When's the Right Time to Seed Forages in Late Summer?

August and September give many producers across the Midwest another window of opportunity to establish perennial forages. Not only does this time of year fit well into many cash crop rotations (like after small grain harvest), but other advantages exist when seeding in late summer compared to spring:
  • Late summer planting usually means less competition from winter and summer annual weeds
  • Warmer soils usually equate to quicker, more even germination and resulting establishment
  • For legumes, warmer, dry soils usually lessen issues we face with many root rots and “damping-off” diseases – compared to cooler, wet soils we see in spring
  • More time! Since growers aren’t as concerned with field work associated with spring planted cash crops, less short-cuts happen… forage plantings demand the same effort as any other important crop
A common concern is perceived lack of (consistent) moisture. With many forage seeds planted only ¼” deep, sufficient soil moisture is critical. It makes sense to plant into some level of soil moisture or in advance of a rain event.

The industry often says “fall seeding”, however "late summer" is the more appropriate term and more agronomic too. Research from across the country shows both legume and grasses yield much more prior to winter and the following spring when seeded earlier in the Aug./Sept. window. Legumes especially need adequate time for proper contractile growth (alfalfa) and crown development (clover) – critical to stave off winterkill.
This map illustrates these corresponding dates across much of the Midwest. Recommended late summer seeding dates for alfalfa. Source: Dan Undersander, Univ. of WI. 
These recommendations for alfalfa and all perennial forages are largely based off the average first frost dates across the country – a fact we focus on often when the topic is cover crops. Root systems for perennials usually need 6-10 weeks before our first frost to guarantee overwintering.
Additional Late Summer Forage Seeding Reminders:
  • Plant/drill into a FIRM seed bed. Seed-to-soil contact is the name of the game with any seeding, and late summer is no different. REMEMBER – once the planting is done one should be able to bounce a basketball on your seeded field. If that can’t be done, then soil isn’t firm enough.
  • Inoculate legumes. Nearly all alfalfa and red clover we sell comes pre-inoculated, but not all legumes can be inoculated prior to seeding. Adding fresh inoculant makes sense – it’s inexpensive and helps legumes establish properly. Don’t forget, our LINK inoculant treats most forage and cover crop legumes.
  • Consider recent herbicide applications that may threaten new forage seedings.  Herbicide labels are the law and are meant to keep herbicide residues out of forage crops and subsequent animal tissue. University of Wisconsin has great info on this.
  • Lastly, concentrate on fertility. With alfalfa, pH must be above 6.5 and ideally closer to 7.0. For many forage grasses and other legumes, pH levels above 6.0 should be sufficient. General rules for phosphorus (P) and potassium (K) are:
    • Add P to soil with levels less than 25 ppm (50 lbs/acre)
    • Add K when levels dip below 125 ppm (250 lbs/acre)

About The Corner Post

The Corner Post is a periodic email series with timely forage tips from the agronomic experts at Forage First and La Crosse Seed. If you have a question you’d like us to answer, contact us here.

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