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No need for a 'cide in these thorns.

New techniques and types get even roses to go green

A bee visits catmint planted among Morris Arboretum's roses. The catmint has oils that act as a pesticide.
A bee visits catmint planted among Morris Arboretum's roses. The catmint has oils that act as a pesticide.Read more

By this time last year, the fabled Rose Garden at Morris Arboretum in Chestnut Hill would've been sprayed with pesticides six or seven times already - 150 gallons a pop, for a total of 2,000 gallons a year.

The amount so far in 2011: zero.

That's because Morris and many other public gardens across the country are tossing toxic chemicals and embracing organic methods in their rose gardens.

"Everyone wants to get away from chemical reliance and move toward enhancing the whole environment of the garden so the roses can be naturally healthy," said Justin Jackson, a landscape architect from Georgia who became Morris' rosarian, or chief rose guy, in August.

Traditional roses - especially the stately hybrid teas, with their classic chubby buds and long stems - have been conspicuous holdouts in the great organic transformation well under way in other sectors of the horticulture world.

Bred and crossbred to be beautiful, but not especially tough, these roses have historically reigned as the undisputed fusspots of public gardens and many a home garden. Though glamorous, they are extremely high maintenance.

If not sprayed regularly during the growing season, and sometimes even if they are, they're susceptible to black spot, powdery mildew, and other diseases, as well as thrips, aphids, spider mites, and the dreaded Japanese beetle - not a mix any arboretum wants on display, especially in rose gardens, which are perennial favorites with visitors.

This year at Morris, using a grant from the University of Pennsylvania's Green Fund, the uptight fusspots are turning hip. Jackson is using a laid-back approach to maintenance that emphasizes plant variety, soil health, and the integration of roses into the garden's ecosystem.

Instead of donning a hazmat suit and spraying fungicides, insecticides, and herbicides, or downloading generous amounts of synthetic fertilizer to boost growth, Jackson is outfitted in work clothes and a straw hat, spraying a far less hazardous liquid - compost tea, a natural fertilizer made by soaking or steeping decomposed organic matter, such as grass clippings, leaves, weeds, sawdust, and wood chips, in a huge vat of water.

The rich "tea" will provide nutrients and beneficial fungi to suppress disease among the arboretum's 1,000-plus roses, most in the one-acre Rose Garden, which dates to 1888. Compost tea also creates stronger, deeper roots, which hold water better; Jackson estimates this will lower watering needs by one-third.

Going forward, he'll be looking for rose varieties with high disease resistance, and he'll install more so-called companion plants, whose leaves, flowers, or roots repel undesirable insects or attract desirable ones.

For example, yarrow attracts ladybugs, which like to eat aphids. Nepeta, or catmint, attracts butterflies and contains oils that work as pesticides.

Companion plants also are long-blooming and colorful, capable of "carrying the garden through the season when a lot of the roses have stopped," Jackson said.

That raises another issue: Compared with other flowering plants, roses are held to a ridiculously high standard by the public, whose views are shaped by mass marketing, especially around Valentine's Day. That perfection can be achieved only through chemicals.

"The standard set was way too high for the average home gardener. It's a trap," said Paul F. Zimmerman of Campobello, S.C., a former rose nursery owner who runs Paul Zimmerman Roses, "a company dedicated to teaching that roses are plants, too."

"It's like, 'Here's a lovely rose for $20, but you need $250 in chemicals to take care of it,' which if you're a stockholder in Dow Chemical is a pretty groovy thing," said Zimmerman.

But if you're typical of the times, you're way too busy already, and probably intimidated and turned off by such a protocol. That is why Zimmerman prefers to define roses as "nothing more than a shrub with flowers on it."

"Nature is never perfect, and a rose garden isn't meant to be, either," he said.

Which helps explain the enormous popularity of Knock Outs, the relatively undemanding, highly disease-resistant, and everblooming shrub that jolted the struggling rose world when the Conard-Pyle Co. in Penn Township, Chester County, introduced it in 2000.

Knock Outs - there are seven now, more in the works - would never cut it at a rose competition, but consumers and landscapers love them. The original Knock Out is the No. 1-selling rose in the United States, said Steven B. Hutton, Conard-Pyle president and third-generation nurseryman, who estimates sales of all roses in the Knock Out series at "tens and tens of millions."

Snubs from sophisticated rosarians sting a bit, he acknowledged, but not much. It's obvious why: Of the 35 million rose plants bought annually in the United States, fewer than 10 million are the traditional types.

The rest are easygoing garden roses - like Knock Out.

"You can breed a rose to be a racehorse or a plow horse," Hutton said, and judging from Knock Out's success, it's clear he prefers field to track.

It's also clear that this is where the survival-minded rose industry is headed.

In the not-too-distant future, Hutton predicted, traditional hybrid tea roses will be everything they are now, without the bad stuff. In other words, they'll be Valentine-worthy, but instead of being short-blooming, short-lived, and vulnerable to pests and disease, they'll bloom and live for a long time, be easy to grow, fend off most of the garden's bad actors through organic methods, and - hear, hear - have great fragrance, a quality many roses lost in the breeding process.

No matter what, even places farther down the organic road than the Penn-affiliated Morris still have a few aphids and a bit of black spot. But Jackson - who previously worked at the Atlanta Botanical Garden, where the rose garden has been all-organic since 2003 - is OK with that.

"It's about managing expectations," he said. "You don't have to expect perfection out of roses. They're going to give you a good show regardless."

So while the Rose Garden will soon have more beneficial insects and pollinators, it most likely will still host pests - like the dive-bombing gnats that Susan Margasak of Flourtown and Joan Tallman of Hatboro encountered.

As the pair of visitors swatted their way past a swath of creamy apricot and pale yellow roses, they chatted about how old-fashioned, nonchemical gardening is back in vogue. (Tallman confessed to using Roundup in a pinch.)

Margasak suddenly had an idea. "To keep these bugs away, we could put dryer sheets around our necks," she suggested.

Tallman frowned. "A dryer sheet! You don't know what's in there," she said. "You know - chemicals."

"Never mind," Margasak said. "We'll get cancer."