How To Prune Arborvitae ‘Green Giant’

How-To's, Landscape Care · Written by Roger

59 Comments

shear.arb.ggThe Green Giant’s Growth Habit

Perhaps I’ve said it before, but it’s extremely helpful when you know what a plant’s growth habit is before you prune.  Growth habit is basically the shape a plant naturally wants to grow into and how the branching structure supports that shape.  For example: Arborvitae ‘Green Giant’ is pyramidal in form and proportionately much taller than wide.  As a matter of fact, this plant will easily get to 30′ tall and 15′ wide in thirty years.  Rapid grower…I think so.  Its branching structure is horizontal with some ascending branches as well.

Other characteristics about the plant can be helpful too when deciding your pruning strategy.  For instance, Arborvitae ‘Green Giant’ prefers more light (full sun is ideal).   The less light it gets the thinner and more open its branching and foliage will be.  Prune less aggressively if you know the plant is adapting to less than ideal conditions.

Before Pruning

The Pruning Strategy

Let’s assume the ‘Green Giant’ you’re going to prune has been positioned to have enough room to grow and stay somewhat within its “natural boundaries”.  If the space is too limited and there’s no future for the plant in that spot, think about transplanting it.

To give ‘Green Giant’ a strong trunk and branching structure, it’s important to prune them in their early years.  In the first picture above, these Arbs were undoubtedly pruned early on in their lives.  Notice how full they are from the ground to about 4/5ths of their height.  However, the last growth at the top is thin and “stretched-out”.  This is very typical of rapid-growth plants.

It is this top growth (upper 1/5th) that needs pruning.  You should also scout the lower portion of the plant for any branch ends that may have grown more aggressively than others.  There should not be many.

After Pruning

I apologize for the picture quality of these “before” and “after” shots, but even the silhouette conveys the degree of pruning I did.

I used a traditional trimming shear along with an orchard ladder.  By today’s standards you might call that “old school”.  I still think a good quality hand shear gives the best cut and, of course, with total control.  I did, however, think how convenient and productive a telescopic gas powered shear would have been.  Just take care as those power shears can cut aggressively.

The main goal and concept here is to trim the ends of the longer, fast growing branches to shape the plant and encourage fuller growth.

This is what plant nurseries do while they’re growing the plants for market.  You want to continue this trimming routine for as long as it is practical.  The idea is to develop a full, nicely shaped plant so that it can continue to grow on its own with this strong foundation you’ve help create.

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    59 Responses to “How To Prune Arborvitae ‘Green Giant’”

    1. Mike K Says:

      I have what was 2 great trees that took a beating this winter
      Can the trees be that are over 20′ be trimmed down to about 8′ and live ?

    2. Roger Says:

      Jessica, that should be fine. Often we can’t reach the tops to be so precise with our cuts either. The plants will continue to push new growth and maintain a leader.

    3. Paul Tomczak Says:

      I ordered Emerald Greens from a mail order nursery years ago and was very happy with the plants, although they were subject to scale on occasion. I’ve been looking around at local nurseries for additional plants, but the Emerald Greens don’t quite match what I received by mail. The local plants all have branches that are oriented to the vertical, whereas my Emerald Greens have branches that are more horizontal, giving a sculpted look that I prefer. Are there different varieties of Emerald Green? Thanks!

    4. Roger Says:

      Tammy,
      Arborvitae prefer a neutral pH soil. Plant-tone would be great.

    5. Roger Says:

      Brian,
      You could prune the top leader back to a certain point. It’s hard to give a definitive amount to cut back because situations vary. But think in terms of always maintaining a pyramidal form. So prune the top (crown) as a whole and see how the aggressive shaping at the top (maintain the leader and pyramidal form) allow you to cut back the leader’s height. I hope that makes sense. I really have to start doing simple videos to demonstrate things like this.

    6. Roger Says:

      Richard,
      Tough to tell without seeing it. You’ll have to wait and see – so hold-off on any corrective pruning till the season progresses and you clearly see what’s living and what’s not.

      The plant can push new buds and growth in some circumstances. However, any stems or branches that had their bark stripped off will likely die back. This outer layer (cambium) transports nutrients, and when it’s removed that causes that section of the plant to die.

      It’s those portions of the plant with bark remaining where it’s possible to re-bud.

    7. Roger Says:

      Mary,
      Interesting. In our area ‘Green Giant’ is called deer resistant. This is just another example that “deer resistant” plant lists should be taken with a grain of salt. And just the other day I had a long conversation with a person who operates a deer control business. And he was telling me of many instances where deer were behaving differently than industry reports & lists were stating. In short, it’s not an exact science by any means.

      To answer your question, yes, you can elevate the trees to remove the damaged lower branches. The tree will be fine. And actually, it can look quite nice.

    8. Roger Says:

      Mike,
      The trees must be in really bad shape to have to cut them back to 8′.

      Without seeing the trees it’s hard to even comment, but this is my thought: If you’re cutting them back from 20 to 8′, I have to believe the tree is not only compromised health wise, but disfigured too. Perhaps you should think about replacing them. At least the new plants (at 8′) will be attractive, healthy and ready to grow.

    9. Roger Says:

      Paul,
      I feel your pain. I too have experienced variations in plants when they are labeled the same. I can’t say for sure why this happens, but it’s not uncommon.

      Trust your judgement and wait till you find the leaf type and habit of growth that resembles the euonymus you have (and like). It’s great that you’re that observant.

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