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New hardy rose variety was 16 years in the making

Cherry Frost blooms in cycles from early July through October. Photo courtesy of Julie Overom.1 / 5
Local master gardener Julie Overom leads a breakout session on propagating roses during the Spring Gardening Extravaganza at the First United Methodist Church in Duluth. Clint Austin / Forum News Service2 / 5
A cluster of Cherry Frost flowers in different stages of opening, contribute to its continuous blooming habit. Photo courtesy of Julie Overom.3 / 5
The Cherry Frost shrub rose has a round shape with gently arched stems. Over time, it can get 5 or 6 feet tall with no need for staking. Photo courtesy of Julie Overom.4 / 5
Cherry Frost flowers are 2 to 2½ inches wide and have about 20 petals. Photo courtesy of Julie Overom.5 / 5

LAKE NEBAGAMON, Wis.—For 22 years, Julie Overom has been on a personal mission to develop the perfect rose for more northern climes — a disease-resistant rose as pretty as a hybrid tea and hardy enough to survive Northern winters without being buried.

What began modestly as a backyard hobby cross-breeding roses grew into full-time research that includes a rose farm in Lake Nebagamon and a 30-by-100-foot, commercial-size greenhouse where she spends long days from mid-April to November plus many hours keeping meticulous records.

In her search for the perfect commercially-released Northern rose, Overom has hybridized tens of thousands of roses over the years, producing more than 10,000 new cultivars she has exposed to disease and harsh winters. Along the way, there's been plenty of heartbreak when promising cultivars succumb to disease, harsh winters or fail to thrive.

Now, Overom has done it. One of her rose cultivars will be introduced nationwide next year. The rose — Cherry Frost — has all the qualities Overom sought and more, from resistance to black spot and powdery mildew, Zone 3 hardiness, good form, attractive foliage and abundant clusters of two-inch, 20-petal blooms from July through October. And to her surprise, it did well in varied climates, including California.

To get there, her rose underwent six years of rigorous testing and trials by Star Roses and Plants, a division of Conard-Pyle Co. The Pennsylvania-based company produces landscape plants that it sells to wholesale nurseries, which, in turn, sell to retail garden centers. Of the 1,500 new rose varieties that enter its trials each year, only a few go the distance. The company introduces just five new roses each year, according to Kristen Smith, Star Roses' new plants coordinator.

In 2019, Cherry Frost will be one of them.

"Cherry Frost performed well, exhibited good disease resistance, produced attractive red blossoms throughout the season and overall met all of these checks throughout the process," Smith said.

Some eager gardeners won't have to wait until next year to get a Cherry Frost shrub. It will have a limited release of 1,500 plants this year. Only one garden center in Wisconsin — Northern Family Farms in Merrillan — and one in Minnesota — Bergeson's Nursery in Fertile — will sell Cherry Frost this season.

Joe Bergeson, co-owner of Bergeson's Nursery, has grown Cherry Frost for five years, after getting a plant from Overom to see how well it would do in Northwestern Minnesota. Planted in a field, it has thrived, producing large flower clusters. Now that it's commercially released, he can move it into one of his display gardens for customers to see.

"People are excited about it," Bergeson said of the rose. "It fills a need for a hardy red rose. And it has a massive amount of blossoms."

While there are other hardy roses out there, more are needed, and gardeners are always looking for something new, he said.

A rose hybridizer himself, Bergeson said a commercial release is a big achievement.

"The longer you do this work, the more you realize how hard a path it is," he said. "And Julie has high standards."

He noted that the hybridizing doesn't just require collecting roses to cross-breed and evaluate, but also involves exposing the roses to diseases to test their resistance. For example, black spot, a common and troublesome fungus disease that can severely damage roses, has nine different strains, he said.

"Sometimes a rose can appear beautiful and resistant for five or six years, then it breaks down with ugly black spot," he said.

Overom, 65, has been hybridizing roses on her own, without research funding or grants, making her achievement all the more noteworthy.

"When you're not affiliated with a larger breeder or a big name, nobody knows you," she said. "The chance of making it to introduction are very slim."

At Conard-Pyle's Star Roses and Plants division, the majority of its new rose introductions come from professional breeders around the world, acknowledged Smith. Those from independent breeders often fail to meet the company's criteria for a successful commercial introduction, she added.

"It has been a while since we introduced a rose from a non-professional hybridizer," said Jacques Ferare who oversees the rose program. With most of their trial roses coming from commercial programs, he said the odds of a rose coming from an independent breeder like Overom "are low enough to make (her) story quite remarkable."

A blooming passion

When Overom started gardening in the early 1980s, she went to great lengths to grow tender hybrid tea and floribunda roses. They're beautiful and showy but only hardy to Zone 6, south of Iowa, so they can't survive northern winters without extra protection. Moreover, they need to be sprayed with fungicides and insecticides to ward off disease and pests.

In time, she decided they were too much work. So she switched to perennials and shrub rose varieties more suitable to northern climates, such as Canadian Roses, rugosas, Old Garden roses and wild roses.

Her growing interest in gardening led her to complete the University of Minnesota Extension Service program to become a Master Gardener. She co-founded the Lake Superior Rose Society. She earned a master's degree in plant breeding from the University of Minnesota. And through it all, the mother of three girls worked part time as a medical technician at what is now Essentia Health.

Bolstered by her growing knowledge, in 1996 Overom began crossing hardy shrub roses with tender hybrid teas and floribundas by brushing pollen from one plant onto a flower of another plant that's had its pollen removed. The seeds from the resulting rosehip are used to grow cultivars. The goal is to create a beautiful, healthy, hardy rose on its own root system instead of grafted to wild rose stock which eventually fails.

The combination of science and roses became her passion, one that her husband, Steve, encouraged her to pursue.

In time, Overom was able to use her own cultivators for the crosses, using parent plants with desired characteristics.

Typically, she does about 1,200 crosses a year in her greenhouse. In winter she starts seedlings from the harvested seeds under grow lights in her home in Barnes, 20 miles north of Hayward. In spring, 500 to 550 seedlings are taken to her rose farm, where they are left outside in pots to test for disease-resistance and aesthetic beauty. At the end of summer, she keeps the 50 best plants,with 450 going to compost. At the end of two years, 35 are planted in the ground to determine their winter hardiness. The rest are discarded.

A winning rose

Cherry Frost was the 2006 offspring of a Canadian shrub rose with single pink flowers, good resistance to black spot disease, winter hardiness and the ability to recover from damage that was crossed with one of her hybrid roses that produced numerous dark red cluster blooms, had attractive bright green foliage and a round shrub form.

From early on, it looked like a winner.

"This one stood out from the beginning, with its abundance of blooms," Overom said. "Even as a second-year seeding, I was struck by its color and health. I knew it would be hardy."

The resulting shrub has a round shape with graceful arching stems and clusters of up to 30 floribunda-like blooms at the end of a stem. It typically blooms nearly nonstop from early July well into October while most hardy roses bloom just once. While it can eventually get six feet tall, it doesn't need staking.

By 2009, Overom had several promising cultivars. She sent five in containers to Conard-Pyle Co. The next year, she sent three more. During the following four years, they were tested in Pennsylvania and California. Growing in fields under no-spray conditions, the roses faced leaf spot diseases, mildews and rusts. Overom received annual evaluations on their performance.

"There was ones they liked this or that about," she said. "They want clean foliage with no disease and nonstop blooms."

After three years, all but Cherry Frost had been eliminated. When she heard it was being tested in California, she thought that would be the end of it because the climate is so different than her home climate.

"Instead, it did well — that surprised me," she said.

After four years, Cherry Frost was still in the running. But two more years of trials lay ahead. In California, Cherry Frost had been propagated in large quantities and sent to test gardens in other regions of the country for more evaluation. Sites included test areas in Minneapolis and Milwaukee, according to Overom.

"Cherry Frost was the best performer overall at the end of the two-year trial," Smith said.

In late 2016, Overom got the good news. Cherry Frost was headed for commercial release.

"I'm excited about it," she said last year. But she also fretted. "I'm apprehensive that something could go wrong. When I see my rose in a catalog, that's when I'll know it's real."

The Star Roses and Plants 2019 catalog is due out soon. But four weeks ago, Overom saw her rose, currently in a limited pre-release, in Bergeson's Nursery's catalog.

"For me, it was a thrill to see it in a catalog," she said.

So far, Overom has received no payment for her rose. But she will get a small royalty, split with the company, for each Cherry Frost plant sold.

"I'll never make money at it," she said, noting the considerable amount of money she's spent on plants, soil and other materials over the years. But, she said, it's never been about the money but rather the journey.

"I have loved every minute of this," she said.

Now that she's reached her goal of a commercial introduction, is she's done with hybridizing roses?

"I can't walk away," Overom said. "I love what I do. It satisfies me physically, emotionally and spiritually. It grounds me."

While she looks forward to leaving the greenhouse behind when September arrives each year, in the spring, she's eager to get back.

"I can't wait to get back to the greenhouse and get started," she said. "Walking down the middle of the greenhouse touches me spiritually. "

She doesn't have any cultivars currently going through trials for commercial release, but she says she has three promising candidates.

So soon, she'll be back in her greenhouse, working to cultivate another perfect rose, including the elusive hardy yellow rose, the most difficult one of all.

"Yellow is the holy grail of hardy roses," she said.