Plan for delayed grazing season

A combination of fall drought and a delayed spring due to colder than normal temperatures are expected to cause significant delays in grass development and growth this spring.

Air temperature in the spring is the main environmental factor that determines the rate of grass development.

Miranda Meehan, North Dakota State University Extension livestock environmental stewardship specialist, explains that each leaf produced on a stem requires a specific amount of accumulated heat or heat units. The temperature when plants initiate development, the base temperature, is 32 degrees Fahrenheit for cool-season grasses and 40 degrees Fahrenheit for warm-season grasses. The temperature or heat units that a plant needs to accumulate to produce a leaf can be expressed as growing degree days (GDD).

Perennial grasses start to accumulate growing degree days the first day after March 15 that the average daily air temperature exceeds 32 degrees for five consecutive days. The number of GDD needed to reach grazing readiness varies between grass species from 443 GDD for crested wheatgrass to over 1,000 GDD for most native species.

On average, cool-season grasses begin accumulating GDD on March 24 near Bismarck and March 30 near Jamestown. This spring, both locations did not start accumulating GDD until April 13. In addition to being delayed, GDD are accumulating slowly due to cooler than average temperatures, which are expected to remain below average in May.

Grazing readiness is the developmental stage where the plant is able to recover from the stress of grazing the previous year and produce sufficient levels of water-soluble carbohydrates (food) to replenish the roots. Grazing readiness for most domesticated pastures, such as crested wheatgrass and brome grass, is at the 3-leaf stage; whereas, grazing readiness for most native range grasses is the 3 1/2-leaf stage.

All cool-season grasses, which are the dominant grasses in North Dakota, initiate growth from a tiller that was established the previous growing season. However, drought stress during the fall of 2022 resulted in poor tiller development. Grazing management in the fall may have caused tillers to die. Poor tiller development and tiller death last fall are expected to delay development an additional one to two weeks this spring.

Pastures that have had tiller loss must be given adequate time to recover. Grazing too early in the spring can result in decreased total forage production for the entire grazing season.

“You may sacrifice 45% to 60% of forage production for the year by grazing too early,” says Kevin Sedivec, NDSU Extension rangeland management specialist and interim director of