Northwestern University researchers find cultivated garden flowers can still be pollinator-friendly

A new Northwestern University study is challenging what some gardeners might think they know about pollinator-friendly landscaping.

The study issued last week by plant biologists from Northwestern and the Chicago Botanic Garden said helping pollinators such as bees and butterflies does not require going totally wild with native plants only. The researchers found some cultivated flowers can also provide strong support, especially in home gardens.

Pollinator gardens have been around for many years, but took off in the mid-2000s as gardeners were alarmed by the decline of honeybees. Pollinator gardens have usually prioritized native plants that grow and bloom in the wild without human intervention, and have avoided cultivated varieties.

Wildtype plants retain traits that they evolved through thousands of years of evolution to draw pollinators, while cultivars are bred for aesthetic appeal to people rather than attraction for bees and butterflies. But researchers found this does not mean cultivars are no good for pollinators.

The study, published in the journal Ecosphere, tested several plants for how well they supported pollinators. Researchers found the cultivated black-eyed Susan (Rudbeckia fulgida "Goldsturm") and the foxglove beardtongue (Penstemon digitalis "Husker Red") both attracted pollinators at similar rates to their wild counterparts.

Other cultivated plants such as R. fulgida "American Gold Rush" and P. digitalis "Blackbeard," were not as useful in attracting pollinators, the study found.

The point is that attracting pollinators and being eco-friendly does not have to come at the expense of beauty and aesthetics. Rather, a thoughtfully planned mix of cultivated flowers and wildflowers might be the best option, the study found.

"Our findings emphasize that ecological value and aesthetics don't have to be at odds with each other," the Chicago Botanic Garden's Nicholas Dorian, the study's lead author, said in a news release. "There are many people who might be interested in getting involved in the pollinator gardening movement but feel intimidated. Turning a garden or front yard into a wild space can feel daunting. A key takeaway from our study is that cultivated plants with aesthetic appeal can still bring pollinators into your yard and may be a really nice gateway for people who are on the fence or don't have time or resources to seek out wildtype plants."

The study involved a controlled experiment in which four native plant species were planted around 13 cultivated plant species in the same plot, and observed for two years. Researchers counted the number of insects — including bumblebees, honeybees, butterflies, moths, and beetles — that visited the reproductive features of the flowers.

Researchers also had volunteers plant the same flowers in backyards, schoolyards, and public spaces and track pollinator insects.