner is a beef producer and wants to plant a forage mixture of big bluestem, Indian grass, and little blue stem at a rate of about 9 lbs of pls/acre. The mixture might include 3.5 pounds of big blue stem, 3.5 pounds of Indian grass, and 3.0 pounds of little blue stem per acre. To calculate the amount of big blue stem needed in the planting mix, consider both the percentage of pure seed and the total germination rate. In this example, assume the big blue stem seed is 70% pure and has a total germination rate of 80%. To calculate percentage of pls multiply the percent pure seed by the total germination rate, then divide the result by 100. In this case, 70 x 80 = 560; 560/100 = 56 % pls.
To calculate the actual amount of big blue stem seed to include in the mix, divide the desired planting rate ( 3.5 pounds per acre) by the percent pls (56) and multiply by 100. The result, 6.25 lbs., is the actual amount (the "bulk seed rate") of big blue stem seed material from the seed bag you will need to plant per acre. The same calculations would be made for the Indian grass and little blue stem in the mixture.
Seed Dormancy: Switchgrass and eastern gamagrass seed often have high dormancy rates. If germination rates are above 50%, go ahead with planting. If less than 50%, you can improve germination by "cold-stratifying" or "wet-chilling" the seed to break dormancy. For switchgrass, soak seed in a mesh sack overnight and allow it to drip dry the next morning. Store the seed at about 40-45 degrees F for 30 days. Stir the seed every 3 days to provide oxygen to all of the seed. After the 30 day wet-chill, air dry seed with a fan until the seed flows freely. Plant immediately. Eastern gamagrass requires a 6 week wet-chill and it is more convenient to purchase cold-stratified seed directly from a dealer. If you are dealing with large volumes of seed that are impractical to wet chill and dry, an alternative is to buy the seed during fall and keep frozen through winter with no wet chill. Simply place seed bags in a large freezer unit, off the ground where air can circulate, and where it will stay dry. A locker used to freeze and store meat is ideal.
Planting Dates: Nwsg are planted from May 1 through June 30 in Virginia. In the Coastal Plain this date can be extended forward to about April 20. In the Piedmont and mountains the planting date can be extended through the first week of July if moisture is adequate. If forbs are included in the mix seeding should be completed in May. Some forbs used in nwsg plantings are sensitive to Plateau herbicide (including Kobe or Korean lespedeza, sunflowers, coreopsis and others) and should be planted later if Plateau is used. To establish forbs at a later date disc (1 disc wide) scattered strips through the established nwsg, broadcast forb seed, then roll/cultipack the seed. Partridge pea and black-eyed Susan are tolerant to Plateau and can be added directly to the nwsg mix.
Establishing NWSG and Forbs in Cropland
Existing cropland can be converted to a nwsg and forb community using the following steps. This procedure assumes that there is little weed competition within the field, and that the weeds are annuals. If fescue or other persistent weeds are present use the procedures outlined for converting a fescue field.
- Till the field to create a seedbed suitable for an agricultural crop.
- Cultipack to firm and smooth the soil.
- Apply 6-8 oz. Plateau herbicide per acre on the planting day. (An alternative to using Plateau is to use no herbicide. However, if no herbicide is used expect increased weed growth and slower grass establishment. Regular mowing above the nwsg seedling height will be required).
- Seed with a nwsg no-till drill (available at VDGIF locations noted below) OR broadcast seed. A carrier such as cracked corn, granular lime, or fertilizer is needed to distribute fluffy seed. New varieties of "de-burred" big bluestem and Indian grass seed are available from many companies, but must be asked for specifically and are slightly more expensive. The de-burred seed will work much better for broadcast seeding. (Roundstone Seed Company 270-531-2353, or Star Seed, Inc. 785-346-5447). Note: planting eastern gamagrass requires an attachment suitable for corn since the seeds are about the same size.
- If seed is broadcast, cultipack the field to ensure adequate seed/soil contact.
Establishing NWSG and Forbs in Fescue, Other Monocultures, or Weedy Fields
The following procedure works to establish a native grass community in fescue or other non-native cool season grass fields. These fields may also contain a suite of other non-native exotic species like serecia lespedeza. It is critical that fescue or other vegetation be controlled before attempting to establish nwsg.
- Burn tall fescue in late winter for a spring kill or late summer for a fall kill. Substitute heavy grazing or haying to remove as much vegetation as possible if burning is not an option.
- Allow 6-8 inches of regrowth, then spray while plants are actively growing.
- If implementing a spring fescue kill, spray the field, then wait two weeks and respray or spot spray if there is still green fescue. If implementing a fall kill, spray, then burn in late winter to reduce surface debris. Respray or spot spray in spring if needed.
Use 2 qts per acre glyphosate (Roundup) plus 6 oz. nonionic surfactant plus ammonium sulfate at 17 pounds per 100 gal. of spray. Use a 10-25 gallon per acre spray rate.
Use 12 oz. per acre Plateau plus 2 pints of methylated seed oil per acre.
- Seed with a nwsg no-till drill (available at VDGIF locations noted below) OR broadcast seed if a drill is not available. Use a carrier such as cracked corn, granular lime, or fertilizer to distribute the fluffy seed).
- If seed is broadcast, cultipack the field to ensure adequate seed/soil contact.
Seeding Mixture & Rates Table*
|Seeding mixture (lbs PLS per acre)||Objectives and Considerations|
|Wildlife - tall grass mixture
1.5 lb. big bluestem
1.5 lb. Indian grass
1.0 lb. little bluestem
0.5 lb. switchgrass
1.0 lb. native forbs
|Wildlife - short grass mixture
3.0 lb little bluestem
1.0 lb sideoats grama
0.5 lb Indian grass
1.0 lb native forbs
3.5 lb big bluestem
3.5 lb Indian grass
3.0 lb little bluestem
|Hayed after primary nesting season
Imazipac (Plateau) can be used for competition control)
8-10 lb switchgrass
|Wet-chill seed before planting
Seed with conventional equipment
10-12 lb eastern gamagrass
|Buy cold-stratified seed
Plant with corn planter with rows 12-24 inches apart
*Table information taken from Harper, Craig A., G.E. Bates, M.J. Gudlin, M.P. Hansbrough. 2004. "A Landowner's Guide to Native Warm Season Grasses in the Mid-South" (PDF). University of Tennessee Extension. 25pp.
Managing the Emerging NWSG Stand
Once nwsg seedlings emerge monitor the site for significant weed competition. Remember, though, that if your primary goal is wildlife habitat, a mixture of native grasses and broadleaved weeds is best. Your goal is a stand consisting of 30 - 50% native grasses, 5% to 10% shrubby, woody cover like plum, sumac, or blackberry thickets, and 30% - 40% broad leaved weeds, such as rag weed, partridge pea, Korean lespedeza, tick seed sunflower, black eyed Susan, and beggarweed. Weed management when establishing wildlife cover may only be necessary in extreme cases. For cattle, hay or bio-fuels stands, weed competition can usually be managed by mowing on an as-needed basis when weeds are about 12 inches tall. Set the mower height above the nwsg seedlings (minimum 8 inches high) to avoid damage to the grass. Do not graze or hay the emerging stand during the establishment year while the seedlings are developing root mass. If the nwsg stand is being used for haying or grazing wait until after mid-June a year after planting to avoid the peak periods of nesting and fawning.
NWSG and Forb Stand Management
Once the nwsg stand has become established it must be managed to maintain the field in early successional habitat. Begin management the third growing season after planting to allow deep root formation.
Treat about 1/3 of the acreage (1/2 if 4 acres or less) each year in a continuing rotation. This schedule benefits wildlife by creating more diversity within the grass/forb community. Burning is the best management practice for maintaining nwsg stands. Other options include disking or haying, or some combination of techniques.
Prescribed burning of nwsg stands: Prescribed fire reduces buildup up of dead vegetation, increases nutrient availability and frees herbaceous plants from grass competition. The season in which a prescribed burn is conducted will influence the vegetation composition after the burn. Fields are typically burned in late winter (February through March) though the burning season can extend into early April. Late winter/early spring burns typically favor nwsg over forbs. Use of fire in late summer/early fall helps set back grass plantings that may have become rather dense and stimulates forb production. Before conducting a prescribed fire it is advisable you complete a certified prescribed burning course through the Virginia Department of Forestry or work with an experienced prescribed burner. A list of prescribed burning contractors can be obtained through your VDGIF biologist.
Disking nwsg stands for wildlife: Strip disking is an alternative to using prescribed fire to manage nwsg stands, or can used be used after controlled burning to thin a stand that has become too thick for wildlife. Strip disk a different third of a field each year by disking an area 20-30 feet wide, move over 50-60 feet, then disk another 20-30 feet. Repeat across the field. Disk on the contour to prevent erosion. A sturdy, heavy disk will be required to adequately break up thick, well rooted warm season grasses. If you have specific native forbs that you want to add to your field mixture, broadcast seed into the disked areas. Purple cone flower, butterfly weed, rag weed, round headed bush clover and partridge pea are some of the forbs you may want to consider. Disking at different times of the year will yield different results regarding forb composition. You can experiment with the timing to learn how the seed bank responds to disking at various times of year. Though mowing is not a recommended practice for managing nwsg, you may need to mow over strips before disking is possible.
Haying nwsg stands for wildlife: Haying a nwsg stand will keep the field in an early successional stage, but has less benefit for wildlife than burning or disking. When haying primarily as a wildlife management tool, hay after July 15 when the plants have reached a height of 30 inches to allow completion of most nesting and do not cut lower than about 8 inches to maintain a healthy stand.
Grazing nwsg stands: NWSG are actively growing during summer and provide high quality forage at this time. Big bluestem, Indian grass, switchgrass and eastern gamagrass can be grazed when they are over 15 inches tall, however, to maintain a healthy stand nwsg should not be grazed below 12 inches.
Controlling invasive exotics: NWSG stands should be monitored for invasive exotic plants. It is worth becoming familiar with identification of non-native species like fescue, serecia lespedeza, spotted knapweed, and non-native thistles so that problems can be addressed before they spread! Spot spraying or broadcast spraying these and other problem invasives will likely be a necessary management practice. Always read and follow herbicide label directions and precautions.