Growing trees in an urban area is no easy task, but it’s one that City of Knoxville tree experts tackle every year, as more than 500 trees annually are planted throughout the city.

This year, a new technique is being used to strengthen the roots in young trees while minimizing the shock of transplant.

About 100 trees were placed Monday in a Missouri gravel bed at the Knoxville Botanical Garden and Arboretum in East Knoxville. That’s where they will remain for the next six months. The bare-root trees – redbuds, tulip poplars, sweet gums and London planetrees – will be nurtured multiple time a day with a drip irrigation system, and the gravel bed will facilitate stronger root growth. 

By fall, they’ll be ready to be planted. The stronger, better-developed root system eliminates the transplant shock that trees otherwise might experience when moved out of a pot or container.
Not only will the stronger root systems help the trees to survive and eventually thrive, but the gravel bed method is also cost-effective. Kasey Krouse, Knoxville’s urban forester, said the City of Knoxville typically spends about $110 on average per tree with shipping costs. Each gravel bed tree costs between $8 and $15, since the trees are bare-root trees that haven’t been in production in a nursery and do not have bulky root balls to transplant. 

“We’re putting about 100 trees in here, so that’s about 20 percent of the trees we will plant,” Krouse said. “That’s a lot of money that we can be doing other things with to expand our number of trees and the size of the tree canopy within the city.”

With the gravel bed, Krouse said the community could become much more involved – an effort he said is vital to the City’s urban forestry efforts. The Knoxville Botanical Garden will use the bed for educational purposes for anyone visiting the Center for Urban Agriculture, and community members can volunteer to plant the trees, since they are lighter than those with large root balls.
“Anytime we can help save the City money and resources, while we get more creative and get more volunteers involved with the urban forestry program, it’s great,” Krouse said.

For more information about the City’s tree-planting efforts or to assess the City’s 2014 tree canopy report, visit: www.knoxvilletn.gov/trees.

Also, check out this video, in which Krouse demonstrates how trees are being planted in a Missouri gravel bed and how the technique fosters healthier tree root growth.