For All You Timid Root-Pruners Out There

I regularly cause a lot of anxiety by how drastically I root-prune newly collected trees.  To be sure, it takes some courage to start really chopping on your deciduous trees the way they need to be, but once you figure out they don’t mind it does get a lot easier.

This Bald cypress (Taxodium distichum) a client bought last fall, which surprised me the other day by starting to pop buds all over, is actually a different case in that it’s been container grown to size.  My bonsai friend and sometimes supplier Bill grew this tree from a young seedling, developing the trunk by the grow and chop method.  He did an awesome job of creating taper.

But the roots, man oh man, he actually got them to buttress in the growing container by keeping the tree’s roots submerged in water all the time.  It’s a technique I plan to try myself.  Notice how deep the growing container is.  And notice how the roots have burst through the container.  When I got it from Bill, he had the whole tree stuck in a 5-gallon bucket.  I knew I had a root-pruning job ahead of me.  With the tree popping buds, I had to take care of this today.



The first step was easy – just saw off what won’t be needed.  I went ahead and took it down to about how deep the eventual bonsai container will be.  There’s no point in leaving thick roots that will have to be chopped again down the road.













The rest of the container removed.  The roots have conformed themselves to the shape of the container.















Container-grown trees always produce coiling roots; in fact, you’ll see many container-grown trees, and Bald cypress is one of the worst, that have really horrible-looking roots owing to this phenomenon.  I believe that Bill’s technique of growing the tree in a very deep but not too wide container, and keeping it submerged, prevented this problem from happening.









Here’s the shot that is sure to make some folks cringe.  There’s just not much left of the root mass, now is there?  But this is all that’s needed.  If you’ll look closely at the third photo above, you’ll notice one very interesting fact: there are no nice fresh white feeder roots.  It’s not time for them to begin growing yet.  BCs push foliar growth first, whether on a newly collected tree or a container-grown tree.  Once the shoots start pushing, that’s when the new root growth begins.  This probably won’t happen for another couple of weeks.  But I’m taking advantage of the habits of the species to go ahead and do this necessary work now.






And finally, the tree in its new (temporary) home.  The pot is only a 3-gallon, but it’s plenty since no further trunk thickening or taper building is required.  All of the branch work can be done starting from here.

The base of this tree is 3.5″ across, 3.5″ above the soil surface.  It’s chopped at 22″, and should finish at about 28-30″.  The buttressing is very uncommon for a tree this size.

Let me know what you think.  And are you chopping your roots hard enough?

10 Replies to “For All You Timid Root-Pruners Out There”

    • Zach Smith Post author

      No, the tree “wants” to live so it will produce new roots. This is really no different that when we root-prune our bonsai. Removing a third or more of the root mass of a bonsai effectively removes all the feeder roots, yet the bonsai does not die from this procedure.

  1. Terry

    Zach,I’m getting excited to Work on on my trees, but I have 6″ of snow on the ground! Should be soon though. What’s the best soil mix to repot these in? I have the BC that I purchased from you last year that I will repot as soon as the buds show.

    • Zach Smith Post author

      Terry, I use a 50:50 mix of pine bark mulch from Home Depot and expanded shale (Haydite/Riverlite/Turface, 3/16″ grade), unscreened for nursery stock and screened for bonsai.

  2. Ken S

    Hi Zach,
    I live in zone 6 where temps are still below freezing. My trees are stored in my garage at temps between 30 – 40 degrees F. If I want to get started repotting some of my bald cypress, is it necessary to keep my repotted trees with their newly pruned roots away from freezing temps?

    • Zach Smith Post author

      Ken, you should follow the usual guidelines when protecting trees whose roots are newly pruned – keep protected when it goes below about 25. The danger comes when the tree begins producing tender new roots. It’s at that point that a lot of root damage can occur as spring nears. For Bald cypress, it’ll take a while before you get tender new roots so use budding as a gauge. Once buds start pushing and become shoots, count on root growth to begin in two or three weeks. Protect accordingly.

  3. Jeff

    Hello Zach, I really enjoy reading and learning from your posts. I’m not sure if anyone has mentioned it but when viewing from my mobile device the Facebook, Twitter, Pinterest pop up always covers the image.


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