Steve Groff never planned to develop a new variety of cover crop. In fact, the Holtwood, Pa., no-tiller and cover crop expert believes that he is more often recognized for his contribution of the tillage radish as a cover crop in the early 2000s. 

“But even before that, I was beginning to see the value of cover crops and one of the things I was trying to learn about was how to terminate cover crops by rolling and crimping them,” Groff says. “In 1996, I had developed what was probably the first specifically designed roller crimper for cover crops. At that same time, I was looking for an earlier-maturing hairy vetch that was able to be terminated with the roller crimper that I had.”

In the Lab 

It was during this time that Groff was testing different genetics available for earlier-maturing hairy vetch, and he stumbled upon the right combination of genetics for a variation of hairy vetch that he liked.

“I started growing the seed for myself just so I’d have some of it for my own farm,” Groff says.

A couple years later, he noticed that the variety he was growing was drifting toward a longer season compared to the original.

“Then in 2003 or 2004, someone told me that they had planted some of my genetics and they survived the winter, while their other hairy vetches had not,” Groff says. “Until then, I didn’t even realize that it was a better winter hardy variety of hairy vetch because that’s not necessarily what I was trying to do.”

Groff didn’t mind that the variety was trending toward a longer season. In his experience of managing hairy vetch, a little herbicide could go a long way, and the longer and more mature the hairy vetch was, the more biomass and nitrogen it would provide.

“Nitrogen production of hairy vetch is top notch,” Groff says. “The results are always consistent and that’s why it’s a fairly popular cover crop. But the one weakness I noticed was that you can’t plant it later into the fall like some other cover crops. So that’s what I wanted to try to develop and it was just one of those things where you try a few different things and it ends up working out better than you could have expected,” Groff says.

Once word got around that Groff’s variety of hairy vetch was more winter hardy, it got picked up by Penn State University Extension and the Rodale Institute sometime around 2006 or 2007, according to Groff. They conducted a comprehensive study that involved several other universities and farms comparing what was called the “Groff Selection” and other hairy vetch varieties out on the market.

Off & Running

The studies essentially confirmed that the winter survivability of Groff’s variety was always near the top and biomass production was also near the top almost every time. That’s when Groff realized he might be onto something.

“It was at that same time that I was also developing the tillage radish, and this is why I mentioned this because I did not ever intend to develop a variety for the hairy vetch, but I did with the tillage radish, and I understood how this works and how it needs to be done,” Groff says. “A lot of people don't understand that to create a variety under the Plant Variety Protection Act (PVPA), you have to go through an official documentation that involves demonstrating that your variety has at least two distinct phenotype differences than other similar varieties on the market.” 

Groff was able to patent protect his vetch variety and prove that it was distinctly different and more winter hardy than other varieties on the market. But he was curious himself as to why his variety had developed a stronger winter hardiness. He realized that it didn’t have anything to do with being grown in a cold state because his part of southeastern Pennsylvania was far from being the coldest part of the country. Instead, Groff concluded it had to do with the variability of the climate in his part of the country.

“It’s because of the multiple freeze-thaw cycles that I have in my area. That is where the winter hardiness trait was developed,” Groff says. “It’s not about coldness. Those who grow alfalfa understand this because when the ground freezes, it expands, and the roots tear off and it kills a perennial like alfalfa. So you have to breed that trait into it.”

Groff says that most hairy vetch is bred in climates that don’t have a lot of freeze-thaw cycles, such as Alabama and Oregon. Groff attempted to research where in the U.S. has the most freeze-thaw cycles and found a report specifically noting southeastern Pennsylvania as having some of the highest number of freeze-thaw cycles in the country.

“When you’re in Wisconsin or North Dakota, you can get 15 degrees F below 0 and the ground is frozen solid for sometimes months at a time,” Groff says. “There's not a lot of freeze-thaw cycles except at the very beginning of the fall and the end of spring. And then a lot of times there's snow cover, and that's another variable.”

Planting Recommendations

Groff says the general rule of thumb in Pennsylvania is that the first killing frost is around Oct. 20, and a traditional hairy vetch plant date would be Oct. 1 or roughly 3 weeks before the first averagtomatoese killing frost date. But for Groff’s Winter King hairy vetch, there is more wiggle room for the planting date.

“I planted Winter King into November, and it still survived,” Groff says. “Not 100%, but it survives. It does depend on the intensity of that given winter, but we have made a huge leap in terms of survivability when you plant it that late. If we knew exactly what the winter was going to be like — colder than normal or warmer than normal — we could make exact decisions, but hey, that’s farming.”

Groff says the seeding rate depends on a few different factors. For no-tillers who have never planted hairy vetch before, he recommends 20-25 pounds per acre as a good starting rate. He also strongly recommends planting the hairy vetch with a companion crop, a common agricultural practice of planting a crop grown alongside another crop to gain some advantage in yield or crop protection from pests or the elements.

“If you plant hairy vetch with spring oats, for example, and if you get that planted early enough in the fall that it grows, the oats will protect the hairy vetch from the cold weather,” Groff says. “That’s a strategy that you can use to get away with planting a little later and having a higher percentage of survivability. I always recommend a companion crop of some sort.”

Groff says the hardest year to grow hairy vetch is typically the first year. It gets easier each subsequent year, allowing no-tillers to reduce seeding rates by 20-25% after 1-2 years.

“Hairy vetch usually has 3-5% hard seeds, meaning those seeds will not germinate the 1st year and maybe not even the 2nd year either,” Groff says. “So when you plant hairy vetch, 3-5% of it will come up later down the road. If you choose to plant hairy vetch, you might as well put it on the deed of your farm because it’s going to be there for years to come.”

While Groff says this could be a negative for certain small grain farmers, he believes that any serious cover cropper would consider this to be a good thing because in the context of growing commodity crops like soybeans and corn, vetch is very easy to control.

“I think the name Winter King is very appropriate because it can be planted later, and that’s an advantageous aspect,” Groff says. “I continue to work on developing this variety, and there will likely be a second phase in the years ahead. What I would like to do is have this be the winter legume version of cereal rye. That’s a tall order because cereal rye can be planted anytime, but that’s my ultimate goal.”

Groff hopes to have developments on a new version of his Winter King hairy vetch in the next 2-3 years, but he also does not plan to rush the process. He recognizes that agriculture is oftentimes not an exact science and has many variables that must be taken into account.

“It’s my favorite cover crop,” Groff says. “Of course the tillage radish is near and dear to my heart, but hairy vetch is often called the queen of cover crops, and that is absolutely true. Mine just happens to be named Winter King, so it fits well.”

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