Speaker: Kate Cassity-Duffey, University of Georgia Department of Horticulture
Recorded introduction: Narrated by Bethany Harris
Moderator: Gabrielle LaTora, Agriculture and Natural Resources Agent, Fulton County, Georgia
Duration: 20:18.5
Series: Cut Flower Symposium
Segment: 04 of 08
Webinar Date: July 23, 2026
CEU Categories: [PENDING]
Introduction and Recorded Bio
Gabrielle LaTora: We have Dr. Kate Cassity-Duffey from University of Georgia’s Department of Horticulture. So Dr. Cassity-Duffey, I think that you have an intro video coming up, and then the floor is yours.
Recorded introduction, narrated by Bethany Harris.
Bethany Harris: Dr. Kate Cassity-Duffey is a University of Georgia horticulturist specializing in organic vegetable and cut flower production with a focus on soil fertility and nutrient cycling. She teaches, conducts research, and provides outreach to farmers and extension educators across Georgia and the Southeast, working to make organic production more profitable. Today she highlights field-grown sunflowers and lisianthus.
Part One, and Why Snapdragons
Kate Cassity-Duffey: Hey y’all. Thank you so much for having me and that was great to hear what’s coming out of the University of Tennessee. So I’m going to give you part one of my presentation today since we’re having some technical issues. And I’m actually going to talk about snapdragons. So we’ve been doing some work on snapdragons. I’m going to share my screen. I’m assuming you guys can all see that.
I’m Kate Cassity-Duffey at the University of Georgia. I’m really a soil scientist by trade, but work a lot with organic producers, and that’s how I got involved in cut flower production. So I’m going to talk to you about organic production and how cut flowers play into that and how that might be different than conventional production. Talk about our snapdragon trials.
We’ve done two different trials this year, one looking at the high tunnel versus the field and one looking at eight different cultivars and two different plant dates. And then later on I’ll talk to you guys about our work looking at lisianthus and then also sunflowers and organic fertility, which I think will play well into Celeste and Natalie’s work.
Organic Cut Flower Production in the South
Why Organic Growers Are Adding Cut Flowers
All right, so organic production. So I primarily work in vegetables, but I work with a lot of small to mid-sized scale diversified vegetable growers. And as we’ve talked about, we see this increasing interest in cut flower production. And so many of our growers are adding them on as a value-added product to their vegetable production. And I’m finding that over time this is making up a larger proportion of their production. So it’s a part of CSAs, it helps bring people to the table at the farmers market. Our growers can get a premium with local florists, and consumers often want locally produced flowers.
But how can that be done in organic systems? Most of our information is actually done in conventional systems. All right.
High Tunnel or Field, and Why the South Is Hard
So in our organic cut flower systems. We often produce them in the greenhouses or polyhouses, right? But we know that this can be expensive and not accessible to small growers. So sometimes we have to think about how do we optimize this high dollar space with a high dollar crop. So we want to make sure we’re making the choices that we need to get these crops in high tunnels versus field conditions.
Now, I think everyone here knows that field production in the South can be very challenging. This is especially true in organic production where we don’t have organic pesticides, we don’t have very strong pesticides always. But we also have some other issues in the field here in the South. We know that the high light, the long days, can increase light and shorten our stems for cut flower production, which isn’t always optimal. And we typically see somewhere around 60 centimeters for commercial grade stem length for most of these cut flowers. We also see in field production that we have damaged or tattered flowers. And there’s not a lot of information on plant date for our southern growers. We can take what we’ve seen in other regions and apply it, but we all know that the temperatures can fluctuate here and we have very different temperatures and relative humidities than other regions.
Organic Fertility and the Nitrogen Cycle
The Fertility Information Gap
Organic fertility is really my specialty. Organic fertility is challenging in any system, and we have very limited information for cuts as Celeste and Natalie were talking about. Okay, so again, here’s this University of Maryland Extension document, which is so helpful, but we are lacking information on how much fertility to apply to cut flowers. And we’re excited to hear what Tennessee is finding and what we’re finding in some of my trials. I often wonder if in cut flower production we could be under-fertilizing. This is especially true in organic production. Okay.
How Organic Nitrogen Becomes Available
All right, why is it harder in organic production? And I’m going to talk about the nitrogen cycle, which sometimes causes people to shut down, but stay with me because it’s a wonderful process that helps become these nutrients become available. All right. So organic nitrogen is in a complex form, right? It’s poultry manure, it’s compost, it’s feather meal, right? And they’re these big amino acids, they’re carbon chains. And we’re really required on mineralization, which is done by microorganisms in the soil to break it down to plant available ammonium. All right, ammonium then undergoes nitrification and then it becomes plant available nitrate. Again, a microbial mediated process.
All right, so both of these can be taken up by the plant, right? But they can also be lost from the system. One way they’re lost from the system is through immobilization. That’s where our microbes in the soil compete with our plants for the available nitrogen. We can have nitrate leaching, which is where rain or irrigation pushes the nitrogen outside of the root zone. And we can have ammonia volatilization, which is where we have the gaseous loss of ammonia from the soil to the atmosphere. Right, so when we’re trying to figure out how much organic nitrogen becomes available from these fertilizers, we’re having to think about the rate of mineralization, the rate of nitrification, immobilization, and leaching, which as you can imagine is really complex and hard to predict.
Okay, so I’m going to talk more about fertility when I get to the sunflower section. So I just wanted to introduce that here, but first I’m going to talk about our snapdragon trials.
Trial One: High Tunnel Versus Field
Design and Rating Scale
Okay, so a lot of our small and mid-sized growers have both high tunnels and field production. We know that snaps are pretty hardy. I’ve actually been really impressed with their ability to withstand the weather that we had this year. We were seeing 20 Fahrenheit ice storms and snow, and they did a great job even in our field. But we wanted to see how the high tunnels impact snapdragon quality and harvest windows. All right, so we did this with a December 1 plant date, and we did it with two different cultivars, one being Madame Butterfly Bronze with White. And two being Chantilly Bronze. Okay? And here you can see my field trial versus my high tunnel trial. Each plot had about a hundred plants in it, and we replicated it over four times. And so here’s that Madame Butterfly Bronze with White and Chantilly Bronze, both two beautiful cultivars that we got to work with.
And this is our rating scale. So I’m going to come back to this, but I want you to notice we’re going from 1 to 10. When we’re taking into account quality and rating, we’re looking at how long that stem is. We’re looking at how long that inflorescence is, right? How much of that actual flower is. And then we’re also trying to look at density. Okay. So are those flowers spread down the stem, or are we seeing a large flower with compact flowers, right? The higher the quality, the better we can do selling it at the market.
Results: Harvest Timing and Duration
Okay, going into results, what I want to highlight here is looking at we have our flowers, our Chantilly here. Madame Butterfly on the bottom. Then we have our field versus high tunnel production, field versus high tunnel production, our first harvest. our last harvest, our harvest duration, the quality, stem length, flower height, spike height, and density. Again, that’s how well are these flowers kind of filling out that stem. All right, what I wanted to show you with this is it was very interesting to me that for our field versus high tunnel studies for both cultivars. We did not see a difference in that first harvest, right? It makes sense is that flower is not driven just by temperature, but it’s also driven by light. But I was really surprised that we had the same first harvest date for both Field and high tunnel. And notice we had about a week difference between that Chantilly and that Madame Butterfly in our study. Our last harvest again was very different between the field and the high tunnel. All right.
So if we look at this looking at harvest duration, how long was I picking on those flowers, right? For Chantilly in the field, we had a harvest duration of about 15 days, about two weeks. You contrast that to the high tunnel, I had a harvest duration of about eight days. Similarly for Madame Butterfly, we had about two weeks in the field, more than ten days when we came to the high tunnel. So if you’re looking more for a more rapid, uniform harvest a high tunnel might be a way to go. If you’re trying to stretch out that harvest, you might be able to do that via a field. We didn’t see big differences in quality between the two, which I was really surprised about. But a lot of this had to do with our density, which I’m going to get into that after I do stem length.
Stem Length and Density
We did see big differences in our stem length. And this is a very crucial point depending on who your market is. All right, so in our field we saw about 10 centimeters shorter stems than we did in our high tunnel. That’s about four inches, right? So that’s a pretty big difference in stem length. So if stem length is really important to your buyers, high tunnel production might be important to that. All right, but this density indicator.
So something that I noticed was that in our high tunnels we started to get those flowers being stretched out over that flower stem. So even though we were getting good quality long stem length. Especially in our Chantillys, we have a little bit of those flowers going down the bottom of the stem and having a less dense spike. I think most of this was due to our really bizarre winter this year. If y’all remember, we had February’s in the 80s going back and forth between 20 degrees. And I think that these high temperatures in the high tunnels exasperated that flower moving down into the stem and reducing density.
High Tunnel Versus Field Takeaways
All right, so what are our high tunnel versus field takeaways? In the high tunnel, we saw more intense and shorter harvest, right? So kind of them all being ready more uniformly. We had no difference really in the first flower timing, which was surprising. High tunnels increased stem length in both cultivars by about 10 centimeters or four inches. And we saw some density issues, right? And I do think that the high tunnel could have exasperated this density issue. So it’s something to think about with these more unusual temperature fluctuations that are becoming more usual, right? Balancing who you’re buying for and what their market is might help you make that decision between the high tunnel and field. Just on a side note. I spent quite a bit of time covering my snaps this year. I probably could have gotten away with it, but I will say the high tunnel saved me a lot of time in that regard.
Trial Two: Plant Date and Eight Cultivars
Design and Fertility Rates
Moving on to my snapdragon and plant date study, we did this with Johnny’s and in this one we wanted to figure out like how does plant date impact both flower quality and also flower harvest. Okay, so we did this with two different plant dates. We did a January 7th plant date and a March 11th plant date. So two plant dates about two months apart. Okay. I did use my organic fertilizer and I just wanted to share these rates with you because they might seem high, but again, I think for organic fertilizers we really need to be thinking about how nitrogen becomes available. So I put out 100 pounds of nitrogen at planting, and then I side-dressed 50 pounds of nitrogen about halfway through the growing season. I also put out a good bit of potassium. In our southern soils, potassium can leach quickly, and so I wanted to make sure that we had good flower set and bloom. And I did that with potash, okay? So remember, organic, so not all of the fertilizers are available immediately. We’re releasing it over time. A different rate of release than when we think about conventional fertilizers. All right, and here you can see our field study with eight different cultivars. Okay, and these are commonly grown cultivars, but also ones that Johnny was interested in seeing growing in our southern region.
The Eight Cultivars
All right, so I’m going to go through what some of these flowers look like and then talk to you about some of the quality attributes. All right, so the first one is Antibes Apricot I. It’s a group one and it’s not particularly recommended for our summer. It’s not particularly recommended for summer production. So it made sense for that January plant date. I love this flower. It had a beautiful plump flower, nice coloring. I will say the stems are short, and I’ll show you that data at the end.
Then we had an Avignon Lavender 2, which you can see here on the right. It’s a group 2 snapdragon. It had a beautiful color and had a wonderful scent as well. And we had stems around 50 centimeters for this one and a staggered harvest.
Next we had Avignon Apricot. Now this was probably my favorite and I think I just like the butter yellow. It was a lot yellower than what I had seen in seed catalogs, but it was a really gorgeous color. Again, shorter stems though. Balancing, what is this market for? Who are you growing this for? And you can see we had a little bit of that kind of undesirable kind of flopping we get with snaps when those stems aren’t quite as strong.
Next we had Potomac Orange. Potomac Orange was a group three or four snapdragon. That harvest window was a lot later for this one. But it had a very vibrant color, it had a good, strong stem, and it seemed to have a very long vase life in my not scientific studies, but it’s one that really hung around.
Next we did Chantilly Light Salmon. And this was just like a nice go-to snapdragon. I was really impressed with like how many stems I was able to get for it from it. And it also continuously harvested throughout the year. It almost has like a stock-like bloom and a ton of stems per plant and just a hardy kind of uniform flowering time.
Next we had Cannes Light Bronze, a beautiful color, good stem length, good stem height. It was about 60 to 65 centimeters. And the harvest is a little bit more stretched out, but overall another great selection.
Potomac Lavender here on our left, it did okay. Something I want to note is it had a little bit of a later flowering date in our region. It’s a group three or four snapdragon. And you can see here on these stems what I was talking about. We get that flower up at the top, it’s not fully full. So maybe not the best for the plant date that I chose. Sometimes it did have fragrant. Sorry, it was very fragrant, and then sometimes it had bigger stems.
Same for Costa Summer. It had very strong stems. You can see it had a nice flower development. It was super tall, 65 to 70 centimeters. And I actually liked that it opened into a much lighter color. It had a very beautiful gradient as it hung out in the stem.
Plant Date Results and Stems Per Plant
All right, so wrapping this up, what did I find in the snapdragon plant date trial? Here on the top, we have our first plant date. Remember January 7th? Then we have our second plant date, March 11th, and then all of our cultivars. Okay? What I want to highlight here is this 50% of the plot. harvestable or mature. So here you can see we started harvesting kind of around late April for our first plant date, we were closer to May. Okay. But what I want to highlight again, these were 60 days apart. Our harvest windows are not 60 days apart, right? So remember, as you’re doing succession planting, we have to think about growing degree days and light as well. Okay.
Another thing that we found really interesting was the harvest per plant, this column right here in the middle. And what that means was how many stems did I get per plant that I planted? Something I found really interesting was for this first plant date, we were more like two stems per plant, which these were pinched, so I was expecting a little bit more branching. In that second plant date in March, we were getting closer to three to four. So it was a shorter window, but they were ready and there were more stems per plant. Overall, I don’t think I saw a huge difference in bloom quality between the two plant dates. Stem length was fairly consistent with higher stems with longer stems being in that second plant date, and then overall rating was similar between the two plant dates.
Takeaways, Year Two, and Contact
All right, so takeaways for that snapdragon and plant date. Thinking about planting two months apart. Remember you’re not going to get that harvest. two months apart. So think about how you’re going to do succession planting, whether that’s with plant date or with cultivar. We did have some stem thickness issues, especially with that second plant date. Just a few of them were just a little bit too fat, maybe for a lot of our florists. We had more stems per plot and our second plant date. And I’m working on the second year. So I will repeat both the high tunnel and the snapdragon next year. And that’ll really allow me to hone in on how weather drives some of these quality aspects and flowering time for our snapdragons here in the South.
This was my first time growing snaps for a cut flower production and I just want to say I was really impressed With all of these cultivars about how hardy they were. They just really took it kind of the dynamic weather that we had this season and really did well. All right, so come back to me for that second part, I think after around the 11, looking at lisianthus and sunflowers. And as always, I want to thank American Takii and Johnny Seeds. My email’s at the bottom, I would love to talk to any growers anytime about problems they’re seeing, especially if you’re in organic production. And Natalie and Celeste mentioned this. We have the ability to mess around when you guys don’t. So please let us know your questions and how we can help with this growing. All right, thank you. And I’ll be glad to take questions.
Questions and Answers
Seeding Potomac Now for a Fall Bloom
Gabrielle LaTora: Thank you, Dr. Cassity-Duffey. Can you hear me this time? Okay, good. We have one question for you. Would snapdragons started from seed now bloom in late fall? And this is Potomac specifically.
Kate Cassity-Duffey: Yeah. So that is an excellent question and one I have myself. I do know that some growers are doing that. I’m going to start one in August and see what that is. With Potomac, I think you should be able to seed now. I’m finding about 10 weeks from seed until transplant. And then I would imagine hopefully, but it will be light specific. You’ll have it by fall. And I think the Potomac’s a group one. So following those groups is really important. But yeah.
At 18:05 the speaker gives Potomac as a group one. A participant corrects this in the chat at 19:43 and she accepts the correction on air, below. Her cultivar walk at 12:53 and 13:57 gives Potomac Orange and Potomac Lavender as group three or four.
Same Cultivars in Year Two
Gabrielle LaTora: Perfect. Thank you. One more question. Will your second year study cover the same cultivars or will you drop and add?
Kate Cassity-Duffey: Yeah. I will do the same cultivars. so that we can see how the cultivars might respond to different weather. So then I can more like hone in onto the weather. If you have any cultivars that you think are interesting, please let me know or ones that you think are doing really well in the South and I could add some.
Spacing and Rows Per Bed
Gabrielle LaTora: Perfect. Okay, we got another one coming in. How far apart are your spacing for your snapdragons and how many rows per bed?
Block 279 runs four turns inside 7.8 seconds and is not split. The turn changes are placed inside the paragraph.
Kate Cassity-Duffey: Yeah, this one I did on a four inch spacing a little bit closer and so… four inch spacing and then I did four rows per plot on three foot centers. I’m trying to make sure. Unidentified participant, off mic: Yes. Kate Cassity-Duffey: Yes. That’s what I did. Yeah. Gabrielle LaTora: Perfect. Okay, one more.
What the Snapdragon Groups Mean
Gabrielle LaTora: Can you just cover briefly what the different classes mean on snaps as far as early or late?
Kate Cassity-Duffey: Yeah. So group one, group two, group three, group four, right? It’s something I’ve been learning transitioning from vegetables to cut flower production because it’s very different. In group one and group two, it’s giving you an indice of when they might perform the best and that flowering time. So for instance, group ones are typically cooler, faster, and your group twos and threes are a little bit longer. I’ve also noticed there are quite a few kind of groupless.
Gabrielle LaTora: Okay, cool. Thank you.
Kate Cassity-Duffey: Typically it’s a three to four. Oh, I’m surprised by that from Florida. That’s interesting. Thank you. I saw that chat.
Groups three, Madame Butterfly is a groupless one and so she does what she wants. The thing about groups is they’re giving us an indice on time to flowering. They also help us understand stem length like in lisianthus as we get into higher groups we tend to get longer stems due to the longer growing time and you can stagger with group one and two so like you’re going from cool to longer seasons.
Gabrielle LaTora: Great, thank you so much, Dr. Cassity-Duffey. We appreciate you
Transcript processed for UGA Center for Urban Agriculture / Cut Flower Symposium Archives
Source: Corrected SRT (Stage 1), GTBOP_Transcript_2026-07-23_CassityDuffeySnapdragons.srt (301 blocks)