Landscape Plants of the Upper Midwest

Green Ash

{Picture of Green Ash}

Plant Information

  • Plant Type: Tree: Large
  • Scientific Name: Fraxinus pennsylvanica Play audio of plant name
  • Family: Ash
  • Related Cultivars:

    Fraxinus pennsylvanica 'Johnson'
    Fraxinus pennsylvanica 'Marshall's Seedless'
    Fraxinus pennsylvanica 'Patmore'
    Fraxinus pennsylvanica 'Summit'

  • Zone: 3
  • Plant Size: 50-60'
  • Habit: Oval
  • Culture:

    Extremely adaptable. Tolerates wet conditions. Full sun.

  • Notes:

    It is no longer recommended to plant this species in the upper Midwest due to its susceptibility to the emerald ash borer (see information below).

    Before the introduction of the emerald ash borer, this species' adaptability and growth rate resulted in it becoming over-planted, especially considering its frequent disease and insect problems and lack of ornamental interest. Young plants were popular because of a strait trunk, rapid growth rate and symmetrical habit. Dioecious.

  • Emerald Ash borer:

    All of the ash species natives to North America are susceptible to the Emerald Ash Borer, an insect introduced from China. This insect originally became established in southern Michigan, and has now spread thoughout most of the eastern U.S. and southeastern Canada. This exotic insect has devastated ash populations in these areas. If you live in the eastern or central United States, ash species should not be planted. The most up-to-date information on this insect can be found at:

  • Pruning:Pruning animation

    Structural pruning targets branch defects with the goal of producing strong-branched, long-lived trees with a low risk of storm damage.  The importance of addressing branch defects when trees are young cannot be over-emphasized. The suppression or removal of small branches is far easier and better for long-term tree health than when branches become large.  Beginning when a tree is planted, it should be evaluated each year and branches with structural defects should be suppressed, or if small, removed.  This will promote a resilient tree structure that is also more ascetically pleasing.    

    These site explain the fundamentals of structural tree pruning:

    Urban Tree Foundation – Structural Pruning

    University of Florida – Structural Pruning

    If a branch needs to be removed for clearance, is damaged, or possesses a critical defect, a 3-point cut is used (see animation). First an undercut is made to prevent bark from tearing down the trunk if it remains attached to the falling limb. The branch is then "stub cut" which removes most of the branch to facilitate a clean final cut. The final cut is made just outside the branch collar, which is the swollen area between the branch and the trunk. Cuts made here will heal most readily and prevent rot from invading the main trunk of the tree, a common occurrence when branches are cut flush with the trunk.

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Landscape Plants of the Upper Midwest

Bill Hoch, Associate Professor
Montana State University

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