Learning how to prune arborvitae is a key skill for keeping these popular evergreens healthy and looking their best. Pruning arborvitae is best done with restraint, focusing on light shaping and the removal of damaged or dead growth. This guide will walk you through the entire process, from choosing the right tools to making the correct cuts.
Arborvitae are resilient trees, but improper pruning can cause lasting damage. With the right approach, you can encourage dense foliage, maintain a desired size, and solve common problems. We will cover everything you need to know to prune with confidence.
How To Prune Arborvitae
This section outlines the core principles and the step-by-step method for pruning your arborvitae. Following a systematic approach ensures you achieve your goals without harming the tree.
Essential Tools For The Job
Having the proper tools makes pruning safer and more effective. Clean, sharp tools make precise cuts that heal quickly.
- Hand Pruners (Bypass Style): Ideal for cutting small branches and twigs up to about 1/2 inch in diameter. Bypass pruners make a clean cut like scissors.
- Loppers: Use these for branches between 1/2 inch and 1 1/2 inches thick. Their long handles provide leverage for cutting tougher wood.
- Hedge Shears (for shaping only): Only use these for light, formal shaping of the outermost green growth. Do not use them for cutting large or woody branches.
- Pruning Saw: Necessary for removing any branches larger than 1 1/2 inches. A sharp saw is crucial for a clean cut on thicker wood.
- Safety Gear: Always wear protective gloves and safety glasses to shield your hands and eyes from debris.
The Best Time To Prune Arborvitae
Timing your pruning correctly is vital for the tree’s recovery and growth. The ideal window depends on your primary goal.
- Late Spring to Early Summer (Ideal): The absolute best time is after the new, light green “candles” of growth have fully expanded but before summer’s heat arrives. This allows the tree to recover quickly and put energy into remaining growth.
- Early Spring (for Major Corrections): You can do more significant structural pruning just before new growth begins. The tree’s energy is about to surge, aiding in healing.
- When to Avoid Pruning: Do not prune in late summer or fall. New growth stimulated at this time will not harden off before winter and is likely to be killed by frost, leaving the tree vulnerable.
Step By Step Pruning Instructions
Follow these steps in order for a successful pruning session. Always start with the most important cuts and work toward shaping.
Step 1: Sanitize Your Tools
Before you make a single cut, wipe the blades of your tools with a disinfectant like rubbing alcohol or a bleach solution. This prevents spreading disease from plant to plant.
Step 2: Remove Dead, Damaged, and Diseased Wood
Start by identifying any problematic branches. Look for brown, brittle, broken, or discolored growth. Cut these branches back to the main trunk or a healthy lateral branch. Removing this wood first improves air circulation and plant health.
Step 3: Thin for Light and Air
Thinning involves selectively removing entire branches back to the trunk to open up the tree’s interior. This is not about shearing the outside. Find areas where branches are overly crowded and remove a few to allow light and air to penetrate. This reduces the risk of fungal diseases that thrive in damp, dark conditions.
Step 4: Address Crossing or Rubbing Branches
Look for branches that are crossing over each other and rubbing. The constant friction creates wounds that can become entry points for pests and disease. Choose one of the rubbing branches to remove, typically the weaker or less desirably placed one.
Step 5: Light Shaping and Shearing (If Desired)
If you want a formal, shaped look, this is the final step. Using hedge shears, lightly trim the current season’s soft, green growth to define the shape. Never cut back into the old, brown wood, as arborvitae often will not regenerate new growth from these areas. Always shape the tree so the base is slightly wider than the top; this allows sunlight to reach the lower branches.
Common Pruning Mistakes To Avoid
Being aware of these frequent errors will help you protect your arborvitae from unnecessary stress and damage.
- Topping the Tree: Cutting off the central leader or flat-topping the tree destroys its natural form and leads to weak, unattractive regrowth.
- Cutting Into Old Wood: Shearing or cutting back into branches where there is no green foliage visible usually results in permanent bare spots.
- Over-Pruning: Removing more than 25-30% of the tree’s foliage in a single season can severely shock it, stunting growth or even causing death.
- Using Dull or Dirty Tools: Dull tools create ragged tears that heal slowly. Dirty tools spread infection.
- Creating a “V” Shape: Shearing the tree so it’s narrower at the bottom than the top shades the lower branches, causing them to thin out and die back over time.
Pruning Different Types Of Arborvitae
Not all arborvitae varieties are pruned the exact same way. Your approach should consider the tree’s natural growth habit and your landscape goal.
Pruning Pyramidal Or Columnar Varieties
Varieties like ‘Emerald Green’ (Smaragd) or ‘Degroot’s Spire’ have a natural, narrow form. The goal is to enhance this shape, not fight it.
- Focus on minimal pruning to maintain a tidy appearance.
- Lightly shear the new growth in early summer to encourage density.
- Always maintain the natural taper, keeping the base the widest point.
Pruning Globe Or Rounded Varieties
Varieties like ‘Danica’ or ‘Golden Globe’ are bred to be compact and round. They require very little pruning.
- Limit pruning to the removal of any stray or damaged branches that spoil the rounded shape.
- If needed, lightly shear the surface to tighten the globe form, but avoid cutting too deeply.
Pruning Overgrown Or Neglected Arborvitae
Reviving an overgrown arborvitae requires patience. You often cannot fix it in a single season.
- In early spring, remove all dead and diseased wood completely.
- Thin out the interior by removing select branches back to the trunk to improve light penetration.
- Over 2-3 seasons, you can gradually reduce the height and width by cutting back to a lateral branch that is pointing in a desierable direction. Do not remove all the green growth from a branch.
Aftercare And Maintenance
What you do after pruning supports the tree’s recovery and long-term health. Proper aftercare is simple but important.
Watering And Fertilizing After Pruning
A light pruning typically doesn’t require special care, but significant pruning benefits from support.
- Water the tree deeply after a major pruning session to alleviate stress and support root health.
- You can apply a balanced, slow-release fertilizer in the spring following pruning to encourage healthy new growth, but avoid over-fertilizing.
Monitoring For Pests And Disease
Fresh cuts can sometimes attract pests. Keep an eye on your tree in the weeks after pruning.
- Look for signs of bagworms, spider mites, or fungal issues like tip blight.
- Early detection makes any treatment much more easier and effective.
Frequently Asked Questions
Can You Prune Arborvitae In The Fall?
It is not recommended. Pruning in fall stimulates tender new growth that will not survive winter frosts, potentially damaging the tree. The best time remains late spring to early summer.
How Much Can You Cut Off An Arborvitae?
As a general rule, never remove more than one-third of the tree’s total green foliage in a single year. For severe overgrowth, spread the pruning over two or three seasons to avoid shocking the plant.
Will Arborvitae Grow Back After Pruning?
Yes, but with a critical caveat. Arborvitae will readily produce new growth from areas that still have green needles. If you cut back into bare, brown wood where no green exists, it is unlikely to sprout new growth, leaving a permanent bald spot.
What Is The Difference Between Trimming And Pruning Arborvitae?
Trimming or shearing refers to lightly cutting the outer edges of the soft, new growth to maintain a shape. Pruning is a more selective process involving the removal of specific branches (dead, damaged, crowded) for the plant’s health and structure. Pruning is the more comprehensive term.
How Do You Prune Arborvitae To Promote Growth?
To encourage denser growth, perform light shearing of the new, soft growth in late spring. This prompts the tree to produce more lateral buds just below the cut, resulting in a thicker foliage mass. Also, ensuring the tree has adequate water and nutrients supports healthy growth.