Should We Be Planting Only Native Plants

Source: Clackamas County Soil and Conservation District.

Ferris Jabr, a science writer and Portland gardener, has an excellent story in today's New York Times that explores the question of whether gardeners should limit themselves to native plants. The article's subtitle captures the conclusion: "The native plant movement gets a lot right, but there’s so much more to consider."

But what does Jabr mean by "native plant movement?" In this case, he means Doug Tallamy. Tallamy is a professor of Entomology and Ecology at the University of Delaware and author of Bringing Nature Home, Nature's Best Hope, and the Nature of Oaks among others. For Jabr, Tallamy "is the nation’s foremost expert advocate for gardening with native plants" and that "[m]any of the native plant movement’s followers regard Tallamy with the kind of deep reverence typically reserved for spiritual leaders." Tallamy, then, becomes a useful stand-in for the native plant movement as a whole. 

Jabr interviews Tallamy at his 10-acrec farm in Pennsylvania, which he and his entomologist wife re-wilded over a period of decades. He writes that Tallamy "is convinced that the coevolved relationships between native plants and insects sustain all terrestrial food webs and that typical American gardens, landscaped with lawns and showy exotics, are essentially ecological wastelands. He argues that foreign and invasive plant species — most of which have been introduced through the ornamental plant trade — are some of the primary causes of the so-called insect apocalypse and the current staggering rates of biodiversity loss more broadly." 

Or, as another writer complains, Tallamy“saddles everyman gardeners (whether they wished to grow Hemerocallis [daylilies] or fill a raised bed with herbs) with the burdens of past and present ecological damage to our planet, the saving of species from extinction, and the reversal of climate change.” 

Tallamy's attitude is nicely captured in the title of author Eileen Starks' book Real Gardeners Grow Natives  (a useful book on Pacific Northwest native plants). In her promotional material, Stark writes "Native plants—especially when grown in natural plant communities—are the foundation of the food web. They support drastically more insect biomass than nonnatives and provide other essentials for the wild creatures who bullt an evolutionary partnership with them eons ago. When we garden with natives, we’re doing crucial conservation work, and doing ourselves a favas as well, because native plants are low-maintenance, often drought tolerant, and easily compete with the beauty of exotic plants."

And here's the crux of the matter: should we be planting only native plants in our home gardens and urban landscapes? Will a strict palette of native plants in urban environments help avert our biodiversity crisis? I think the answer is clearly no. As Jabr points out, "[t]he most formidable challenges to Tallamy’s grand vision are not the nuances of nativeness but the realities of scale." He continues: "More than half the land in the contiguous United States is devoted not to gardens, parks or golf courses but to farms and ranches. Another 30 percent is managed forest, much of which is logged. Less than 6 percent is occupied by cities, major suburbs and their constituent green spaces."

Urban land is a novel ecosystem that has its own its own dynamics and a unique set of stressors and constraints (and perhaps even a few opportunities). To meet the context of the urban environment, we can't limit ourselves to history's most recent offering of native plants.