The Smart Way to Grow Roses

Roses have a reputation for being difficult to grow and prone to disease. But who is really to blame?

We are, said Peter E. Kukielski, a rosary and the author of “Rosa: The Story of the Rose,” a new book on the flower’s place in human cultural history. After the genus Rosa survived some 35 million years on the planet, it took us less than a century to make it less resistant than it should have been to stay that long.

“It must be a tough plant to get through all of the climate change and whatever it went through before it started hybridizing roses,” Kukielski said, referring to human interventions to change the shape of the flower to this. which has become hybrid tea, at the expense of disease resistance.

So “give them credit,” he said. And also give them good companions: flowering perennials, annuals and bulbs that promote a healthier rose garden, without chemical intervention. Like the one he designed three years ago for the Royal Botanic Gardens of Ontario – a chemical-free province – which he proudly describes as “3,000 roses and 18,000 perennials chosen as insect-attracting companions.” .

He added, “I don’t care about bad bugs. As long as we have the right insects, we will have a balance.

It’s no surprise that Mr. Kukielski doesn’t recommend a synthetic fertilizer regime or supporting roses with pesticides and fungicides if spider mites or black spots are threatening. As a curator at the New York Botanical Garden, he drew attention for his 2008-2014 work on the Peggy Rockefeller Rose Garden – an approach that involved planting and testing roses for disease resistance, using fewer chemicals. This served as research for her first book, “Roses Without Chemicals: 150 Disease-Free Varieties That Will Change The Way You Grow Roses.”

“When I did the garden renovation for the first time,” he said, “the choices of disease-resistant roses were pretty limited.”

But now there are many more roses grown with this intention, he said: “The rose world has woken up to the idea that gardeners don’t want to rely on chemicals to grow their plants. favorite flowers. “

That pink rose on the last cover of the catalog looks delicious, but wait: how would it be where you garden, compared to similar varieties?

“A rose is a rose is a rose… no,” Mr. Kukielski said. “Choosing the right one for your climatic region can be an immediate success. But the bad rose will be constantly diminished, and the home gardener may give up.

Fortunately, he said, more and more companies are now educating customers on which regions a variety is best suited to: “It’s definitely an improvement over where we were five years ago. . “

Breeders (on their wholesale websites) and retailers (on their consumer-oriented sites) often allow varieties to be filtered based on their regional adaptability and disease resistance. So rose gardeners take note – and do your homework.

Some breeds have focused on cold hardiness, producing varieties like the Buck roses by Griffith J. Buck from Iowa State University or the Easy Elegance roses produced by Ping Lim. Other varieties take up the opposite challenge: the Sunbelt collection from Kordes Roses is selected for its high performance in warmer areas.

Some series of trademarks are marketed for their resistance, including Carefree, Knock Out, Drift, and Oso Easy, although there may be genetic tradeoffs. As Mr. Kukielski pointed out, “When a series has been pushed to fill an entire color wheel with varieties, some colors – especially yellow – may be less resistant.”

The scent can also be diminished.

“If you want a fragrant garden, depending on where you live there may be disease issues,” Kukielski said. “Fragrance-focused breeding efforts may not have the resistance, especially in hot, humid climates, against fungal diseases.”

But putting the scent back is on some breeders’ to-do lists, he said. One example is the Parfuma collection from Kordes, a company long focused on disease resistance.

There is no better proof of a plant’s durability than having data on what happens when it is put to the test of multi-year garden trials in various regions. One of the programs currently underway is the American Rose Trials for Sustainability, which Mr. Kukielski co-founded, taking place at Longwood Gardens, the Scott Arboretum at Swarthmore College, Tucson Botanicals Gardens and extension sites in University cooperatives across the country, where roses face the challenge of spray-free environments, offered no help from pesticides and fungicides.

Another is the American Garden Rose Selections Trials, with testing sites at the Queens Botanical Garden, Chicago Botanic Garden, and other locations in various areas.

Both programs publish results and recommended varieties each year.

For local information, try asking garden centers with landscaping companies, where employees may be able to recommend varieties that work well for customers near you.

Or talk to the local rose company, Mr Kukielski suggested, and neighbors who are gardening: “If the person down the street grows Queen Elizabeth and it looks good, take that as a clue.”

Mr. Kukielski’s definition of a modern rose garden at any scale: “Not a monoculture, but a mixed border.”

In his rose beds, he lays a long season of companion plants, using a heavy hand, emphasizing the types of flowers preferred by beneficial insects (pollinators, predators and parasites). Grouping several plants of the same variety together makes for a more inviting appearance than scattering single plants.

Of course, there are the classic rose companions: Lady’s mantle chartreuse moss (Alchemilla mollis) or catmint (Nepeta), with clematis climbing the shrubs. A range of Alliums – from the tiny yellow-flowered A. moly to the towering purple Globemaster – and, later, the auto-seeded annual Verbena bonariensis (a butterfly favorite) are making big statements.

But Mr. Kukielski also likes the umbel-shaped flowers of members of the carrot family, which attract many beneficial insects – including, he hopes, spotted flies, especially a species imported in the 1920s. as a biological control of Japan, where it is a natural enemy of the Japanese beetle which is a plague on roses.

He also likes the yellow dill umbels, its fern texture and its inclination to sow. And it allows the coriander to bloom and self-seed along the edges of the garden.

Beyond dill and cilantro, the favorite herbs are tansy, feverfew, lavender, and thyme.

Composite or daisy-shaped flowers have great insect appeal and Mr. Kukielski uses many of them, including asters, gloriosa daisy (Rudbeckia fulgida), coneflower (Echinacea), Cosmos, sneezes (Helenium) and yarrow (Achillea millefolium).

Native plants are, of course, special magnets for insects: besides aster, Rudbeckia, Helenium and coneflowers, M. Kukielski prefers Zizia aptera, wild bergamot (Monarda fistulosa), butterfly weeds (Asclepias tuberosa) and cultivars of Penstemon, Phlox paniculata and goldenrod (Solidago), as well as perennial grasses such as sporobolus heterolepis (Sporobolus heterolepis) and switchgrass (Panicum virgatum).

Think of healthy soil, not bagged fertilizer, Kukielski advised. “When I stopped feeding my roses and started feeding the soil,” he says, “the rose garden just got a lot easier.”

He was inspired by the Earth-Kind methods promoted by Texas A&M AgriLife Extension. The inspiration for the practice of soil management, as he translates it: “Think of the forest soil, where no one fertilizes but drops it, which then decomposes and nourishes the plants.

To mimic this process, he lays down three inches of mulch, perhaps an inch of which has decomposed into humus at the end of the season, which benefits the health and fertility of the soil.

“Just add more mulch next spring – but don’t disturb the soil,” he says. “Once we started doing this at NYBG, you could just tell the plants were happier. There was a big difference in the third year. “

In his vegetable garden in Maine, he also allows fallen tree leaves to stay put and degrade. He hasn’t fertilized for three or four years, he said, beyond occasional soaking of the soil with diluted fish emulsion.

By using disease-resistant roses suitable for the region, Mr. Kukielski was also able to break rose spacing rules established to minimize black spots.

“When I started the Peggy Rockefeller Garden, I got comments about it,” he recalls. “The plants should be six feet apart,” the people said. But the new hybrids are so tough I can relate them. And as they grow together, the colors really come through – you paint with the colors.

Today, rose researchers and breeders face a formidable adversary. Rose rosette disease, a natural virus, is spread by a tiny windblown mite that has used the invasive multi-flowered rose as a host to spread over growing territory.

Early symptoms of the infection include abnormal growth: excessive thorns, red pigmentation, and general disfigurement – even something called witches’ broom, a growth that resembles bird nests.

Experts from industry and academia have created a website about the disease and the ongoing efforts to combat it. But for now, only vigilance – including the eradication of neighboring multiflora roses – and drastic measures are prescribed.

“If the gardener finds it in the garden, the plant has to be removed and destroyed, the roots and everything,” Mr. Kukielski said.

But a new rose can be planted right away, because the virus cannot live in the soil. Or you can just let all of those companion plants take over.

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