By Emma Matcham
This has been a particularly tough year for establishing new alfalfa fields. Much of our region was wetter than normal in the spring, and the southern parts of Ohio received 2 to 4 inches of surplus rain in April alone.
Wet weather delayed alfalfa planting in much of Ohio, resulting in a mix of later-than-normal spring plantings going in during May, and some reports of plans to use a short-season summer annual before trying to establish alfalfa again in August. August plantings also had challenges, with much of our region having hotter, dryer weather than normal.
When the soil is bone dry, seed can sit underground without much damage and then emerge successfully once water is available. Some fields in this situation were saved by September rains. But fields that were either broadcast in dry weather or drilled into some shallow moisture, but then received no rain for a week or longer could not be rescued by rain. Why is that? Seeds need sustained moisture to emerge. If it dries out after the seed starts absorbing water but before the seedling emerges, the growing plant will die and the seed is no longer viable.
Unfortunately, we can’t always predict when rains will be coming at the time we plant. So, how can we evaluate management options for new plantings with poor emergence? The first step is determining which fields have an insufficient stand. Generally, new plantings of alfalfa should have at least 25 to 30 plants per square foot.
Also, take note of plant size — fields with less than 6 inches of above-ground growth will usually have higher winter kill rates.
Autotoxicity
For fields with fewer than 25 plants per square foot, some management options depend on the stand age/planting date of your original stand. If your alfalfa was planted before April 2025, interseeding with more alfalfa is probably not a good option due to autotoxicity concerns. Autotoxicity risk is low in fields planted in August 2025, and interseeding with additional alfalfa seed during the spring planting window for 2026 is a good option (last week of March through late April).
It’s more difficult to predict autotoxicity risk for fields established between our typical planting windows, such as a mid-May through June planting date. Autotoxic compounds are water-soluble, so they may have accumulated more than usual in the first summer of alfalfa growth. The accumulated compounds will likely flush through the root zone after just a few heavy rains on fields with coarser soils, but will be more persistent on heavier ground.
Overseeding
Some management options that are planting date neutral include overseeding. Grasses like orchardgrass or perennial ryegrass are usually the highest-yielding options for adding to a poor alfalfa stand, but cereal crops like oats or triticale can also provide high tonnage.
Overseeding legumes such as red or ladino clover can thicken a stand and provide high-quality forage, but they generally will yield lower than stands that include a grass.
Overseeding with a cool-season species is best performed with a no-till drill in early April, but broadcasting is an option when there’s enough soil moisture for seeds to emerge well.
Future planning
While planning for alfalfa establishment in the future, keep in mind that weather patterns like this will likely occur again.
Long-term weather models for our area suggest that, in general, our springs will continue to get wetter and our summers will continue to get drier. Consider management options that help soil dry a bit faster before spring alfalfa plantings, such as a high-biomass winter cover crop that can help transpire moisture out of the soil.
On some soils, moving to a no- or reduced-tillage system might help you save time during limited workable spring days. One way to mitigate the risk of winter kill from summer plantings with low biomass is using a nurse (companion) crop like oats or barley, since they can help retain snow and protect the alfalfa plants from wind and other harsh winter conditions.
Not all solutions will work for everyone, but I do think it’s valuable to think about ways to be more resilient against these sorts of weather patterns.
(Emma Matcham is an assistant professor in the Horticulture and Crop Science Department at The Ohio State University.)
