How To Prune Arborvitae ‘Green Giant’

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

174 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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    174 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.

    12. Pavel Says:

      Roger, thank you for your article! I planted 30 of 9-10ft ones 2 weeks ago and I planted them in a row 3 ft apart and 2-3 ft from my fresh poured concrete driveway. Besides, there is a gas pipe 4-5 ft below them. Unfortunately, I didn’t do my research before I’ve planted them and didn’t realize they are going to become so huge in a while.
      My concern is that I placed them way too close to my driveway and that the gas pipe beneath. Besides, my initial plan was to keep them no higher than 15-20ft but I didn’t realize what I was buying :-(

      Options I think about are:

      1 . Remove them and plant something else (don’t really like the idea for many reasons)

      2. Move them further from the driveway(max. I can move them is 4 ft from the concrete edge) but that gas pipe is still beneath. Also, I can space them 4 ft apart to give them more space to grow.

      3. Leave them as is and keep pruning them to make sure they don’t grow bigger than 15×6 ft wall
      and, hopefully, it will keep the roots from spreading that much to damage the driveway and the pipe.

      here it is the youtube link to show how it all looks at the moment
      https://www.youtube.com/watch?v=plEyaDcZX6o

      thank you for your advice!

    13. Roger Says:

      Pavel,
      Based on what you’ve written and the YT video, I would work along the lines of your #2 option, including changing/increasing the spacing to 4′ apart. You’ll still need to diligently monitor and prune the ‘Green Giants’ to keep them within bounds (both height & width).

      If the gas line is 4-5 ft down, you should be OK.

    14. Denise Says:

      I have 20 green giants planted along a fence line. We planted them 4 ft apart and 4ft off the fence about three years ago. They are spot 6 ft tall as of now. As instructed by the nursery, we have been trimming the leader in early spring to encourage a fuller tree.
      We are hoping to maintain a thick square green wall with these trees. Will we be able to keep pruning the top and sides to shape them?
      Would you advise not cutting the leader next year to encourage the top to grow and not so much the sides?

    15. Roger Says:

      Denise,
      Green Giant, as you know, has the ability to get large fast. You’ll need to continue to keep this plant under control by pruning — including the top leader. You’ll still be able to allow it to grow each year (to your vision) even though you’re pruning it to keep it “in-check”.

      You have an advantage here in that you are aware of its potential. Most folks either are not aware or simply don’t pay attention — at which point the plant outgrows the space.

    16. Heather Says:

      Hi! My neighbor planted 40 of these 1′ off our property line; despite my attempt to educate them about the ultimate size of these….. Anyway, they’ve reached about 7′ high and encroached onto my side by 3 feet at this point (no surprise). How do you suggest I prune these monsters – shearing or further down the branch? And we are considering a privacy fence to push back the growth (150′ of pruning is not in my annual plans) but will they take out the fence – their side is the sun side…. Thanks!

    17. Roger Says:

      Heather,
      This kind of thing happens a lot. And if yard space is “precious,” you’ll want to do everything you can from day one to preserve it.

      The fence is a good idea. Keep in mind that fences with wood posts eventually rot where the posts meet the ground. This will allow any pressure from the growing arborvitae to push over the fence. Ideally you want to choose a fence (or a least the posts) that do not rot.

      Also, realize that the fence will help contain the arborvitae to the height of the fence. After that the plant’s growth will continue over on to your property.

      I think your best course of action is to go with a strong fence, and then an annual trimming regimen that “shears” the arborvitae back to the fence line. Notice I said “shear,” not prune. It’s unrealistic to think you could selectively prune all these arborvitae. The key here is to start early on, before they really encroach over the fence.

      The tools to consider would be a power trimmer and/or a telescopic power trimmer.

    18. AJ Says:

      Hi
      I planted 40 green giants on my property to have a live fence in May 2016
      Unfortunately a few of these thinned out at bottom even though the trees were strong and healthy.
      This summer even after all the new growth they put out, the lower part of these trees did not thicken out much. My trees were 6 feet tall last year and this year they added aroud 3 to 4 feet.
      I read on internet that cutting back on central leader and top growth areas will encourage a tree to thicken out at bottom. As a result I cut back the central leader by around a feet but now I am worried that I have damaged the tree because of this. Will I have to now train a branch to become central leader? If yes, will this not structurally damage the tree as the trunk for ever will be a little rounded instead of being straight?
      The trees are healthy overall and get full sun. I am in NJ zone 7A.
      Please advise.
      Thank you

    19. Roger Says:

      AJ,
      If you removed only one foot of the leader you should be fine. The arborvitae should continue to grow with one, strong central leader.

      Overall this is a good strategy to encourage a fuller plant. And since the lower portion of the plants are weaker, this is really the solution to improving that.

    20. AJ Says:

      Thank you so much for the information.

    21. John butrico Says:

      I cut down the central leader of green giant arborvitae that were growing too tall. Does that mean they will no longer grow from the middle where cut? I feel i may have made a mistake.

    22. Roger Says:

      John,
      How the plant(s) will grow after your pruning depends on how much of the central leader you cut. If you cut a minimal amount, such as 6″ or so, the plant will continue to grow with “that” central leader. If you’ve cut a considerable amount (and it’s hard to say what that is w/o seeing the plants) then the arborvitae will have several, top lateral branches that will push growth out their ends. In this case, and if you want to re-establish a central leader, you’ll need to do some selective pruning to gradually encourage one of those top, lateral branches to assume the role of central leader.

    23. Ken Says:

      Hello. I live on a pie shop lot my neighbor has the same. I planted 25 emerald green arboro 5 years ago on a fence line that did not do well in the back of our property for privacy. We both agreed to rip them out and replace with green giants. Placing then 5 ft apart I come up with 12 needed to plant

      I am worried about the size the giant will get down the road. Area is tight. Is it better to plant 6 on my side and stager 6 on their side evenly spaced to control size better ? Or plant them on my side in a straight line as my emerald greens are now . I am more worried about width

    24. Roger Says:

      Ken,
      Planting 6 on your side and 6 on your neighbor’s (staggered) is better for the plants, but the 6 on your side will ultimately take up the space you’re concerned about. Can you plant right on the property line? I’ve had homeowners do that — and often they’re splitting the cost of the planting too.

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