Bold new cultivars of familiar plants are born at Sandhills Research Station and other testbed fields and gardens statewide.

by Corbie Hill

Photography by Mollie Tobias

A tiny tree stands in a row with its larger brothers and sisters.

It’s shorter than most toddlers, but perfectly formed. Its twig-thick branches zig and zag geometrically, and it boasts the mature, fleshed-out architecture of a tree ten times its height. If anything, it looks like a carefully trained bonsai, but it is not. This is a dwarf redbud, and it’s three years old.

Denny Werner pauses to admire this tiny tree. He knows a great deal about this specimen – its hardiness, its bloom characteristics and leaf shape, its genetics — yet he marvels at its size and form, its color and geometry, as if seeing it for the first time.

“That’s a very special tree, right there. That’s a real winner,” Werner says. “He’s going to get selected.”

If that happens, within a few years descendants of this patio-sized redbud will join Werner’s other hybrids that have entered the commercial gardening world. He can walk into plant nurseries or even the garden sections of big box retailers and spot plants he’s bred. In Werner’s four decades with NC State University, where he is a distinguished professor in the Department of Horticultural Science, he has bred peaches and butterfly bushes. His main focus nowadays is redbuds. 

Yet Werner is only one of many plant breeders in North Carolina, a historically agrarian state which continues to be at the forefront of crop science, ornamental plant breeding and a constellation of horticultural subfields. To provide a little perspective, the patio-sized redbud that has so captured his attention is only one plant on the 500-plus acre Sandhills Research Station in rural Montgomery County. Elsewhere on this enormous experimental farm grow yet-unpatented varieties of soybeans, blueberries, cotton, peanuts – you name it – and that’s only the beginning. NC State operates other research stations statewide, including one not far from Asheville. Elsewhere and separately, entrepreneurial breeders like Tony Avent of Raleigh’s Plant Delights Nursery regularly introduce bold new hybrids to the ornamental plant industry.

Indeed, horticulture has a deep history in North Carolina, and a vibrant present and future as well. As a horticulturalist and breeder with NC State University, Werner is at the cutting edge. And even though he’ll formally retire only a few weeks after this story prints, he’s nowhere near quitting.

“You get momentum in an area and a body wants to keep on moving,” Werner says. 

He’s talking about plant breeding in North Carolina, but he could just as easily be talking about his own inertia. He has redbuds with pink pompom flowers growing next to experimental lines with double flowers that bloom white (“There’s no such thing as a double white redbud anywhere except right here in this row,” he says). He’s worked on a purple leaf weeping form called Ruby Falls, which has been a commercial success, and he’s currently working to bring gold leaves into a weeping redbud. He’s creating drought-tolerant dwarf varieties, purple dwarfs, purple weeping dwarfs – the list goes on and on. Werner is even working on a redbud that actually blooms red.

Upon his retirement this summer, Werner will simply move his base of operations from the Sandhills Research Station to the JC Raulston Arboretum (JCRA) in Raleigh, which also operates under the aegis of NC State University. 

“It would be nice to have a place I can call home,” says Werner. “One of the reasons I initially began working with redbuds is because of the great collection the arboretum had when J.C. Raulston was director.” Raulston, an influential and beloved NCSU professor and horticulturalist, founded the arboretum as the N.C. State University Arboretum in 1976, and Werner arrived in 1979. After Raulston’s 1996 death, the arboretum’s name was changed in his honor.

“I didn’t get to see the arboretum get born, but I saw it in diapers,” Werner says. “I remember walking through the arboretum with J.C. and talking about redbuds, and it got me to breeding things. Full circle, I’d like to get redbud breeding back into the arboretum umbrella.” Werner was even JCRA director for three years, and during this tenure he hired Mark Weathington as assistant director. Today, Weathington is arboretum director, and he’s thrilled to have Werner back.

“We really hope this will be the start of a long-term formal breeding program at the arboretum,” Weathington says, sitting in his airy office at the Raleigh arboretum. “We’re surrounded by so many plants. We have this great repository of germplasm, of different genetics from plants. That gives us a lot of opportunity to do exciting things.” 

JCRA has not traditionally had an active breeding program, Weathington explains. Sure, the arboretum has introduced a number of plants, but mostly these were varieties it evaluated rather than developed. Sometimes, too, something unusual grew from seeds sown on JCRA grounds, so the arboretum named and distributed it, but none of this constitutes the kind of diligent, formal breeding program Werner oversees.

“I thought it would be good for both entities, myself and the arboretum, to more or less weave my activities under the umbrella of the arboretum,” says Werner. “When we release new varieties, we can release them as JC Raulston Arboretum releases, which will give them somewhat of an identity in the marketplace and it’ll give the arboretum an identity as an entity that is developing new plants and is involved in research.”

 

Avent of Plant Delights Nursery grows in sand, Weathington offers, and has been very successful. Avent breeds elephant ears with a colleague in Hawaii and also develops lilies, Baptisia, epidemiums, woody plants and even ferns. (“He has explained to me how he does it and I am not sure I understand it,” Weathington says of the fern hybrids.) Like many of the breeders Weathington mentions, Avent has very high standards. “If it isn’t superior to everything that’s out there, even if it’s different, it doesn’t make its way into the market,” Weathington says.

 

This will add to an already strong reputation, as breeders nationally and internationally already send plants to JCRA for evaluation. NCSU is one of the leading plant breeding institutions in the world, Weathington says, and the climate in North Carolina itself is amenable to growing a variety of plants. Anything that grows north of the subtropics will grow here and can be evaluated here, Weathington says – even if the soil isn’t amazing. But that can be fixed, Weathington adds.

“Organic matter is the magic bullet. You add it to clay, it provides drainage. You add it to sand, it holds water,” he says. “If I had my choice of what to garden on, it would be sand. It’s pretty easy to amend that, to put organic matter in there and build up that soil. I’d rather have more drainage than less.”

 

At NCSU, breeders develop new varieties of cucumbers, but only a minority of these cultivars are destined to be eaten raw. Rather, they’re bred to fit in pickle jars. They must mature to a small size and have thin skin and the proper texture. Melon breeders from the university travel the world to collect the original species that were crossed to create now-familiar food crops. Their aim to bring these wild species’ disease resistance to their cultivated cousins.

Just south of Asheville, the Mountain Horticultural Crops Research and Extension Center in Mills River has responded to North Carolina’s brewery boom by breeding new varieties of hops, Weathington says, and also trees, shrubs and biofuel grasses under the direction of NCSU’s Tom Ranney.

“To do a list of the plants from him would be almost exhaustive,” Weathington says of the award-winning breeder. 

Ranney and Werner’s approaches are almost diametrically opposite, Weathington says with a smile. Werner is laser-focused on a few varieties at once, while Ranney is extremely prolific and works on dozens of genera at a time.

“I always try to stump [Ranney],” Weathington says. “I say, ‘You know, you should breed these obscure plants.’ And he’ll go, ‘Oh! I think two rows over we have third generation of crosses from that.’ 

“It’s amazing working with both of them,” he continues. “They’re both very effective.” 

Back at the Sandhills Research Station, Werner walks his rows. True to Weathington’s description, he’s looking for one thing – for that one perfect dwarf purple redbud, say, or that one perfect double white redbud that will spawn an entirely new cultivar – when he comes across a skinny, leafless tree and stops. Analytically, but also with unmistakable tenderness, he reaches out. He takes the end of a branch in between his fingers and snaps it.

“They’ve had a rough winter down here,” he says. “Rough, rough year.”

 

 

Of all the trees on this row, this one couldn’t handle the additional below-freezing days this winter brought to bear. That’s the bad news and the good news, Werner explains. If we hadn’t had such a harsh winter, he wouldn’t have known that this one specific plant was less cold-resistant than its brothers and sisters – and he could have inadvertently released a plant that wouldn’t thrive in the Midwest.

And it’s too quiet, Werner observes a little later. There are some bees out, but not as many as he would have seen 10 or 15 years ago. Redbuds are dependent on bumblebees and carpenter bees, as well as other native pollinators. Bumblebees nest in the ground and there is a forest nearby – prime habitat – yet their numbers have simply crashed.

It’s an ecological problem for sure, and it also means that Werner must do the bees’ job. So he digs the trees upevery winter, moves them into a greenhouse and pollinates them manually. Once a body has momentum, as he says, it wants to keep moving.

“In this business, if you’re unsuccessful, you have to wait another year to try again,” Werner says. “And I’m not getting any younger.”