Trees 2.0

A new way to fight disease and create a greener county

For county arborists, the emerald ash borer is public enemy #1

Of the approximately six million trees that the county maintains, nearly one million are ash trees. And the majority of them are within 15 miles of trees that are already infected.

One of the county’s main objectives is to replace dead ash trees. This will increase the county’s tree canopy and provide cost-effective and diverse trees to fight against an ongoing emerald ash borer pest problem.

In the spring of 2015, the county created a gravel-bed nursery at the Adult Corrections Facility in Plymouth to aid in this effort. The gravel-bed nursery is an irrigated planting bed that stores bare root trees while encouraging rapid root growth. The trees are planted in the gravel bed during the spring, watered consistently all spring and summer, and then transplanted in the fall. The nursery has 500 trees, representing 14 different species.

Gravel bedding to a better county

Increasing the county’s tree canopy is beneficial to Hennepin County residents in a number of ways. It:

  • Improves air and water quality
  • Reduces storm water run-off
  • Reduces heat-island effects
  • Preserves habitats

You can recognize trees that are infected by emerald ash borer by looking for:

  • Heavy woodpecker activity – they feed on the beetles
  • Dead branches in the top canopy
  • Leaves around the tree base
  • Vertical cracks in the bark
  • S-shaped tunnels under the bark

The future of Hennepin County gravel-bed planting

In 2015, Hennepin County was able to plant nearly 300 trees in 12 different sites. The project helped to replace trees designated for removal, increased canopy area, replaced failed plantings, and restored native woodland.

In 2016, the county plans to plant about 500 more trees. The nursery provides an opportunity for Sentencing to Service crews and community volunteers to help create a greener and more habitable Hennepin County.

Learn more about the county’s commitment to the environment at

www.hennepin.us/residents#environment