Timing first crop alfalfa harvest by calendar date does not usually work well. Spring climates vary from year to year, and fields managed differently also affect spring regrowth. Different varieties, age of stand, fertility, last season’s cutting schedules, fall harvest or not, all influence the rate of regrowth in spring.
Since the first cutting is usually has the highest yield with 35-40 percent of the year’s total crop, it is important that it is the quality forage your operation needs. If the first cutting is taken at a very immature stage it can be difficult to feed because its fiber level is too low for most high producing cows plus it can lower the life of alfalfa stands. Timely cutting permits aftermath growth to begin when when temperature and soil moisture are favorable for plant growth and generally increases total yield per acre.
PEAQ, which stands for predictive equation for alfalfa quality, is a quick and easy method to assess when individual alfalfa fields are ready for harvest based on a forage quality estimate. All you need is a yard stick and Table 1 in ISU Extension publication CROP 3141, which is available from your county ISU Extension office or download at: https://store.extension.iastate.edu/Product/15234