How To Prune Arborvitae ‘Green Giant’

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

161 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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    161 Responses to “How To Prune Arborvitae ‘Green Giant’”

    1. Freddie c Says:

      So i should wait till spring?

    2. Roger Says:

      Freddie,
      I would wait until spring. It’s healthier for the plant, and no real advantage to pruning now.

    3. billy Says:

      Hi,

      Can the green giant be pruned to grow narrower?

    4. Roger Says:

      Billy,
      You can control the plant’s growth to a certain extent and for a limited time. But eventually the plant’s health and appearance will start to decline because of the harsh pruning.

      If you can, transplant the ‘Green Giant’ to a more open space and select a narrower growing variety such as: Arb. ‘Wintergreen’ or Arb. ‘Steeplechase’.

    5. Jim Says:

      I have green giants that are about 4.5 feet tall (planted last spring, although they are growing well, there were damaged branches about 2/3 of the way up which has left a section of nearly a foot that is “bare” all the way around. Howevedr the top and lower half is doing well, but I can’t bear the bare spots, should I top them off? Can they be spliced with a growing shoot? any ideas?

    6. Roger Says:

      Jim,
      At 4.5′ your green giants are very young, so they have tremendous capability to recover.

      I would not top them, but simply prune/trim like I show and describe in the article. By just tipping the ends of branches as you shape the plant, you’ll encourage lateral growth which will fill in those empty spaces.

    7. Jim Says:

      Alright then, that’s the plan. Thanks so much for the reply.

    8. Erik Says:

      I have a staggered row of 10 giant arborvitae that are growing really well. I got them at 8-ft a few years ago and they are already a good 11-ft tall. I really want them wide at the bottom to create a green wall with neighbor. Should I still prune them to keep them fuller, or let them keep filling out? Do I risk them getting leggy if I do t prune them?

    9. Roger Says:

      Erik,
      Yes, you’ll want to keep lightly pruning to encourage a fuller stronger plant. Eventually, it will likely become impractical (if not impossible) to prune — but at that point you’ll have nice, full, strong trees.

      Remember, even just trimming the tips of branches removes the end (apical) bud, which then allows lower, side growth to develop.

    10. Tina Uebler Says:

      I have 2 giant arbs in front of my house, each on one end of the house. When I got them, I had no idea they would get so big! Is there any way to dig them up and relocate them to another part of my property. They are really healthy but they are beginning to become hard to mow around and they are creating an environment for algae on my siding. Thank you for your kind help. Tina Uebler

    11. Roger Says:

      Tina,
      To really give advice on whether your arborvitae can be transplanted I’d have to see the situation. Variables such as: access, proximity to the house, other plants and other structures, etc. come into play.

      Plants of all types and sizes are transplanted regularly, but all the variables have to be considered. And at that, even when transplanting is possible, the cost has to be considered. Sometimes the cost exceeds the value of the plant.

      I would suggest getting a few opinions and estimates from “experienced” plants-people in your area. On this page on my website are articles with more information on transplanting.

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