1,200 hibiscus seedlings went in the ground. Seven came out. 🌺
S02:E09
John Ruter put 1,200 hibiscus seedlings in the ground and kept seven. The other 1,193 got bush hogged. He is the Armitage Professor of Horticulture at the University of Georgia and the director of the UGA Trial Gardens, and this week he walks Ping through everything that happens between a cross and a plant you can actually buy. It takes ten to fifteen years, and in his case it started with a phone call from a mountain research station.
The superintendent at Blairsville told him to come up and look at his hibiscus. When John got there the plants were covered in hibiscus sawfly, which runs four generations a year in Georgia. His answer came from a native species with hairy leaves. Under the microscope, Hibiscus grandiflorus looked like old shag carpet, and it had zero feeding damage. Moving that hairiness into his red-leaved selections cost him an F2 and a backcross and several years, and it produced the first hardy hibiscus ever released with sawfly resistance. Five of those plants became the Head Over Heels series.
There is a lot here beyond hibiscus. John explains why an Asian species and an American species usually will not make a fertile hybrid, using a dance-floor image that lands in one sentence. He explains why hardy hibiscus cannot be propagated offshore like almost everything else in the trade, why every cultivar he releases starts with the letters RUT, and what he does with graduate students that put three of them in first, second and third place at the same symposium. Ping brings her own hibiscus story too, from Chengdu, where Hibiscus mutabilis is the city flower.
Listen Time: 52:28 Follow Along with the Transcript
Dr. John Ruter, Armitage Professor of Horticulture, University of Georgia, and Director of the UGA Trial Gardens. He teaches three courses and runs an ornamental plant breeding program covering both herbaceous and woody plants. Past and current work includes hibiscus, Ilex, camellias, conifers, Salvia, Pycnanthemum and Lagerstroemia. His first release, the holly Emerald Colonnade, is now used as a boxwood replacement on estates.
Host: Dr. Ping Yu, UGA Department of Horticulture
“And we ended up picking seven out of 1,200 to keep.” Dr. John Ruter (15:00)
“it looked like old shag carpet growing on the leaves, and we noticed that they had zero damage” Dr. John Ruter, on the trichomes of Hibiscus grandiflorus (16:30)
“The hybrid ends up with three sets of chromosomes and somebody doesn’t have a dance partner.” Dr. John Ruter, on triploid sterility (27:00)
“So it’s always a number game.” Dr. Ping Yu (18:42)
“I don’t baby them, I don’t hold their hand, I don’t call them every day and say this is what you’re doing today.” Dr. John Ruter, on advising graduate students (46:31)
Hibiscus sawfly. A Hymenoptera insect, so it sits in the bee family. The larvae are what chew the foliage. The adults look like a little black fly with a red orange thorax. Georgia gets four generations a year, which is why it turns into a real production problem rather than a nuisance.
Trichomes. Plant hairs. Hibiscus grandiflorus is loaded with them, and that physical barrier is what gives it complete sawfly resistance. Breeding the trait in has a visible cost: the trichomes shift the red foliage toward a matte red-gray rather than a glossy red.
Lodging. John gives the definition himself. It is an agronomic term for falling over, and it was one of the original flaws he set out to fix in the hardy hibiscus of the late 2000s, alongside late spring emergence.
Heterosis. Also called hybrid vigor. His mutabilis by taiwanensis F1 hybrids hit ten to twelve feet in a single season, which is the effect working exactly as advertised and also more plant than any nurseryman wanted.
Ploidy, and why crosses fail. The hardy hibiscus native to the eastern United States are diploids, two sets of chromosomes. The Asian species, including Hibiscus mutabilis, taiwanensis and Hibiscus syriacus, the Rose of Sharon, are generally tetraploids with four sets, and their base chromosome number is different too. Cross a diploid with a tetraploid and the offspring gets three sets. One set has nothing to pair with at meiosis, and the plant is sterile. John compares such a hybrid to a mule.
Cultivar name versus marketing name. The cultivar name is the permanent botanical identifier and it is often deliberately nonsensical, which is why UGA settled on the RUT prefix for everything out of John’s program. The trademark or marketing name is what appears on the pot, and in the last ten to fifteen years the companies have wanted to choose that themselves, along with the series name.
The one-year patent clock. In the United States, a public disclosure that reads as an offer for sale starts a twelve-month window to file a plant patent. That is why an unreleased selection photographed on a garden tour, or printed in a catalog by accident, becomes an urgent filing rather than a minor problem.
Mountain mint. John’s program holds 16 or 17 of the 19 native Pycnanthemum species and has just finished a four-year garden trial. Only two named cultivars exist. It is a strong pollinator plant, and the species are distinct enough that you can often tell them apart by the scent of the foliage.
Blooms and Beyond explores plant history, culture, and management through the lens of science. Whether you’re a commercial grower seeking practical solutions, a student exploring careers in horticulture, or simply someone who loves plants and their stories, there’s something here for you. Hosted by Dr. Ping Yu of the University of Georgia, each episode features interviews with experts who share enchanting stories, cutting-edge research, and practical wisdom from the world of horticulture.
Your benefit: After each episode, commercial growers will have at least one useful tip for their operation, and plant enthusiasts will have an interesting fact to share. That’s how we spread plant power to more people and make our environment a little better.
Host: Dr. Ping Yu Producer: Rich Braman Guest: Dr. John Ruter, Armitage Professor of Horticulture, University of Georgia; Director of the UGA Trial Gardens
Episode Release Date: August 30th, 2026 Episode Length: 52:28
“Till next time, stay healthy and go plants!” 🌱
