By Jim McCausland, Sunset senior garden writer

For the past 70 years, an industry association called All-America Rose Selections (AARS) has been evaluating roses bred for sale in America, choosing the best ones each year based on their success in national trials. Along the way they’ve developed considerable expertise about which roses grow best in which climates. This year you can see those regional champs online at the AARS web site.

Looking at the way regions are divided up, I was skeptical: how likely is it that a rose recommended for mild, coastal Camarillo can also be best for blistering Phoenix? To find out, I talked with rosarian Keith Zary. As head rose breeder for Jackson and Perkins, he has an office just a few miles from the California coast near Camarillo, and supervises a 40-acre rose research facility in the hot San Joaquin Valley.

He said that the roses recommended for each region actually do well across all the climates within the region. The Southwest Region recommendations, for example, were chosen both for their ability to resist the mildew common along the coast and the heat that that tends to cook ornamentals inland. Good examples include ‘Gemini’ (above), a pink blend hybrid tea from Jackson and Perkins, and ‘Fourth of July’ (below), a climber from Weeks Roses.

Zary said that doesn’t mean performance will be identical across the zone: a rose that blooms most of the summer in Camarillo will have the summer dormancy common to nearly all roses in the desert. But taking these things into account, the recommended roses will give superior peformance wherever you grow them within the region.

The AARS lists are especially useful because they’re current. The commercial life of an average rose is about 10 years (it disappears from commerce within a decade of its introduction), so roses need to be added and deleted as they come and go from the market. AARS does this, so you have a good chance of finding any rose on the AARS lists.