10 Tree Facts That May Not Be True

As an arborist, I have been told and sometimes asked about tree facts that I’ve learned may not actually be true.  I won’t cite any references to back up my claims, but here are just a few I believe to be false.

1. It is against the law to remove a dogwood tree in Virginia.

• I have never seen nor can I find any evidence that this is true, yet for my entire career I have been asked this question.

2. Walnut trees are allelopathic and kill plants under their canopy.

• I am not going to explain this one. Instead I offer this link to disprove this “fact” that everyone seems to think is true.

3. When planting trees, the planting holes should be very deep.
   • Planting holes should only be as deep as the bottom of the plant container to the root flare of the tree. The root flare should be present when you are done planting. The planting hole should be wide; the plant hole should be at least 3 times the diameter of the root ball.

4. A heavy acorn crop means we’ll have a long winter.
   • I don’t think I heard this in college, but I have heard it my entire career. The story is it’s going to be a long winter, so the trees are producing a lot of extra acorns for the wildlife. It seems to me that the crop production of acorns is more from past weather experiences on the tree.

5. Tree roots on the surface of the lawn are a result of the tree species.
   • In my experience, the reason the roots are on the surface of the ground is because there are poor soil conditions like compaction, high water table, or lack of oxygen.

6. Trees need to be staked after planting.
   • I have staked trees because the tree after being planted was unstable due to a heavy canopy and a small root ball, but most of the trees I have planted did not need to be staked.  As the trees move in the wind they will grow roots to help stabilize the tree. 

7. Trees need to be fed.
   • Trees feed themselves by taking in carbon dioxide, water and sunlight and nutrients from the soil and convert it to sugars for tree growth. This process is called photosynthesis.

8. Tree roots break sewer lines and foundations.
   • It is true that you can find tree roots in sewer lines and foundations, but it ‘s not true that this was caused by the tree’s roots. Tree roots are looking for water and nutrients and when they see an opportunity they take it. From what I’ve seen, the sewer line or foundation was already broken and the roots simply found their way in.

9. Tree wounds or pruning cuts should be painted. 
   • This one is less common these days, but I am still asked this often. Painting a tree wound or pruning cut can actually increase decay in a tree by increasing moisture in the tree.

10.  Tree roots are a mirror image of the tree’s canopy.
    • Tree roots are usually not much deeper than 18” deep and can spread out 3 times the height of a tree.  It was explained to me that it is like a wine glass on an upside down plate. The plate represents the roots, the stem of the wine glass is the trunk of the tree and the cup on the glass is the tree’s canopy.