Even Horties Make Mistakes: Tree Planting

Posted by: Alison O'Connor, Horticulture Agent for Larimer County Extension

This is my linden.  Looks pretty good, huh?  Nice and straight, beautiful canopy.  Was in full bloom a few weeks ago—and I would argue that lindens have the most fragrant flowers in the landscape.  I love this tree and planted it in my yard five years ago, after the Windsor tornado leveled most of my landscape (except for the honeylocust behind it).

[Cue Roberta Flack’s song “Killing Me Softly”]

When you get a little closer, you can see that my perfect tree isn’t so perfect.  Oops.  Sunscald.  I should have remembered to wrap it a little more consistently when it was younger. 

Wait…what’s that?  Is that a…gasp…circling root!? The ones that I preach about in Master Gardener training?  The ones that are known to cause tree failure as they start to girdle the tree?  The ones that can essentially strangle a tree like a boa constrictor?  Nooooooo.
 

So what happens when you have a 4^th of July party and invite other horties over?  They assess your yard.  They start digging around your plants.  They find a massive, 2” thick circling root just below the soil surface of my prized linden.  Uh oh. 

Time for me to investigate and I find the worst.  Not only are the circling roots bad…they are devastating.  To me and the tree.  My husband and I decide to dig out the tree on a Friday night (I know…what a “date”!) and my stomach gets a twisted, sinking feeling as we excavate.  

 

If the first and second offenses were the sunscald and the girdling root, the third offense is that I planted this tree horrifically low.  We’re talking 8” too deep.  I am red-faced and shamed as I write this, as this is the #1 thing I teach when I talk about tree planting.  “Make sure your hole is saucer-shaped and shallow, with the root ball sitting 1-2” above grade.”  I am pretty sure I never said, “Hey!  Dig a huge, deep hole and toss your tree in.”  Wince. (Robert Flack sings, “I felt all flushed with fever; embarrassed by the crowd.”) 

As we dug, I asked my husband, Gil, if he enjoys that every project in the garden ends up being scientific research.  “No, Al.  Not really.”  But…this is so cool!  In a sad, depressing way. 

We got the tree out of the ground and check out the root system.  Remember, this tree has been in for FIVE YEARS.  Does it resemble anything to you?  Does it kind of have a black plastic container-esque look?  

So here’s where I went wrong.  I bought this Greenspire linden at a local nursery.  I didn’t do my due diligence by checking the root system before I planted it.  I obviously should have taken a closer look and either corrected all these circling roots (by washing off or shaving the outer perimeter of the root ball) or selected a different tree.  To be honest, this tree was probably a little large for its container at the time of purchase.  I could have asked more questions, but at the time, I just wanted a tree for my barren landscape.

  There’s been a lot of research on how to deal with trees with circling roots.  Linda Chalker-Scott from Washington State suggests making the tree bare root by washing all the soil off.  While this method may not be practical for those planting dozens of trees, this would have been a great solution for me and my one tree.  Jeff Gillman has looked at shaving the outer periphery of the root ball (removing 1” of soil/roots), shaping the root system into a box.  This had great success in Minnesota.  More importantly, research has found that “scoring” the outer sides is statistically equal to just planting the tree in the ground.  There is also a large study at Michigan State University looking at several planting techniques and an update on the latest findings.   

Woody roots have lots of lignin, making them more difficult to correct once they’ve matured, compared to herbaceous plants.  Teasing and slicing woody roots helps, but doesn’t fix the problem totally (obviously the case with my linden).  Plus tree root balls are large and it becomes cumbersome to try to do this with your hands or knife.   

I don’t know what the final solution is—research is ongoing—but you can guess when it comes time to replant, I’m going to carefully examine and manipulate that root system.  Oh, and find a ruler so I don’t plant the thing too deeply again.  I’m happy I was proactive and removed this tree, since it would have easily become hazardous in the near future (if it wasn’t already).  Those girdling roots cause pressure points at the base and wind in the canopy could have caused the tree to snap.  Did I mention that my neighbor parks his truck just on the other side of the tree?  Girdling roots have been found to be suspect in many tree failures. Want to read more?  The University of Minnesota has an excellent website on all things stem girdling roots.

I’m also glad I removed it, as the next day we had a 30 minute hailstorm that flattened everything.  There was a good chance this tree could have failed then and caused even more damage.  The hail was far more painful to experience than removing my linden…while I technically “killed” a tree, it was for many good reasons. 

Holy hail. 
They had to bring out the snow plows to clear the streets.
Windsor, Colo. August 3, 2013

So the next question is…what should I replant?  A linden?  Ok, will do!  I’ll keep you posted on my next science project.