Historic Garden Nurtures Native Southeastern Plants

When horticulturist Brian Campbell started working at the Knoxville Botanical Garden, he conducted a plant density study of acreage that had been home to the historic Howell Nurseries' greenhouses.  He determined that less than half of the plant life was native.  This was compared to an average of about 80% native plant life in most of the United States. While East Knoxville takes pride in preserving the nurseries' heritage, the public space now aims to restore at least some of the acreage to native Tennessee botanicals.

Campbell pointed to the dense thicket of bamboo that the grounds crew can only hope to contain, but won't try to remove. "It's so aggressive," Campbell said of the bamboo, "it's almost impossible to get rid of."

Knoxville Botanical Garden's Director of Horticulture let me walk with him through a meadow that overlooks a distant view of the Great Smoky Mountains.  Campbell said that instead of removing all of the exotic plants, the process has been to introduce more native plants and give them a chance to thrive. One indicator that it's working is the abundance of pollinators buzzing through the field.  Why nurture so many modest, native plants? "It's pretty much all about diversity," he answered.

The meadow attracts bees and butterflies with black- eyed Susans, pawpaw trees for hosting zebra swallowtails, and 200 butterfly weeds (milkweed) that can be homes to monarch young.   A smaller butterfly garden is under construction at the meadow's edge to help teach visiting groups of students and families.  Campbell plans to eventually bring back native grasses to the meadow, such as switchgrass and big and little bluestem.

An inviting outdoor classroom is shaded by a grove of hardwood trees near a varied arboreal display. Here, grounds crews have removed several nonnative trees and added natives like black cherry and paw paw.  Redbud and dogwood are also good host trees for attracting wildlife. Tiny dried black cherry fruits have dropped on the ground.  Campbell tells me that butterflies rely on that rotting fruit to get tiny sips of life-giving water.  Considering the value of a tree to help wildlife adds another dimension beyond aesthetics. Without the host paw paw tree, Tennessee wouldn't have its state butterfly, the zebra swallowtail.

Campbell says that when he teaches classes to master gardener students and others he makes sure not to preach about the dangers of exotic, invasive plants.  He acknowledges that some plants have naturalized without causing too much danger to other plants.  Yet, he mentions that varieties listed as invasive, that can choke out native plants while depriving native wildlife of the habitat it needs.  He suggests that gardeners seek out local plant nurseries and educate themselves about the benefits of native plants.  "If you want to be a good steward of the land, know what you're planting," Campbell stressed,  "we're all in this together."