Along a path less traveled at the Chicago Botanic Garden, plants are being evaluated on beauty and brawn

The dull visual of a long road is interrupted by a gravel footpath that winds back and forth across the pavement, tiny rocks turning to bricks when the path crosses the asphalt. But the eye is drawn to something else: not the trail, but the greenery growing on its fringes.

Located far away from other attractions at the Chicago Botanic Garden, these plants are being grown in the newest and largest of three gardens. Scientists are evaluating them over the course of several years to determine which ones are best suited to thrive in the Upper Midwest.

“We grow them for three years, four years, five years. Every day during the growing season, we collect data,” said Fred Spicer, executive vice president and director at the Botanic Garden. “How big is it? How wide is it? When did it start flowering? When did it stop? Did it live over winter? All those really good things.”

For his first public commission in the United States, Belgian landscape architect Peter Wirtz was asked to create a garden with plenty of evaluation space as well as an ornamental framework that would encourage visitors to go to an area that used to attract little foot traffic.

At the north entrance to the Mitsuzo and Kyoko Shida Evaluation Garden, two pergolas enveloped in climbing and twining clematis vines welcome visitors. They act like the guardians of a temple, according to Wirtz. And despite the design limitations of an asphalt road, the preexisting nursery and greenhouses and a neighboring lake, Wirtz brought this temple to life with a fusion of movement, color and textures.

Mounds of ornamental grasses in the evaluation garden look like slumbering cats, their blades “wonderfully undulating in the breeze,” Spicer said. “Walk by or drive by and feel the tails brushing your arm.”

European beech...