Tree Planting No-No's!

Posted by:  Amy Lentz, Weld County Extension

It’s planting season all across Colorado, from agricultural crops to flowers to trees. It’s the latter that I want to address today in this blog…planting trees! Our towns and cities are growing (fast!) and with this comes the planting of a LOT of new trees, both in public spaces and on private property. Planting trees in the correct manner is the most beneficial thing you can do for a tree’s health as it will be the foundation of the tree for the rest of its life. If these newly planted trees start off at a disadvantage, it could invite many insect, disease and other tree health issues down the road. And let’s be real, trees are not cheap! They are quite an investment that will eventually pay off down the road once the tree matures…if it’s been properly planted and cared for as it gets established.

Being a tree in Colorado isn’t all that easy with our dry climate, wide swings in temperature and less than ideal soils in most locations (among other hurdles). This makes it ultra-important to help these newly planted trees get off to a good start in life. If planted incorrectly, these trees can be doomed with a death sentence from the day they go in the ground, but you won’t see it right away. In many cases, a poorly planted tree will not show symptoms of poor planting until a few years later.

Here’s my list of 5 Tree Planting No-No’s:

1. DO NOT DIG THE HOLE TOO DEEP.

You should plant the tree so the root flare (where the tree’s trunk meets the top of the roots or the top of the root ball) sits just slightly above the existing soil level, 1 to 2 inches. Measure the root ball before you start digging and check the depth periodically as you go down. You can always remove more soil if the hole is too shallow, but soil that has been added back into the planting hole will not act the same as if it were not disturbed. Instead, it will settle and the tree will likely sink causing it to be planted too deep.

2. DO NOT DIG THE HOLE TOO NARROW, MAKE IT WIDE.

The hole should be 3 times the width of the root ball of the tree and have sloping sides. This is especially true for trees grown in containers, as their roots need to adjust from growing in a barky potting mix to growing in heavy soils. Digging the hole wider will loosen the soil so the roots can grow and adjust more easily to the native soil.

3. REMOVE ANY TYPE OF TREE BASKET! 

This tree was easily pulled from the ground years after it was planted. It had a very poor root system due to the wire basket being left in place at planting. A Big No-No!
.

I can’t stress this enough. I have seen trees succumb to a slow and horrifying death because wire baskets have been left in place. Not only is the tree you've invested in dead after a few years, you have also lost years of growth and will have to start over. Burlap and rope should also be removed as these will not break down fast enough in our Colorado soils, hindering the root growth of the tree and causing the same demise. So take the time to remove the basket and place the tree gently into the planting hole. This is also a good time to check for circling roots or roots growing across the base of the trunk and direct them away from the base of the tree.

4. SAY NO TO MULCH VOLCANOES. 

Just say no!

I have seen a lot of this lately! Trees take up water and nutrients from their roots, not their trunks. Therefore, the trunk does not need mulch to help conserve water or protect the tree. Instead, it hurts the tree. Having mulch piled up around the base of a tree can lead to the wood rotting and inviting pests and disease to attack the base of the tree. Don't get me wrong...mulch is a great thing! I love seeing trees with good-sized mulch rings underneath as this creates a favorable environment for the tree’s roots and keeps mowers and string trimmers away from the tree. So use mulch, just use it in a 2-3 inch layer out to the drip line for a new tree, keeping it a few inches away from the base of the trunk.

5. DON’T STAKE YOUR TREE TOO TIGHTLY.

Too tight.

Just right.

A newly planted tree needs encouragement to grow strong roots. Think of it like an arm in a cast…without the ability or need to move the muscles, they become weak. If we baby a newly planted tree too much by tightening the staking straps to the point of no movement, the tree will not form as strong of a root system because it doesn’t have to in order to remain upright. Staking straps should have a little wiggle room so the tree can still sway in the wind. Furthermore, if they are too tight, they could girdle the tree’s trunk as it grows in size. Straps should only be left on for the first year a tree is in the ground.

There are many other helpful recommendations when it comes to planting trees. For the complete story, check out the following resources from CSU:

Tree Planting Steps - Colorado Master Gardener Garden Note #636

The Science of Planting Trees - Colorado Master Gardener Garden Note #633

Stem Girdling Roots

There have been a couple previous blog posts on dysfunctional tree root systems but we have had a number of really good examples of trees with stem girdling roots come through our office this spring so I thought I would share some pictures of the issue.

A normal root system will grow outward from the trunk of a tree in a radial pattern that resembles the spokes of a wheel (though it will not be as uniform).  There is also normally a pronounced outward flaring of a tree’s trunk where it meets its root system. 

 Due to some nursery stock production techniques and planting practices some landscape trees develop roots which do not grow radially out from their trunks but instead grow across or around them.  

A root of this container grown oak deflected upward when it contacted the container, grew to the surface and then across the surface of the container .  When it reached the other side of the container it then began to circle. If left uncorrected such roots can become girdling roots.

The same tree also was planted deep in the container, ~4 inches of soil was removed from the top of its root ball before I found its first structural root.  

Such roots have the potential to become ingrown into the trunk as they both grow.  This interferes with the tree's vascular system which becomes compressed where it presses up against the offending root.  In cases where the root is circling and wrapped around the trunk the tree may be girdled.

Major stem girdling root on a littleleaf linden

 

Stem girdling root on the same linden  cut in preparation for removal. 

The root has been removed, note the compressed tissues of the trunk.

Deeply ingrown stem girdling root on a horsechestnut.  We were unable to remove this root but be were able to cut it at either end to stop it from growing further.

Exposed stem girdling root on an autumn blaze maple

Trees which develop stem girdling roots may have reduced vigor, slower growth, be more prone to lean and fail and are more susceptible to a variety of stresses.   Severe cases can lead to decline and death.

Swamp white oak with dieback, little growth and chlorosis 

A root collar excavation revealed the tree was planted deeply and had several stem girdling roots.
The root flare should be mostly above grade and visible.

Close up of  partially ingrown stem girdling root on the above swamp white oak

Austrian pine with leaf scorch and very slow growth. We found several major girdling roots. 

Stem girdling roots on the above pine

Ingrown stem girdling root on the other side of the trunk of the  above pine

Cottonwood which failed above a stem girdling root.

Close up of Cottonwood which failed above a girdling root.

So what can you do to prevent these issues and encourage a normal root system? 

1)When planting a tree, make sure the root flare is exposed by removing any soil or potting media covering it.
2)Plant the tree with its root flare slightly above grade.  The first structural root should be in the top couple inches of the tree’s root ball or at its surface.
3)If the tree has circling roots remove them at planting.  Shaving or boxing the root ball is a good way to do this.


"Boxing" a trees rot ball at planting to remove circling roots.

4)Dig a large planting hole which has a saucer shape.
5)Inspect the tree’s root flare regularly and remove any potential girdling roots before they become ingrown.

Moving Large Trees at the Plant Environmental Research Center.

Posted by: Eric Hammond, Adams County Extension

Late month many of the more unique trees planted around the perennial demonstration garden at the Plant Environmental Research Center (PERC) on campus at CSU were moved via tree spade to new locations.   The gardens and the trees are being moved to make way for several practices fields which are going to be installed alongside the new stadium on campus.  In all 19 trees were moved including several very large trees which required a 120 inch wide spade.  It was pretty interesting to watch and I thought I would share some pictures and videos of the move.

120 inch tree spade which was used to move the largest of the tree salvaged from PERC.  Larger trees require larger spades in order to dig a large enough portion of their root system for successful transplant.

A slightly smaller tree spade also used in the project.

A slightly smaller spade preparing to dig a linden.

When an established tree is moved with a spade a large portion of its root system and a particularly large proportion of its fine feeder roots are left behind.  This means spaded trees need to be watered diligently for several growing season after they are transplanted.  Water should be applied relatively more frequently with relatively smaller amounts of water compared to an established tree to keep the tree's root system moist without creating a pond at the bottom of hole created by the spade.  

Severed roots can be seen along the side of the hole left by a tree spade circled in red.  A large portion of an established tree's root system is left behind when it is moved with a tree spade. 

It can take a number of years for a spaded tree to establish its root system after transplant and until they do canopy growth is often limited.  Staking recently moved trees is often advisable due to their reduced root system.

Hole left after a tree was lifted with a tree spade.

Here is a sequence of photos and videos of a large upright European hornbeam being moved (thanks to Josh Lambright for the videos):

Digging the hole for transplant.

A upright European hornbeam being dug with the 120 inch spade.

A large spruce being set in place at its new location

Close up of the "root ball" brought with the tree.  The tree root system was likely 2 to 5 times the width of its canopy before transplant.

  

Large upright European hornbeam after transplant.

The Fourth Ginkgo

Posted by: Alison O’Connor, Larimer County Extension

Sometimes I feel like my green thumb has turned brown. Especially when I spend another weekend working in the yard, witnessing the death and destruction of my garden. In my defense, we did have a devastating hail storm that occurred last August, but it also seemed like winter took a deadly toll on my plants.

Including my ginkgo. That was the third one I had planted since we moved to our house in 2007. The first two had really poor root balls (they were a “deal” at a tree sale) and only lived for one season each, and the third was in bad shape when it came to my yard. I will say, however, #3 lived for two whole growing seasons!

As I was sighing in my yard, I inspected all my trees. All my trees are pretty small. Besides the hail storm last summer, we also were in the throes of the tornado that struck Windsor in May 2008. Except for a mature honeylocust and silver maple, all my trees are just juveniles. Here’s a look:

The mature honeylocust (Gleditsia triacanthos inermis)

The mature sliver maple (Acer saccharinum)

'Guinevere' crabapple. She's my favorite tree in the yard.
Small, cute and blooms pink! What more could you want in a tree?

'Greenspire' linden. You saw me plant this one just a few weeks ago.

Redbud (Cercis canadensis). It lived! I'll admit that I'm a bit surprised.

And it's starting to leaf out!

Thornless cockspur hawthorn (Crataegus crusgalli inermis).
Dark green, glossy leaves and red fruit that spills on the ground in fall.

'Honeycrisp' apple. Yep, it's teensy tiny. Maybe I'll get fruit in a few years.

Some type of plum I don't care about. It bears prolific fruit, which the beagles enjoy.

And my newest edition: ginkgo #4. Yes, I bought another ginkgo.  

My beloved ginkgo (Ginkgo biloba)!

Prior to tree shopping, my husband and I had this conversation...

Me: Gil, I’m going to look for a new tree for our yard. Do you have any suggestions?

Gil: Maybe something that will live? How about a buckeye?

Me: That’s not a bad idea! I like buckeyes. They are tough as nails.

Gil: Plus, maybe it will help them win the National Championship?

(We are both Ohio State grads.)

Me: Hmmmmm.

But then I got to the nursery and I immediately asked the first employee I saw where their ginkgoes were located. She showed me. I wooed. I fell in love and I brought #4 home.

The leaves! The fan-shaped leaves are emerging! Love love love.

Gil: What!? Another gingko? Are you crazy?

Yes. Yes, I am. Because the ginkgo is my favorite tree in the world—it’s a living fossil! And I have.to.have.one. The fourth time is the charm. Right? I know that they are difficult to establish. I know they grow slower than molasses. I know all of this…but I still have to have one. I need to have one. My yard needs a ginkgo.

So tell me, what plant did you have to have and purchased over and over again? Did it finally work out, or did you give up and plant your version of a buckeye? 

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.