Roses have a reputation for being difficult to grow and disease prone. But who’s really to blame?
We are, said Peter E. Kukielski, a rosarian and the author of “Rosa: The Story of the Rose,” a new book about the flower’s place in human cultural history. After the genus Rosa had survived some 35 million years on the planet, it took us less than a century to render it less resilient than it had to have been to stick around that long.
“It has to be one tough plant to go through all the climate changes and everything else it’s through before we started hybridizing roses,” Kukielski said, referring to the human interventions to change the flower’s shape gone into what became the hybrid tea, achieved at the expense of disease resistance.
So “give them some credit,” he said. And give them some proper companions, too: flowering perennials, annuals and bulbs that foster a healthier rose garden, without chemical intervention. Like the one he designed three years ago for the Royal Botanical Gardens in Ontario — a chemical-free province — that he proudly describes as “3,000 roses and 18,000 perennials chosen as insect-attracting companions.”
He added: “I don’t mind bad insects. As long as we have the good insects, we will have balance.”
It’s no surprise that Kukielski doesn’t recommend a diet of synthetic fertilizer, or propping roses up with pesticides and fungicides if spider mites or black spot threaten. As a curator at the New York Botanical Garden, he won attention for his work from 2008 to 2014 on the Peggy Rockefeller Rose Garden — an approach that involved planting and trialing roses for disease resistance, using fewer chemicals.
That experience served as research for his first book, “Roses Without Chemicals: 150 Disease-Free Varieties That Will Change the Way You Grow Roses.”
“When I first did the garden revamp,” he said, “choices of disease-resistant roses were kind of limited.”
But now there are many more roses bred with that intent, he said: “The rose world woke up to the idea that gardeners don’t want to rely on chemicals to grow their favorite flowers.
Matching roses to regions
That pink rose on the latest catalog cover looks delicious, but wait: How would it fare where you garden, compared to similar-looking varieties?
“A rose is a rose is a rose… not,” Kukielski said. “Choosing the right one for your climate region can make for instant success. But the wrong rose will constantly be diminished, and the home gardener may give up.”
Fortunately, he said, more companies are now educating customers about which regions a variety is best suited to: “It’s certainly an advance from where we were even five years ago.”
Breeders (on their wholesale websites) and retailers (on their consumer-focused ones) often make it possible to filter varieties by regional adaptability and disease resistance. So rose-shopping gardeners take note — and do your homework.
And the winner is …
There is no better proof of a plant’s durability than having data on what happens when it’s put to the test of multiyear garden trials in diverse regions. One program currently underway is the American Rose Trials for Sustainability, which Kukielski co-founded.
The trials are taking place at Longwood Gardens, the Scott Arboretum of Swarthmore College, Tucson Botanicals Gardens and university cooperative extension sites around the country, where roses are subjected to the challenge of no-spray environments, and offered no help from pesticides and fungicides.
For local information, try asking at garden centers with landscaping businesses, where employees may be able to recommend varieties that perform well for clients near you.
Or talk to the local rose society, Kukielski suggested, and neighbors who garden: “If the person down the street is growing Queen Elizabeth and it looks great, take that as a cue.”
Feed the soil, not the plants
Think healthy soil, not bagged fertilizer, Kukielski advised. “When I stopped feeding my roses and started feeding the soil,” he said, “the rose garden became a lot easier.”
He was inspired by the Earth-Kind methods promoted by Texas A&M AgriLife Extension. The inspiration for the soil-management practice: “Think forest floor, where nobody fertilizes but leaves fall, that then break down and feed plants.”
To mimic that process, he puts down three inches of mulch, maybe an inch of which has decomposed into humus by season’s end, benefiting soil health and fertility. “Just top up the mulch again next spring — but don’t disturb the soil,” he said. “Once we started doing that at NYBG you could just tell that the plants were happier. There was a big difference by Year 3.”
The next challenge: Rose rosette disease
Today, rose researchers and breeders face a formidable opponent. Rose rosette disease, a naturally occurring virus, is spread by a tiny, windblown mite that has used the invasive multiflora rose as a host to expand into an increasing territory.
Early symptoms of infection include abnormal growth: excessive thorns, red pigmentation and general disfigurement — even what is known as witch’s broom, growth that resembles birds’ nests.
Industry and university experts have created a website about the disease and ongoing efforts to combat it. But at the moment, only vigilance — including eradicating nearby multiflora roses — and drastic measures are prescribed.
“If the gardener does discover it in the garden, the plant should be removed and destroyed, roots and all,” Kukielski said.
Growing roses in San Diego
The San Diego Rose Society has lots of information about how to grow roses in the region’s Mediterranean climate including the best places to plant them, how to prepare the soil, when to prune, how to prevent pests and disease and which varieties grow well in San Diego. Diego.
Some of their picks by color categories include:
Net: “Mister Lincoln,” a hybrid tea rose that was named an All-America Rose Selections winner in 1965
Pink: “Flower Girl,” a saucer-shaped medium rose that does well in full sun
Apricot: “Marilyn Monroe,” a hybrid tea rose with voluptuous blooms. Heat tolerant.
White: “Iceberg,” one of the world’s most popular roses, known for producing abundant blooms all year long
Yellow: “Gold Medal,” a sturdy rose with large blooms that are often tinged with copper and produces a pleasing fruity fragrance
For more information, visit sandiegorosesociety.com
Margaret Roach writes for The New York Times.