By Mark Sulc, Ohio State University Extension forage specialist
The recent damp weather has prevented a timely last cutting of hay across much of Ohio. So is it safe to cut a hay stand now? The answer depends on how much alfalfa and red clover is in the stand, how important it is to you to keep the legumes in that stand, and how badly you need or want the extra hay. For pure grass stands, fall cutting concerns are much less of an issue.
Cutting tall legumes like alfalfa and red clover between now and mid-October will carry some risk to the health of the stand. Legume plants are actively storing energy reserves in the taproots during this fall period that are used for winter survival and re-growth next spring. Cutting now will interrupt that storage process because the plant will use reserves for late fall regrowth, and there won’t be enough time to replenish them before a killing frost.
So cutting now will add a stress to the stand and place it in a compromised status going into the winter. This year has been a tough year on alfalfa in particular, with all the wet soil conditions we’ve had. We have observed a considerable decline in stand density in some of our stands this fall, and adding another stress to the stand will likely be harmful to its productivity next year.
I am often asked whether leaving a large amount of fall growth can harm an alfalfa stand in the winter. The fear is that the alfalfa will “smother itself out.” I have let pure stands of alfalfa go into the winter with a lot of growth, and have never experienced a problem or seen the crop “smother out.” So if you don’t need the forage, it won’t harm the alfalfa stand to let it be and not cut it at all this fall.
If you do need the forage or really want to have more hay for sale, then consider delaying harvest to late October or early November. While this increases the risk of bad hay making weather, a late fall harvest is usually a safer alternative to the health of the stand than cutting between now and mid-October, By late harvest, I mean as close as possible to a killing frost of alfalfa, which happens when air temperatures reach 25 F for several hours. Waiting to cut until we are closer to the time of a killing frost will prevent re-growth and loss of energy reserves, and will reduce the risk of less vigorous stands next spring.
I recommend a late harvest option only if the soil is well-drained, the stand is healthy, a variety is planted that has excellent winter hardiness, and the soil has good fertility status. Late cutting on less than well-drained soils increases the risk of winter heaving in alfalfa.
Fall management of alfalfa is one of the few controllable factors that will potentially influence the health of your alfalfa stand next year. It could play a determining role in how much yield you get next year.