In general, full season hybrids at any location will yield most. Length of season differs across Nebraska. In the fall, the average date of first frost varies from Sept. 15 in the northwest to Oct. 15 in the southeast. Growing degree days vary from about 2,100 in Kimball, Scotts Bluff and Box Butte counties to 3,300 in Webster, Nuckolls, Thayer, Jefferson, Gage and Pawnee. Based on Growing Degree Days .
Hybrids react differently to latitude, location, altitude and other factors.
Temperature and moisture conditions through the season can modify rates of development. Thus, there is no precise measure of maturity for any hybrid in terms of days from planting to harvest. When carefully rated at one location, such ratings do show relative maturity. In yield tests, moisture content at harvest is frequently given as a measure of relative maturity since all hybrids in such tests are harvested on the same date. The harvest day for the tests should be soon enough after the earliest hybrids mature so that a meaningful range of moisture differences exists between the early and late hybrids.