August 19, 2011

As September approaches, it's time to decide when to take your last cutting of alfalfa. When you take it will affect your alfa's  survival this winter and its vigor next spring. Alfalfa needs about six weeks of uninterrupted growth in the fall to become fully winterized. This winterterizing generally begins about three weeks before the average date of first frost. Your last harvest can occur anytime before winterizing begins or after the winterizing period is over with little worry about affecting stand life. But, harvest during winterizing can be risky.

The degree of risk depends on how much stress your alfalfa experienced this year and, most importantly, the number of cuts you took. Fields cut four or five times are more susceptible to winter injury than fields cut three times or less. Also, young stands of winterhardy, disease resistant varieties are less stressed and can be harvested during winterizing with less risk than older stands of disease susceptible varieties that are only moderately winter hardy.

Also consider your need for extra alfalfa or its cash crop value. Dairy hay is priced high, so cutting dairy hay from this final harvest may be worth the risk of lowering next year’s yield. This year, stock cow and grinding hay also are relatively expensive so it might be worth cutting during winterizing. When this hay is plentiful and reasonably priced, it may be better to buy extra hay rather than risk another cutting.

Remember, you can cut after winterizing with less risk.

Harvesting alfalfa during its winterizing period is risky, but by reducing total stress, you control how risky it is.

Bruce Anderson
Extension Forage Specialist