Segment Title: Organic Snapdragon Production: High Tunnel and Plant Date Trials
Segment: 04 of 08
Webinar Date: July 23, 2026
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 (1218.516 s, measured)
Series: Cut Flower Symposium
CEU Categories: [PENDING]
NARRATIVE SUMMARY
Kate Cassity-Duffey opens by telling the room this is part one of her talk, moved up because of technical issues, and that she will cover snapdragons rather than the sunflowers and lisianthus her recorded introduction has just promised. She is a soil scientist by training who reached cut flowers through organic vegetable growers, many of whom now grow flowers as a value-added product beside CSA shares and farmers market sales.
Two problems frame the work. Field production in the South shortens stems and leaves damaged or tattered flowers, against a commercial grade of roughly 60 centimeters for most cut flowers. Organic fertility is the harder problem, and it is her specialty. Nitrogen arrives as poultry manure, compost, or feather meal and has to pass through mineralization and then nitrification before a plant can take it up, while immobilization, nitrate leaching, and ammonia volatilization remove some along the way. A University of Maryland Extension document is the only fertility guidance she names, and she says outright that cut flower growers may be under-fertilizing.
The first trial sets a high tunnel against the field on a December 1 plant date, using Madame Butterfly Bronze with White and Chantilly Bronze, about a hundred plants per plot replicated four times. First harvest date did not differ between the two, which surprised her, since flowering answers to light as well as temperature. Nearly everything after that did. Chantilly ran about 15 days of harvest in the field against eight in the tunnel, Madame Butterfly about two weeks against ten days, and tunnel stems came in about 10 centimeters longer for both cultivars. The tunnel also loosened the spikes, with flowers spreading down the stem, which she ties to a winter that swung between the 80s and 20 degrees.
The second trial puts a January 7 plant date against March 11 across eight Johnny’s cultivars, fertilized at 100 pounds of nitrogen at planting plus 50 side-dressed at midseason, with potassium as potash because southern soils leach it quickly. Sixty days between plantings did not buy 60 days between harvests. The March date gave three to four stems per plant against two, though a few stems ran thick enough to bother a florist. Four chat questions close the segment.
CHAPTER TIMESTAMPS
0:00 Introduction and Recorded Bio
0:36 Part One, and Why Snapdragons
1:32 Why Organic Growers Are Adding Cut Flowers
2:12 High Tunnel or Field, and Why the South Is Hard
3:20 Organic Fertility and the Maryland Gap
3:53 The Nitrogen Cycle, and Why Organic Is Harder
5:28 Trial One: High Tunnel Versus Field, and the Rating Scale
6:48 Results: Same First Harvest, Different Last
8:01 Harvest Duration: Fifteen Days Against Eight
8:40 Stem Length, Density, and a Strange Winter
9:41 High Tunnel Versus Field Takeaways
10:30 Trial Two: Two Plant Dates, and the Fertilizer Rates
11:47 The Eight Cultivars, One by One
13:48 Potomac Lavender and Costa Summer
14:34 Plant Date Results and Stems Per Plant
15:57 Takeaways, Year Two, and Contact
17:24 Q&A: Seeding Potomac Now for a Fall Bloom
18:11 Q&A: Same Cultivars in Year Two
18:37 Q&A: Spacing and Rows Per Bed
19:07 Q&A: What the Snapdragon Groups Mean
QUESTIONS & ANSWERS
Q: Why is this talk about snapdragons when the program lists sunflowers and lisianthus?
A: Cassity-Duffey says at 0:42 that technical issues moved her up and she is giving part one of her presentation. She asks the audience to come back to her for the second part, on lisianthus and sunflowers, “after around the 11.” That second part does not appear on this recording.
Q: Why is organic fertility harder to manage than conventional fertility?
A: Organic nitrogen arrives in a complex form, as poultry manure, compost, or feather meal, built of large amino acids and carbon chains. It depends on mineralization by soil microorganisms to break down into plant-available ammonium, and then on nitrification to become plant-available nitrate. Both are microbially mediated. At the same time the system loses nitrogen three ways: immobilization, where soil microbes compete with the crop for what is available; nitrate leaching, where rain or irrigation pushes it below the root zone; and ammonia volatilization, the gaseous loss from soil to atmosphere. Predicting how much becomes available means predicting all five processes at once.
Q: Did the high tunnel move the first harvest date?
A: No, and she says she was really surprised by that. The trial ran a December 1 plant date with Madame Butterfly Bronze with White and Chantilly Bronze, about a hundred plants per plot replicated four times, rated 1 to 10 on stem length, inflorescence length, and density. Both cultivars hit the same first harvest date in the field and in the tunnel. She reasons that flowering is not driven by temperature alone but by light as well. She does note about a week’s difference in first harvest between Chantilly and Madame Butterfly.
Q: How much did the high tunnel shorten the harvest window?
A: For Chantilly, about 15 days of harvest in the field against about eight days in the high tunnel. For Madame Butterfly, about two weeks in the field against more than ten days in the tunnel. Her framing: a high tunnel suits a grower who wants a rapid, uniform harvest, and the field suits one who wants the harvest stretched out.
Q: What happened to stem length, and what did the tunnel cost in exchange?
A: Field stems ran about 10 centimeters shorter than high tunnel stems, about four inches, in both cultivars, and she calls stem length the point that depends on who your market is. The tunnel charged for it in density. Flowers began stretching out along the stem rather than sitting compactly, so even with good quality and long stems, especially in the Chantillys, some ran down toward the bottom and the spike was less dense. She attributes most of that to a winter that put February in the 80s and swung back to 20 degrees, and thinks high temperatures in the tunnel worsened it.
Q: What fertility went on the plant date trial, and why do the rates look high?
A: 100 pounds of nitrogen at planting, then 50 pounds side-dressed about halfway through the growing season, plus a good bit of potassium as potash because potassium leaches quickly in southern soils. She flags the rates as possibly seeming high and explains that organic fertilizer releases over time at a different rate than conventional, so not all of it is available immediately.
Q: Which cultivars had short stems and which had long ones?
A: On the short side, Antibes Apricot I, which she liked for its plump flower and coloring, and Avignon Apricot, her favorite for its butter yellow, both of which she calls out for shorter stems and for the flopping that follows when stems are not strong. Avignon Lavender 2 ran around 50 centimeters. On the long side, Cannes Light Bronze at about 60 to 65 centimeters and Costa Summer at 65 to 70 centimeters with very strong stems. Potomac Orange had a good strong stem and what she describes as a very long vase life in her not-scientific observation.
Q: Did planting two months apart give harvests two months apart?
A: No. She underlines that the plant dates were 60 days apart while the harvest windows were not, and tells growers doing succession planting to think about growing degree days and light rather than calendar spacing alone. Harvest for the first plant date started around late April, with the second closer to May.
Q: How many stems per plant did each plant date give?
A: The January plant date came in at about two stems per plant, which she found interesting because those plants were pinched and she expected more branching. The March plant date ran closer to three to four. Her summary is a shorter window on the later date, but more stems per plant. Bloom quality did not differ much between the two, and overall rating was similar; stem length was fairly consistent, with the longer stems on the second plant date.
Q: Can snapdragons started from seed now bloom in late fall, specifically Potomac?
A: She calls it an excellent question and one she has herself, and says she knows some growers are doing it and that she will start one in August to find out. Her estimate is about 10 weeks from seed until transplant, and with light being the deciding factor she would imagine a fall bloom. She adds that following the groups matters, and says she thinks Potomac is a group one. A participant then corrects this in the chat at 19:43, giving Potomac as typically a three to four, and she accepts the correction on air. Her own cultivar walk puts Potomac Orange and Potomac Lavender in group three or four.
Q: How were the snapdragons spaced?
A: Four inch spacing, which she describes as a little bit closer, with four rows per plot on three foot centers.
Q: What do the snapdragon groups mean?
A: The groups give an index of when a cultivar performs best and of flowering time. Group ones are typically cooler and faster; group twos and threes run a little longer. She has also noticed cultivars described as groupless, and names Madame Butterfly as one, saying she does what she wants. In lisianthus, she adds, higher groups tend to give longer stems because of the longer growing time, and a grower can stagger group one against group two to move from cool into longer seasons.
ADDITIONAL RESOURCES
Named on camera by the speaker:
- University of Maryland Extension document on cut flowers, which she calls up at 3:30 as helpful but silent on how much fertility to apply. No title or web address is spoken.
- Johnny’s, the seed source for the eight-cultivar plant date trial. She says at 11:40 that the cultivars are commonly grown ones plus ones Johnny was interested in seeing grown in the southern region.
- American Takii, thanked alongside Johnny’s Seeds at 17:00.
- Her email address, which she says at 17:03 is “at the bottom” of the slide and invites growers to use anytime, especially organic producers. No address is spoken on the recording, so it has to be supplied by the speaker or the symposium organizers before publication.
SOURCE NOTES
This is a full-track segment at 20:18.5 and the standard Stage 2 targets applied without light-track scaling. Four things about the source shaped the file.
The title is built from the body, not the agenda. The printed agenda and her own recorded bio both promise field-grown sunflowers and lisianthus. She delivers neither. Her line at 16:52 asking the audience to come back “after around the 11” refers to a slot that Bikash Ghimire took, so the second part was never delivered and no part two exists to link.
Chapter density is one marker every 61 seconds, 20 across 20:18. That is denser than one every 3 to 5 minutes and slightly denser than segment 03’s one per 80 seconds, because the middle of the talk walks eight cultivars in under three minutes and the last three minutes carry four separate chat questions. Every marker was checked by script against a block start time in the corrected transcript. The closest pair, 18:11 to 18:37, is 26 seconds apart and clear of YouTube’s 10 second minimum. The last marker is 1:11 before the end.
One claim in the Q&A is a live self-correction and is presented as one. At 18:05 she says she thinks Potomac is a group one. At 19:43 she reads a chat message giving it as typically a three to four, says she is surprised, and thanks the participant. Her own cultivar walk at 12:53 and 13:57 puts Potomac Orange and Potomac Lavender in group three or four. No statement in this file asserts that Potomac is a group one. The Q&A pair carries the exchange instead, which is the only reading the recording supports.
One numeral is inconsistent between two cultivar names, by design. Block 159 reads “Antibes Apricot I” and block 166 reads “Avignon Lavender 2.” The Roman numeral was confirmed against the recording in the sweep; the arabic one was never flagged and both engines rendered it as a digit. The transcript stands as verified rather than being normalized on inference. Quote each as the SRT has it.
Zero open flags. All ten [VERIFY] markers raised at merge were closed against the recording on 2026-08-10, before any derived file existed. Three resolutions are load bearing here: Antibes Apricot I and Cannes Light Bronze are both cultivar names in the eight-cultivar walk, and “harvestable or mature” at 14:51 is the column definition behind the plant date results.
Verification, run from _Verify/ on the corrected SRT before writing:
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verdict PASS
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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)