Source: University of Nebraska
By Bruce Anderson, Extension Forage Specialist
Alfalfa seeded this spring is ready, or soon will be ready, to cut. To get the most yield from these new stands, harvest these stands differently than established stands.
With seeding-year alfalfa, stems are spindly, roots are small and shorter, and growth is a little slower.
You can harvest seeding-year alfalfa as early as 40 days after seedlings emerge. It takes plants about 40 days to become able to regrow from the crown after cutting. If plants are cut before this development occurs — maybe to control weeds — at least one set of leaves must remain on the plant for it to regrow.
Although alfalfa seedlings can be harvested 40 days after emerging, it's usually best to wait until around 60 days when plants are at late bud to early bloom stage. Yield will be a little higher and plants will be better able to withstand weather stress with a little extra growth. This extra time also allows roots to penetrate the soil more deeply, helping avoid problems from soil compaction or surface soil dryness.
These first harvest recommendations may be earlier than some folks like to cut. However, after this early cutting the regrowth of seedling alfalfa will become more similar to established alfalfa, giving you the opportunity for two or three cuts the first year. And, it helps control many weeds as well.
One last point — never cut seeding year alfalfa during the four-week period before a killing freeze. Winter injury can be severe due to the smaller root systems.