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Topics : Species and Forage Variety Trials : Species Fact Sheets : Warm-Season Grasses

Species: Warm-Season Grasses

Additional warm-season grasses information via the Forage Information System (FIS)


Big Bluestem & Switchgrass Establishment

Warm-season grasses grow best on deep, well-drained soils. However, if they must be seeded in a poorly drained sight, switchgrass is more tolerant of poorly drained soils than big bluestem. Both switchgrass and big bluestem have been established on low fertility and low pH (4.6) soils without adding lime or fertilizer. However, warm-season grasses establish faster on low fertility soils when fertilizer is applied.

Warm-season grasses should be seeded alone either on a conventional, tilled seedbed or no-tilled into grain stubble between mid-April and mid-May. Later seedings are slower to establish, yield less, and have more weed infestation the year after seeding. Successful spring seedings have also been made by no-tilling warm- season grasses into a small grain crop that has been killed with a herbicide. Good seed soil contact is very important for establishment of warm- season grasses, therefore, a tilled seedbed should be free of weeds, fine-textured, and firm. Plowing, disking, harrowing, and cultipacking generally are required. Band seed to a depth of 1/2 inch with a drill equipped with press wheels. If broadcast seeded or drilled without press wheels, rolling or cultipacking after seeding is necessary to assure a good firm seedbed.

Switchgrass seed is hard and smooth and can be handled without special drills. Big bluestem seed is chaffy and will not flow well unless it has been debearded, a process which removes the chaff and hair from this seed. Use debearded big bluestem seed to avoid seeding problems. Switchgrass and bluestem seeding rates of 8-10 and 10-12 lb per acre, respectively, of pure live seed is recommended for vigorous stand establishment. Pure live seed is easily calculated as (% germination x % pure seed)/100. Most attempts to establish and manage a switchgrass or big bluestem mixture with either alfalfa or red clover have not been successful. The legume dominates the mixture within two years. However, resent research has shown that legumes can be maintained in a stand with warm-season grasses if the legume and grass are seeded in alternate rows and harvested in the spring based on the warm- season grass.

Under ideal conditions, warm-season grasses can establish and reach a height of 5 ft in the year of establishment. However, it generally takes two years to reach their maximum growth potential because of slow germination and seedling growth. Stands which appear poor at the end of the first year usually develop into good stands the second year. It is important to evaluate the stands at the end of the seeding year. If there are at least 1 to 3 seedlings per square foot in September, the stand is adequate.

Weeds can be very detrimental in the seeding year because of the slow growth of warm season grass seedlings. Because warm-season grass seedlings are poor competitors with weeds, sites with severe perennial weed problems such as quackgrass or broadleaf weeds should be avoided. Following recommended establishment procedures can help reduce weed pressures. If plowing and disking is done early, weeds can be allowed to germinate and then eliminated with a contact herbicide or a light harrowing or disking before seeding. Mowing weeds to reduce shading may be beneficial and should be done at a height above the grass seedlings and not later than early August. Broadleaf weeds can be controlled with herbicides when the grasses are seedlings. Refer to the Pennsylvania Agronomy Guide for current herbicide recommendations and label restrictions.