The frozen ground cracks. Snow melts. And farmers across the Midwest walk their fields with a familiar knot in their stomachs, wondering if their alfalfa survived another brutal winter.
Alfalfa winterkill remains one of the most frustrating challenges facing agricultural producers in our region. The end of 2025 brought early snowfalls, then January delivered extremely cold temperatures for an extended period. Renk Seed is sure there are growers out there wondering what this weather will do to the alfalfa. This is a good time to review causes and recovery from winterkill in alfalfa.
What Really Causes Alfalfa Winterkill?
Winterkill can be hard to predict because alfalfa can fail to survive winter for several reasons. The most common is alfalfa being killed when water in the plant freezes, causing the cell walls to rupture. Alfalfa can also suffocate if it can’t clear toxic metabolites in the winter. Another cause of failure occurs if alfalfa comes out of dormancy in the winter and uses up its root reserves before spring comes. The last common failure is soil heaving forcing roots out of the ground or damaging their structure.
Winter survival starts in the fall. Having good root reserves is the first step. At roughly eight inches of growth the alfalfa plant starts storing reserves in the roots and crown, reaching full reserve potential when the plant is at full bloom. Target 25% bloom for that last cut (or after a hard frost) to provide sufficient root reserves. Also, avoid cutting in September and early October to protect the plants from using up reserves needed for re-growth in the spring. The last cut should leave at least four inches of stubble, important for catching snow and allowing the plant to discharge toxins. Reflecting on these management guidelines, how well did you do setting up the alfalfa for overwintering success?
Following proper management guidance can help a lot in preparing your alfalfa for winter, but the weather is out of your control. A wet fall will leave more water in the plants, making them more vulnerable to freezing injury. Two weeks of temperatures between 5°F and 15°F will kill most varieties. Snow cover can do a lot to shelter your plants, as it is a great insulator and will keep soil temperatures from dropping to these lows. Snow by itself will not smother alfalfa, since air will continue to flow through the layers of flakes.
Sometimes high temperatures can be a bigger problem. Temperatures above 40 degrees can cause alfalfa to break dormancy, eating up root reserves and making the plant more vulnerable to freezing later in the winter. These spikes in winter temperatures can bring rain and melt snow, potentially turning it into ice sheets that cover large areas of your alfalfa. Ice sheets do and will smother plants; this is probably where we have seen the most damage over the last several years.
Assessing Your Stand
Walk your fields when conditions allow.
Winterkill in young stands (following the seeding year) is fixable by reseeding or interseeding new seed. With older stands, you have two options: 1) live with what you have left or 2) rotate out of alfalfa. Plants in older stands secrete autotoxins into the soil, which prevent new seedlings from establishing or severely stunt them. Based on soil structure, the autotoxins can remain in the soil for a year or more after the old stand is plowed up.
Finding Reliable Agricultural Seeds
Successful replanting starts with sourcing quality alfalfa varieties from a trusted seed company. Renk Seed Company understands the specific challenges facing Midwest farmers. As a seed supplier for crop growers and agricultural cooperatives, they provide access to varieties suited for our region's demanding conditions.
Whether you're replacing winterkill damage or planning new seedings, working with experienced seed distribution professionals helps you select varieties with appropriate winter hardiness ratings, disease resistance, and yield potential for your operation.
Moving Forward
Alfalfa winterkill frustrates even experienced farmers. But with careful stand assessment, informed replanting decisions, and quality agricultural seeds, you can recover from winter damage and maintain productive forage production.
Don't let winterkill derail your season. Contact Renk Seed Company at 1-800-Buy-Renk to discuss your alfalfa seed needs. Visit their website at renkseed.com to learn more about available varieties and farming supplies. Their team understands what it takes to establish and maintain productive stands in our challenging climate.
The right seed selection today determines your forage quality tomorrow. Make it count.
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