Q: We have irrigated pasture mix consisting of orchard grass, clover, alfalfa,smooth brome, and intermediate wheat grass. My question is we are seeing a rapid green up and I am concerned about possible frost damage if it were to get cold. Can I graze that with a large number of yearlings quickly and get off without doing more damage than the frost would?
A: The effects of a light frost on the cool-season grasses in your irrigated pasture mix are usually very minimal. Grant it, that if the freezing temperatures were quite low; such as the lower to mid 20's; then one would expect some damage to the upper leaves, but they would recover fairly quickly. Freezing temperatures that we could get in mid or late May have a greater effect on warm-season native grasses as far as setting back their growth. For you irrigated cool-season mix, I would suggest holding off on any grazing until it averages about 6 to 8 inches tall. If this is an established stand, it usually reaches this height in late April to early May in your area. It could be earlier depending on spring conditions. The grasses will grow very rapidly in during May and the initial grazing should be watched closely because if they are grazed too heavily early, this will reduce some of the production potential in May. If this is a new stand (seeded last fall); it is suggested to delay the initial grazing until about the third week of May to allow those grasses to further develop their root systems.
Source: Dr. Jerry Volesky, Associate Professor of Agronomy West Central Research & Extension Center, University of Nebraska