Winter Survival of Alfalfa

Alfalfa stands are a valuable resource, and should be managed to ensure their long- term survival. This is especially true where renovation is risky and expensive, such as on erodible, thin, hilly or stony soil. A number of factors combine to affect the winter-hardiness of a stand:

Critical Harvest Period

Cutting or grazing schedules are an important factor in determining winter survival of forage stands. In order to reduce the risk of winter kill, alfalfa should not be cut or grazed during a five-week period before a killing frost. This time allows alfalfa to store food reserves in roots and crowns, and increase winter-hardiness.

Age of Stand

Older stands are more at risk of winter kill than younger stands.

Varieties

Some varieties are more winter hardy than others. Generally, variegated type varieties are more winter hardy than flemish types.

Fertility

Soil fertility, especially potassium (K), is important. Most Manitoba soils have adequate potassium. Sandy soils are most likely to be deficient.

Soil Moisture

Alfalfa on wet soils during winter is more prone to winter kill than on dryer soils.

Winter-injured stands will show signs of yellowing, slow growth, and few stems per plant. Stands may recover if the first cut is delayed until near maturity.