Chris Boyd has already announced he'll be leaving after the current season to take up a position with English club Northampton.
Jason Holland will be assistant coach with both he and Plumtree signing three-year deals.
Boyd and Plumtree arrived at the Hurricanes in 2015 after working together in Wellington and at the South African side the Sharks.
At that time Boyd said that he had planned that Plumtree would eventually take over from him.
The pair guided the Hurricanes to their maiden Super Rugby title in 2016 after finishing runners-up in 2015.