By Margaret Smith, PhD
Forage Agronomist

Many alfalfa fields have already been cut this season, or farmers are planning to make their first-cut harvest soon. Many alfalfa fields in our region had a degree of winterkill, and some growers were fortunate to have conditions earlier this spring to interseed into these stands, but many were not.

Increasing Forage Yield This Year

The best options now are fewer than in the early spring. Warm season grasses, interseeded into alfalfa stands, can give great forage yields from August 1 into September, and may also provide grazing into October. (See Summer Seeding Options below).

The best option right now to supplement your alfalfa hay is teff. This warm-season grass can be hayed on the same schedule as the alfalfa. The firm ground under the established alfalfa is perfect for a teff seedbed. Use a no-till drill with good firming wheels. Other options for mulit-cut hay include sudangrass and Japanese millet. Both of these dry somewhat more slowly than teff. Foxtail millet (German or Siberian) and Proso millet can also be hayed, but will provide only one cutting.

Other warm-season grasses: forage sorghum, sorghum-sudangrass, and pearl millet may be planted, but are better suited to use in baleage or silage, due to their thicker stems that dry more slowly.

Any of these other warm-season options, in addition to teff, can be no-tilled into a thin alfalfa stand. These other warm-season species grow taller than teff and will shade the alfalfa later in the summer. If a no-till drill isn’t available, the alfalfa field may also be tilled, and warm-season forage crop then seeded. This may make harvesting easier than with a mixed alfalfa/warm-season grass stand.

Establishing New Alfalfa or Alfalfa/Grass Stands

Still short on established alfalfa for 2020? With very depleted stands – fewer than 3 plants/ft2 and/or fewer than 39 stems/ft2 – it may be time to completely replace the stand. We’ve already passed the optimal spring planting window for cool-season hay species, but there are a couple of options to consider. Optimum results with reseeding into the same field are with a full year between hay seedings.

You may plant alfalfa into the same field that has your thin stand next year IF you terminate that stand NOW. You can use either herbicides or tillage, but tilling any remain alfalfa residues, followed by warm summer temperatures, adequate moisture and growing grasses allow time and the environment for microbial activity which breaks down alfalfa’s autotoxic compounds. As soon as possible after termination, plant a warm-season grass in that field.

Fall seed alfalfa and alfalfa grass mixes can be established successfully in mid-August in southern Minnesota. Seed in early August in central Minnesota and Wisconsin and as late as September 1 in southern Iowa. The objective is to get seeding done six weeks before your average date of the first killing frost. A nice advantage to establishment at this time is that you don’t need to use a companion crop, or herbicide to aid in establishment. Any annual weeds that do germinate in this establishment period will winterkill. Any prevented panting acres would be available to establish a new alfalfa stand this August. You may not harvest until after November 1, or wait to harvest in spring of 2020.

Summer Seeding Options for Thin Alfalfa Stands


Multi–Cut Options for Hay or Baleage

  • Warm-season grasses germinate best @ soil temperatures of 62°F+
  • Plant after May 25 in far southern Minnesota. Adjust dates later for more northern latitudes, and earlier farther south.


  • Not frost tolerant.
  • Requires very firm seedbed. No-till into alfalfa stand after first cutting or into worked and packed ground, ⅛” to ¼” deep.Packing afterward should increase germination.
  • Use for dry hay or baleage.
  • Provides high quality forage.
  • Seed 10 lbs/A coated seed in open areas; 5 lbs/A where stand is thin.

Japanese Millet

  • Not frost tolerant.
  • Seed after June 1 in southern Minnesota. Prefers soil temps of 62°F+.
  • Easy to establish; interseed into alfalfa after first cutting or into worked ground.
  • Inexpensive option
  • Seed 25-35 lbs/A in open areas; 15-20 lbs/A where stand is thin.

Piper Sudangrass*

  • Interseed after first alfalfa cutting or seed into worked ground.
  • Coarser stemmed than Japanese Millet, similar to Pearl Millet
  • Can make dry hay or baleage.
  • Seed 20-30 lbs/A

Pearl Millet

  • Interseed seed into alfalfa after first cutting (or following small grain or small grain/pea silage) OR seed into worked ground.
  • Better suited than Japanese millet to drier soils
  • Coarser stemmed than Japanese Millet
  • Not suited for hay; use for baleage or silage
  • Seed 15-20 lbs/A

Sorghum-Sudangrass Hybrids*

  • Interseed into alfalfa after first cutting (or following small grain or small grain/pea silage) OR seed into worked ground
  • Coarser than Piper Sudangrass or Pearl Millet
  • Provides greater tonnage than above options.
  • Brand and variety options:
    • Regular’ – Viking 100: multi-cut
    • BMR
      • Viking 200 BMR: multi-cut. May be able to make dry hay
      • Viking 220 BMR (organic): multi-cut
      • Viking 300 BMR photoperiod sensitive; suited for one big cut in late summer (can be cut multiple times, though)
      • Surpass BMR Dwarf: multi-cut
  • Seed 20-30 lbs/A

Single–Cut Options for Baleage or Silage

Forage Sorghum*

  • Warm-season annual
  • Maximum tonnage of the warm–season annuals:6-9 tons DM/A
  • Can follow with winter small grain fall seeded for silage the following spring
  • Seed 8-12 lbs/A

Milo/Soybean Mix*

  • Summer annual mix
  • Seed after 1st hay cut or small grain or small grain/pea silage or as initial seeding
  • Good tonnage: 5-9 tons/A DM
  • Used for baleage or silage
  • Reported performance lag when switching cattle from corn silage to silage containing soybeans
  • Can follow with winter small grain for silage the following spring
  • Seed 150 lbs/A

Foxtail Millet (Siberian or German)

  • Single cut with little regrowth. Minimal regrowth can be grazed.
  • Handles dry conditions / light soils
  • Fast growing
  • For latest planting; ready to cut for hay in 40-50 days
  • Good for dry hay
  • Can follow with winter small grain fall seeded for silage the following spring
  • Inexpensive
  • Seed 20-25 lbs/A

Manage to avoid prussic acid poisoning

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Managing Stand Losses in Alfalfa FieldsMichigan State University

Seeding Alfalfa Into Alfalfa, University of Wisconsin

Seeding Into an Existing Alfalfa Stand, University of Wisconsin