Selecting the right alfalfa cultivar is one of the few irreversible decisions a producer makes. To maximize stand longevity and forage yield, you must select a variety adapted specifically to your local climate.
According to Mike Trammell, Oklahoma State University southeast area agronomy specialist, two of the most critical factors to evaluate are winter survival and fall dormancy.
“Although fall dormancy is somewhat related to winter hardiness, it is not an accurate measure of it,” Trammell explains. “Winter hardiness and fall dormancy should be considered as entirely separate characteristics when selecting alfalfa varieties.”
What Is the Alfalfa Winter Survival Rating?
Trammell says alfalfa winter survival is the ability of an alfalfa plant to withstand extreme freezing temperatures during the winter without suffering severe bud injury or plant death. Because the buds for spring growth form during the previous autumn, winter survival directly impacts your stand’s persistence and early-season yields.
Winter survival is measured on a scale of 1 to 6, with lower numbers representing the highest cold tolerance.
Table 1: Alfalfa Winter Survival Ratings & Regional Adaptation
| Rating | Description | Region of Adaptation |
| 1 | Extremely winter hardy | Northern Plains |
| 2 | Very winter hardy | Northern Plains / Upper Midwest |
| 3 | Winter hardy | Northwest / Upper Midwest & Central Plains |
| 4 | Moderately winter hardy | Transition zones / Central U.S. |
| 5 | Slightly winter hardy | Southern U.S. |
| 6 | Non-winter hardy | Extreme Southwest U.S. |
Note: For detailed regional recommendations, consult the National Alfalfa and Forage Alliance (NAFA) Alfalfa Variety Ratings Guide at www.alfalfa.org.
What Is the Alfalfa Fall Dormancy Rating?
According to Trammell, fall dormancy is how an alfalfa plant responds to decreasing day lengths and falling temperatures in the autumn. It determines how quickly a plant stops growing in the fall, how early it starts growing in the spring, and how rapidly it regrows after harvest. Fall dormancy is rated on a scale of one to 11.
“Fall dormancy ratings are a particularly good indicator of yield potential,” Trammell says. “The advantage of growing varieties with a higher fall dormancy rating is generally higher yields because the plant is active for more days of the year.”
However, if a rating is too high for your region, Trammell explains the plant may break dormancy during a winter warm-up and suffer severe frost damage.
Table 2: Alfalfa Fall Dormancy Ratings
| Rating | Description | Growth Characteristics |
| 1 – 2 | Very dormant | Slowest regrowth; earliest fall shutdown; lowest yield potential |
| 3 – 4 | Dormant | Standard winter protection; moderate growth period |
| 5 | Moderately dormant | Balanced dormancy and yield potential |
| 6 – 7 | Semi-dormant | Extended growing season; rapid regrowth |
| 8 – 9 | Non-dormant | Longest growing season; highly productive in mild climates |
| 10 – 11 | Very non-dormant | Minimal to no winter dormancy; maximum yield potential |
Visual evidence of these differences can be seen in the photo above.
Summary Checklist for Selecting Alfalfa Seed
When choosing your next cultivar, Trammell recommends balancing these ratings with your specific operational goals:
- Prioritize Winter Survival First: Ensure the variety can survive your region’s coldest winters. In northern climates, look for lower survival ratings (1–3).
- Select the Highest Safe Fall Dormancy Rating: To maximize yield, choose the highest fall dormancy rating that your local winter climate safely permits without risking winterkill.
- Factor in Secondary Traits: Once adaptability is established, filter options based on intended use (hay vs. grazing), pasture management style, and local pest and disease resistance needs.
Where to Find Verified Alfalfa Variety Ratings
To compare certified alfalfa varieties, access the interactive database published annually by NAFA. This tool allows producers to search and filter certified seeds by winter survival, fall dormancy and pest resistance.
