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“There’s something almost magical about a tomato planted after hairy vetch.”

— Steve Groff, Grower, Holtwood, Pa.

In this episode of the Cover Crop Strategies podcast, brought to you by Montag Manufacturing, listen to a conversation with cover crop expert Steve Groff, who farms in southern Lancaster County, Pennsylvania. Steve talks about how he first came up with the idea to grow his Winter King hairy vetch — a particularly winter-hardy variety of cover crop that is able to survive repetitive freeze-thaw cycles. 

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The Cover Crop Strategies podcast series is brought to you by Montag Manufacturing.

Montag precision metering equipment is helping producers achieve their yield goals while saving on seed and input costs. For establishing cover crops, Montag’s family of seed platform equipment adapts to a variety of major brand delivery systems that will conserve seed and nutrients along with soil and water. Explore new options for your production and conservation goals with your Montag dealer, visit or call Montag at (712) 517-2775.

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Full Transcript

Mackane Vogel:

Welcome to the Cover Crop Strategies Podcast, brought to you by Montag Manufacturing. I'm Mackane Vogel, Associate Editor at Cover Crop Strategies. In this episode, listen to a conversation with cover crop expert Steve Groff, who farms in Southern Lancaster, Pennsylvania. Steve talks about how he first came up with the idea to grow his Winter King Hairy Vetch, a particularly winter-hardy variety of cover crop that is able to survive repetitive freeze thaw cycles.

Steve, I want to start the interview off same way I start most of these and tell us a little bit about yourself, and my favorite question, tell us your ag origin story, so tell us some of your earliest memories of farming?

Steve Groff:

Well, I appreciate this opportunity and to answer your question, earliest memories of farming, I would say this, to preface at all, there's never a day that I really didn't want to do anything other than be a farmer, and I'm a third generation on this particular farm here, so that gives you a little bit of a background. I remember at a very young age, five years old, back as far as I can remember I guess, just helping out and my parents gave me that opportunity and I appreciated it. And to that end, I've tried to, I guess you'd say continue the legacy with my son, and now he has a son, I'm a grandpa. It's really cool, it's really gratifying to see the multi-generations to be involved.

Yeah, a farm here in Southern Lancaster County, Pennsylvania, we have a farm of 200 acres, vegetables, hemp, small grains, everything has been 100% no-till since the mid-nineties, and very intensively cover crop, which we're going to talk about today. Started my first no-till in 1982, and so I have some fields, this is our 42nd season going into 100% no-till. So really proud of that, I've certainly learned a lot over those decades and continue to learn more every day.

Mackane Vogel:

All right, well as you alluded to, today we're going to talk a lot about your Winter King Hairy Vetch. So why don't you give us just kind of a brief overview of it and then I'll kind of follow up with some more specifics and we can get into the nitty-gritty. But tell us, just for those who don't know anything about it, give us a brief overview?

Steve Groff:

I never planned to develop a variety of a cover crop. I'm probably more noted for the tillage radish that I developed back in the early 2000s, but even before that I was beginning to see the value of cover crops. And one of the things in the cover crops, one of the traits of trying to learn how to use them was in the context of rolling and crimping cover crops. In 1996, I have what was probably the first specifically designed roller crimper for cover crops that I developed. And what I was looking for at the time was a earlier maturing Hairy Vetch that was able to terminate with the rolling stalk chopper, the roller crimper that I have. And so I was testing some different genetics for that that were available, and there wasn't many in the mid-nineties, but I stumbled upon some that I liked and I started growing the seed for myself, just to grow the seed so I'd have it my own.

In the early 2000s, I noticed that my variety was drifting to a longer season. It wasn't as short of a season as it was before, because I was comparing it to actually the original, where it came from, and also some others were coming out in the market. I was working with, way back then, Dr. Thomas Devine from Beltsville, Maryland at the Agriculture Research Center, he was very interested in researching Hairy Vetch. And later, Stephen Mersky, he has been doing it, so I was very working very closely with them. And it was about, I'm going to say 2003, 2004, when someone else told me that they had planted some of my genetics and they said it survived the winter, where the other Hairy Vetch did not. And I said, "Oh, really?" Because I did not honestly know that it was a better winter-hardy Hairy Vetch because that's not really what I was trying to do.

The other thing I'll mention at this point in my story is I didn't really mind that my variety was drifting to be a longer season because I found out that in managing Hairy Vetch, a little bit of herbicide goes a long way, plus I got the benefit is depending on the spring, depending on my planning schedules, rather than having a vetch bloom earlier, I would rather it go longer and more mature so it could grow more, so it could grow more biomass and hence more nitrogen. So actually it's one of those things where you try things and it kind of works out different but yet better than you expected. So then when I heard that the variety I had was better winter-hardy, it was picked up by Penn State University and the Rodel Institute. In years 2006, 2007, I believe those are the correct years, they did a pretty comprehensive study that involved some other universities as well around the nation where they used what they called the Groff Selection, which was mine, and they compared it to other Hairy Vetches that were out on the market.

And it was basically confirmed that the winter survivability was always near the top. It wasn't consistently the top one, but it was always near the top, and biomass production was very good. Again, not the winner in all the plots, but it gathered some attention. So that is kind of what I thought, "Well, I might have something here." That was the time 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.

A lot of people don't understand that to create a plant variety, protected variety, a PVP variety, you have to go through essentially an official documentation. And simply what that means is you need to demonstrate that your variety, whatever you're working on, that there's at least two distinct phenotype differences than other similar varieties on the market. So I was able to do that, and it was not hard to prove that my variety was better. I'll say a little caveat, the first year we did this, my variety survived the winter and all the other ones did not, which I thought, "Well, that's awesome, proves my point." But in the context of the way things are required to do, they had to do the experiment or the research again basically to prove it, and so it was delayed a year because of that. And you have to do official license, seed breeders to do all this stuff. A lot of people don't understand what's behind all this, and that's why I'm sharing this here.

So finally I was able to get it plant variety protected and I have that patent on it. So then I started continuing to... Well, I'll just stop right here and say one thing, why did my variety develop a stronger winter-hardiness? Because I'm not the coldest part of the country by far. I'm in Southeastern, Pennsylvania, we've just been re-designated to Zone 7A in the winter-hardiness zone, in case anybody understands that and knows what that is. So we have snow cover on and off through the winter and all those factors that went into winter survivability, but it was during a time where I tested some varieties from, many of you know Dwayne Beck. And Dwayne Beck sent me some lentils, some winter lentils that he said, "These work great in South Dakota, you ought to try them in Pennsylvania."

I tried them and I'm thinking, "Well, if they survived South Dakota winters, this is a piece of cake." They did not survive my Pennsylvania winter and left us scratching our heads two years in a row, and we came to the conclusion that it's because of the multiple freeze-thaw cycles that I have in my area is where the winter hardiness trait was being developed, not coldness trait, because again, I'm not the coldest. And those who grow alfalfa understand this because that's a big thing with alfalfa or they call it heaving, when the ground freezes, it expands and the roots tear off, and it kills a perennial like an alfalfa. So you have to breed that trait into it. So we got to thinking maybe this is the selection that was used.

You see, most Hairy Vetch, almost all Hairy Vetch has been bred in climates that don't have a lot of freeze-thaw cycles. A lot of it's been bred by Auburn down in Alabama and in Oregon, and Oregon doesn't have as many freeze-thaw cycles as I do here in my location. So that is, we think why, and I actually looked up, and this was a little difficult to find, but I looked up where are the most freeze-thaw cycles in United States? And I did run across a report on that, and yes, right where we're located here in Southeastern, Pennsylvania, we have some of the most highest number of freeze-thaw cycles of anywhere there is. So when you're out in the Midwest and you can get 10 below zero, 15 below zero, wind chill and all that, the ground is frozen solid for sometimes months at a time, there's not a lot of freeze-thaw cycles except at the very beginning in the fall and the end and the spring. And then a lot of times there's snow cover, and that's another variable. So I know I'm getting long-winded here, but it's an interesting part of the story of how this developed. So you may have some questions, but then I can follow through with how I got the variety and everything, the name and all.

Mackane Vogel:

Yeah, so good start. So just to clarify, I guess it's just the fluctuation kind of in temperature in the East Coast more so than somewhere like the Dakotas, or Wisconsin, or whatever that kind of gives it that survivability, is that right?

Steve Groff:

That's what I'm almost 100% convinced why this continues to work and why this trait was bred in. And really the only way you can do it unless you do it in a highly controlled situation is in these actual regions. And this is a case here for what we use now epigenetics, a term that you perhaps will start to drift toward the propensity to survive in a given climate, so it's a case in point. Now that doesn't mean they can just be used here because my variety has been used all across the US. And I'm not claiming that it is the best cold survivor, because that's not what I selected it for, but there is a relationship to the freeze-thaw cycles that can transfer to that. And I'll just say that it is done very well in that dynamic of survivability for the winter.

And being able to be planted later, that's another thing and I think the name Winter King is very appropriate because it can be planted later, and that's really an aspect that becomes advantageous. And I'll just say right now, I continue to develop this variety and there'll probably be a second phase of it coming out in the years ahead. What I would like to do is to be the winter legume version of cereal rye. Now that's a tall order because cereal rye can be planted any time, but that's the goal I have. So going to continue to test and work at it and see where we go from there.

Mackane Vogel:

We'll come back to the episode in a moment, but first I'd like to thank our sponsor, Montag Manufacturing for supporting today's podcast. Montag precision metering equipment is helping producers achieve their yield goals while saving on seed and input costs. For establishing cover crops, Montag's family of seed platform equipment adapts to a variety of major brand delivery systems that will conserve seed and nutrients, along with soil and water. Explore new options for your production and conservation goals with your Montag dealer. Visit or call Montag at (712) 517-2775. And now let's get back to the episode with Steve Groff. You mentioned planting date, when do you typically plan it and at what rate?

Steve Groff:

20 or 30 years ago, the general rule of thumb for my area here, and I'm going to say so everyone can reverse it to their area, first killing frost is average October the 20th in the fall, so just keep that in mind. So our traditional Hairy Vetch date, October the first, done, no more. That's traditional, so let's just say three weeks before the first average killing frost was traditional. I planted the Winter King now into November, and it survived. Now not 100%, but it survives and it does depend on the winter, but more so than not we have definitely made a huge leap in its survivability when you plant it that late. So farmers have to assume the risk. We know exactly what the winter would be, is it going to be warmer than normal, colder than normal? You could make exact decisions, but hey, that's farming.

All I'm saying is this variety has the propensity to survive better, there's a higher chance of survivability. You asked about the seeding rates. Here's my comment on that. For people who've never planted Hairy Vetch before, 20 to 25 pounds per acre, seeded solid is a good starting rate. I always recommend and would encourage you to plant with something else. And I'm going to bring up another point here. If you plant Hairy Vetch with spring oats for example, if you get it planted early enough in the fall that it grows, it will indeed protect the Hairy Vetch from the cold weather. So that's a strategy to get away with planting a little later and having a higher percentage of survivability.

I will say in the context of all I've said so far, my breeding efforts have been in the context of a companion crop of some sort because that's what I'm recommending, so that's what I want to do. But also my comparisons as well with other varieties have been in the same. So I'm just trying to give you all the transparency I can give you here today about the formation is. So based on that, it depends on what your companion crop is. So if you're doing it with triticale, cereal rye, if you're mixing some other legumes, it is going to vary. But let's just say for instance this is your first time ever planting Hairy Vetch, and it's in a mix. Let's say we choose 10 pounds or 12 pounds per acre of Hairy Vetch. Once you grow Hairy Vetch a year or two, the rhizobia that that produces is in the soil, and I will say it's important to inoculate, that's really what I'm talking about here, and I would encourage continued inoculation.

That being said, the hardest year to grow vetch is the first year. The seeding years after that, it grows easier, it grows better. So you can reduce your seeding rates, 20%, 25% in the subsequent years. The other thing I have to say now, and this, for some people, this is negative about Hairy Vetch. Hairy Vetch usually has 3% to 5% hard seeds, meaning those seeds will not germinate the first year, maybe not even the second year. So when you plant Hairy Vetch, 3% to 5% will want to come up later on down the road. So you could say, "Well, then it'll become a weed." Well, okay, it depends how you look at it. In the context of growing or commodity crops, corn and soybeans, it's very easy to control, so I'm going to say there's no issues there. Plus I would say that's actually a gift, it's a bonus, that is essentially free seed.

So I have planted Hairy Vetch on every single field of my farm here, and I don't have to look hard to find it growing here and there. So I'd like to say that if you plant Hairy Vetch, you could go and put it onto the deed of your farm, that you plant Hairy Vetch because it's going to be there for years to come, and so that's just one thing that comes with/ I will say this, is any serious cover cropper does not see this to be a problem. There could be an issue out there in small grains because Hairy Vetch will grow right with small grains and it'll be mature around the same time most small grains are ready to harvest and the combine will not pick them out.

Now there are seed separators that will, but you can't do that if your commodity crop, wheat or triticale, whatever your grain is, you don't want that. And trust me, the little black Hairy Vetch seed, you could spot them easily, you're not going to get away with it if you're selling it. If you're organic in particular and don't have the availability of herbicides, this could be a problem if you're selling to a market that requires 100% pure seed of grain. So it's important to understand. That being said, there are many small grain herbicides that can take Hairy Vetch out. So again, it's a management issue, it comes along, you buy Hairy Vetch, this is the management that you have to do with, it doesn't matter what variety we're talking about here. So that's just a long-winded answer there for your seeding rate question.

Mackane Vogel:

All right, well let's go back to the chronological timeline of this story for a sec then, and tell us a little bit about when you started to see major changes in survivability and what happened next?

Steve Groff:

Well, the first ones was back when someone told me, I'm going to guess the early 2000s in there. It was 2006 and 2007 I mentioned about doing that. That was when we, "Okay, let's do some research on this and let's make this official." And then that was again during the time where I was developing the tillage radish so I got an understanding of how to make a variety. So then I proceeded to get it, varietized, got the plant variety protection on it. I think that was around 2010 or so, and I sold some seed, I grew some seed myself, but then I was at the point where I knew that it would be better for me to license the variety to someone else that could get it literally around the nation, around the world, if you will.

So I made an agreement with Smith Seed Services from Halsey, Oregon. They're one of the major seed suppliers to seed dealers. Not every farmer has heard of Smith Seed Services, but they may have used seed to come from because they do direct marketing of their own brands and stuff and you can go on their website and see the Winter King, but they sell Winter King through their dealerships located around the country. So that's currently where I'm at with it. So I've licensed the variety to them, they take care of it all, and so I continue to develop it, to refine it, to improve it, and that's something I love to do. I love to be in the cutting edge of those kind of things and then have someone else be able to market it, so that kind of fits my style.

Mackane Vogel:

All right, let's go back to kind of the climate aspect of this for a second. So obviously you mentioned the lots of freeze-thaw cycles, that's kind of how it came to be, but what climate would you say the variety is best for, or does it work anywhere? Is it a one size fits all? Talk about that a little bit?

Steve Groff:

Yeah, so obviously the correct answer to that would be a climate like mine where it was bred and done. But I can tell you this, it's been used all over the country, and I haven't heard of any major negative feedback on it, that it didn't grow, I haven't heard of any. Like I said, again, like any variety out there, anybody who claims they're the best of the best, they're fooling themselves. I'm just making the claim that this is a pretty good one here, one of the best for anywhere in the country. Maybe in the south I don't know if it's going to have that trait, is going to be helpful or not, but it grows in the south, I can tell you, but the trait that it's known for won't need to be utilized if you're in a I-20 I-10 corridor. So again, you can hear I'm not a very good salesman, I'm a farmer, I like to say it like it is, but the variety has performed well in those colder climates. And I would say too, there's just some limitations to cover crops that we all know, because if you have planted let's just say late in October in North Dakota, and there's no snow cover, and it's 30 below zero and windy, I don't think it'll survive, no vetch is going to survive in that situation.

Mackane Vogel:

And then in terms of termination, I know you mentioned the crimper and then also herbicide, but what's the best way to terminate it?

Steve Groff:

That depends on what the objective of the grower is. Of course, if you're organic, you don't have a choice, pretty much a roller crimper. If you're no-till, any organic person probably if they work with vetch knows it's either no-till or moldboard plow with vetch because it's such a tangly mess that if you just disc it, it can be difficult to plant anything through. So yeah, it certainly has worked, but I will say that any variety of Hairy Vetch has to be delayed for roller crimping until it's full bloom. It will tend to come back, especially if it's on the wetter side, and that's just simple cover crop management there. Most people we're at the point now, there's been enough of research, enough of articles, enough of farmers who have experienced to actually know that.

Then I like to say with roller crimping, a little bit of herbicide goes a long way. And so I'll also say with herbicides, you don't need any crimping, that plant just collapses, it's so fragile. Unless you have it with a cereal rye or a grain, any grain, then it climbs up and then you have to deal with the other part there. Then you will have to roll it so it doesn't shade out the crop after you plant it. So again, it varies a lot, to answer your question, it's going to have to depend on what the objectives of the farmer is, decide what to do. There's a lot of options.

Mackane Vogel:

Sure. Have you found certain cash crops to be better than others in terms of planting them after the vetch?

Steve Groff:

Yeah, actually for one thing, when I first was introduced to Hairy Vetch in 1994, it was a fellow by the name of Dr. Aref Abdul-Baki Working at the USDA Beltsville, Maryland in no-till tomatoes. That's where I first heard about it and that's when I started doing this. And he said something that at first I didn't know to believe it or not, but I've come to believe it. There's something almost magical about a tomato planted after Hairy Vetch, and I've done the plots with and without Hairy Vetch with others, and you can just see it to the row. So that is really, really cool to see, so tomatoes and Hairy Vetch.

Corn, it does well. It's a legume, it fixes a lot of nitrogen. And I'm going to say one other thing here that's interesting. I went to Argentina a couple of years ago to speak about using cover crops, and when I was there, it was actually planting season and they were planting soybeans into Hairy Vetch. And I said, "Why are you doing this, because we have found soybeans do very well after cereal rye?" Now soybeans are a legume, they don't need the nitrogen necessarily. And their comment was they get paid on protein content of their soybeans, that's a payment bonus you can get. And the Hairy Vetch, because there's nitrogen there, bumps up their protein a couple of points in their soybeans. So their preferred cover crop before soybeans is Hairy Vetch. I had never known that before and I thought that was very interesting to learn that it could be something that our American counterparts here should try or at least mix it with cereal rye if you can get it planted in the fall.

So that was interesting. Now some know that I also grow hemp, industrial hemp, CBD hemp, and I was told numerous times by people who knew and literature I read that hemp has a very similar fertility need as tomatoes. Well, that fit me well because I'm a third generation tomato grower. And sure enough, I can tell you today after five years of growing industrial hemp, that Hairy Vetch is really good before hemp. And again, I've done plots, I've seen it. So to answer your question, there's a lot of crops that benefit from Hairy Vetch. It is my favorite cover crop, of course tillage radish is near and dear to my heart, but it's the queen of cover crops, Hairy Vetch has been listed as that, and I'll say that's absolutely true. I just happen to have the name Winter King, it fits well.

Mackane Vogel:

All right, well let's talk a little bit about the soil health principles here. So you mentioned nitrogen, but what does it do for the soil and what are some of the nutrients that it adds for the following crops? Or I guess further along that same line, what would you say is the biggest soil health benefit of having that Winter King Hairy Vetch?

Steve Groff:

Well, no doubt about it, its nitrogen production is the top. I also felt, and it's a little hard to quantify, that it helps to make available other nutrients. I'm not going to say that's a fact but I will say that is probable because I've seen it here at Penn State, and I've seen it elsewhere, studies have shown that Hairy Vetch will increase corn yields by 20 bushel per acre, and it's not necessarily the nitrogen effect, because they also apply nitrogen to it and additional nitrogen to actually see that. So there's obviously something else going on, and to me, unquestionably, if I had to have one legume cover crop, it would be Hairy Vetch.

To answer the specifics from a scientific standpoint, what else does it do? It does something that I am not totally aware of but I'm telling you the results are always consistent that Hairy Vetch brings to us. So that's again, I think why it's become a fairly popular cover crop, and this is where I addressed one of the weaknesses, is you can't plant it later into the fall like some other covers, and that's what I tried to develop here with this Winter King variety.

Mackane Vogel:

You mentioned that you're kind of still doing some more research on new versions of it. Is there a set number of additional breeding cycles that you're hoping it'll take before it's ready, or I guess what's the timeline look like for that?

Steve Groff:

I'm not going to say the timeline because I don't know. I would say in a couple of years. Two to three years is what I'm going to just say, don't hold me to it, but I have seen that it has advanced, I can tell you that. But when you work with nature and biology, and everything like that, it is not an exact science. I want it to be unique, better, an improvement enough that it's noticeable. But I'm also aware that it depends on the given winter, the given area if you're going to notice a difference. In other words, a mild winter, you may see no difference with any Hairy Vetch variety, let alone mine and my improvement coming along.

So again, that's why farmers I think understand that when it's explained to them, but when you make a claim that it's improved, the only way you're going to see the improvement is when you have a somewhat challenging year. So that's just something I'm going to put out there to understand and that's just important to have that information to know. That's why I'm not in a hurry to get an update, but I'm also saying I'm getting close.

Mackane Vogel:

All right, and lastly, I guess, what would you say is either the most interesting or the most surprising thing that you've learned over the last 20, 25 or so years of breeding it?

Steve Groff:

I think I can summarize in what the theme is here. I did not expect number one to develop a Hairy Vetch variety. And then when I decided to, what happened actually I had to figure out later, why it happened. In other words, I did not think, "Oh, I'm at the perfect spot in the United States to grow a winter-hardy Hairy Vetch." That was not even a thought in my mind, so that's probably what surprised me. And I guess some would say I got lucky. I would say I just took advantage of an opportunity and so happened to hit it. So there you have it. It takes its twists and turns and we ended up in the good side of this journey.

Mackane Vogel:

That's it for this episode of the Cover Crop Strategies Podcast. Thanks to Steve Groff for that great discussion. The full transcript of the episode, as well as our archive previous podcast episodes are available at Many thanks to our sponsor, Montag Manufacturing, for helping to make this Cover Crop Podcast series possible. From all of us here at Cover Crop Strategies, I'm Mackane Vogel, thanks for listening and have a great day.