Alfalfa has two main planting windows in Ohio—early spring or later summer/ early fall. The Ohio Agronomy Guide recommends planting dates between August 1st and August 15th for northern Ohio, and planting dates between August 1st and August 30th for southern Ohio. Below are a few considerations for successful late summer establishment.
Site Selection: Alfalfa requires adequate soil moisture to establish well, but it’s not very tolerant of wet feet especially in winter. Choose a well-drained site, but truly droughty soils may be a better choice for spring-established alfalfa than August-established alfalfa.  Like most legumes, alfalfa requires a pH above 6.0. Productivity will be best when pH is 6.5 (when subsoil pH > 6.0) or 6.8 (when subsoil pH < 6.0). Learn more about alfalfa’s soil fertility requirements in the Tri-State Fertilizer Recommendations. Check your herbicide records to make sure any herbicide rotation intervals have elapsed (summary table of some common herbicides is available at http://go.osu.edu/herbrotationintervals).
Field Preparation: Glyphosate is a good option for pre-plant burndown (other weed control options are listed in the further reading section, below). Consider a no-till seeding to help conserve soil moisture, although tillage may be necessary to control herbicide-resistant weeds or in fields with a history of sclerotinia crown and stem rot. Using herbicides and/or tillage for field prep is important, since root-feeding insects can become a problem when alfalfa seedlings emerge in a field that has pre-existing living roots.
Seeding Recommendations: For a pure stand of alfalfa, aim for approximately 80 seeds/ square foot, or around 15lbs/ acre. Coated seed will be heavier, so account for its weight when calibrating your drill. Seed should be placed around ¼ or ½ an inch deep for most Ohio soils (aim for ½ to ¾ inches on sandy soils). Avoid planting too deep by making sure that some seed is still visible on the soil surface, especially in no-till plantings.
Management Considerations for Fall: Do not plan to harvest August-planted alfalfa until next spring—cutting in fall will reduce winter survival. Scout your fields to determine if a post-emergence herbicide will be necessary to control fall broadleaf weeds, and review herbicide options in the 2025 Ohio Weed Control Guide. Â
Further Reading:
Ohio Agronomy Guide, 16th Edition. https://extensionpubs.osu.edu/ohio-agronomy-guide-16th-edition/
Tri-State Fertilizer Recommendations for Corn, Soybean, Wheat, and Alfalfa. https://extensionpubs.osu.edu/tri-state-fertilizer-recommendations-for-corn-soybean-wheat-and-alfalfa-pdf/?searchid=0&search_query=974
2025 Ohio, Indiana, Illinois, and Missouri Weed Control Guide. https://extensionpubs.osu.edu/category-2c-agricultural-weed-control/
 Herbicides for Alfalfa—a resource from Kansas State University. https://www.frontierdistrict.k-state.edu/crops/crop-production/docs/Alfalfa%20weed%20guide.pdf