Garry Oak Trees - Caring for Oak Trees in Oak Harbor


Tree Planting Guidelines


  • Site Preparation
    • Select the right tree for the right place: Choose a species that is suitable for the site's conditions and consider the ultimate size of the tree.
      • Trees need lots of room to grow not only their canopies, but their roots as well.  Root systems of trees, when not well planned out, can lead to damaged underground utilities and plumbing.  
        • Don't forget to look up before planting to avoid any overhead power lines.  
      • For Garry oak trees, keep in mind when the tree reaches a height of over 6', it will fall under the City's tree protection code and be subject to the standards listed
    • Inspect the root ball: Check for circling or girdling roots and straighten or cut them to prevent root problems.
    • Prepare the planting hole: Dig a wide, shallow hole that is 2 to 3 times the width of the root ball but only as deep as the root ball. Do not add gravel or loose soil to the bottom, as this can hinder drainage.
  • Planting the Tree
    • Place the tree: Lift the tree by the root ball, not the trunk, and place it in the hole.
    • Set the correct height: Ensure the top of the root ball is level with or slightly above the surrounding soil. For heavy clay soils, planting the trunk flare 2-3 inches above grade is recommended.
    • Remove all wrapping: Take off the container, burlap, and wire basket. Even if burlap is biodegradable, always completely remove from root ball and planting hole.
    • Straighten the tree: View the tree from multiple angles to ensure it is straight before backfilling.
    • Backfill the hole: Use the native soil that was removed to fill the hole. Gently pack the soil around the root ball to remove air pockets. You can periodically water during backfilling to help settle the soil.  In very dry soils, soaking the planting hole before planting can help with root retention and establishment.
  • After Planting
    • Mulch: Apply a 2- to 3-inch layer of mulch around the base of the tree, keeping it a few inches away from the trunk to prevent moisture buildup against the bark.
      • Prebagged beauty bark is not suggested, rather, use freshly chipped mulch when possible.  Contacting your local tree company is an option as many are happy to dump fresh chip/mulch for free at your property.  
      • Here is a link to a free App: https://getchipdrop.com/     
    • Stake (if necessary): Stake only if the tree is in a windy location or if it is a bare-root tree that cannot stand on its own. Remove stakes after one year.
    • Water thoroughly: Water the tree regularly, especially during the first few years. Keep the soil moist but not waterlogged.
    • Prune early: Perform structural pruning early in the tree's life to develop a strong framework of branches. 
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Tree Planting 2

Maintenance Guidelines

  • For Garry oak tree located within city limits, always apply for a tree pruning permit before work and if possible, consult with an ISA Certified Arborist to identify work to be done.  The permit is free, and the process of application is relatively simple. 
  • Understand the objective: Pruning should have a clear purpose, such as improving structure, mitigating risks, providing clearance, or maintaining health and aesthetics.
  • Limit live foliage removal: Avoid removing more than 25% of a tree's living branches in a single year. Fast-growing trees can handle up to 25%, while slow-growing species should be pruned less, around 10%.
  • Best times of year to prune Garry oak trees are late winter to early spring (Dec-Feb) and mid-summer (July through September).  Avoid times of growth such as mid-late spring (March-June) and times of year when beetle activity is high (Feb-June) 
  • Maintain a strong structure: Prune branches so that each one is no more than half the diameter of the trunk at its point of attachment.
  • Use the correct cuts: Make pruning cuts at the proper location, often just outside the branch collar.
  • Large trees: For high branches or large trees, hire a certified arborist or someone with proper climbing and bucket truck equipment.
  • Removal of dead material is fine at anytime of year and there are no limits to dead wood removal.

Long-Term Tree Care

  • Raking of leaves annually is not necessary as leaves decompose and add to organic material in the soil which helps to create a healthy soil biome.  
  • Mulching when needed to maintain a 1–3-inch layer of mulch around the base of the tree is recommended.  
    • Be careful not to over-mulch as this can lead to root asphyxiation, reduced soil/oxygen exchange, and possible root rot. 
  • With proper mulching and healthy soil, fertilization isn't usually necessary.  When considering fertilizing, always consult with an ISA Certified Arborist or other tree professional with knowledge of soils and tree physiology.     

Proper Pruning Techniques