When the temperature rises above 90° and the humidity is high,
cool-season forages suffer, warns Bruce Anderson, University of
Nebraska Extension forage specialist. Alfalfa and clovers,
bromegrass, orchardgrass, fescues and wheatgrasses grow slowly
in hot weather, their quality drops and they recover slowly
after cutting or grazing, says Anderson. “Warm-season grasses
are just the opposite,” he says. “Millet, sudangrass, sorghums
and our native bluestems, gramas, switchgrass and other warm-
season grasses thrive when the temperature is around 90°. Their
metabolism runs at peak efficiency when it is hot, so they grow
rapidly while maintaining reasonable forage quality and good
root growth.” That assumes that they have adequate moisture, he
adds. Once they dry up, those grasses will overheat just as
cool-season grasses do at lower temperatures. “As you graze or
hay, be aware of the stress weather is putting on your forage,”
Anderson advises. “When it’s too hot, be prepared to allow
plants to recover for a longer