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How roots really
grow
Root excavation
Deep root feeding
Improper fertilizer placement |
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Tree Basics -
the root of most tree problems
 Out of sight...out of mind
Many
people
still believe tree roots grow deep and extend only to the drip
line. We now know roots do not grow that way. |
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But continuing
research has demonstrated time and again that most tree
 roots are in the top 18
inches of soil. And tree roots extend far out beyond the drip line usually
about as far as the tree is tall. Feeder roots are shallow because living
roots require oxygen as well as moisture.
Understanding where roots are and
the roots' need for oxygen can help us properly protect trees during
construction.
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Root Excavation
The Air Spade is a non-invasive tool that removes soil without damaging
roots, even fine fibrous roots. An Air Knife is a similar product made by
another manufacturer. These are some of the treatments possible
with the Air Spade:
 | locate and remove circling (strangling) roots |
| remove buried straps, fabric or wire baskets |
| correct problems caused by trees planted too deep |
| aerate compacted soils |
| inspect and remedy construction damage to roots |
| make a trench for irrigation pipes that won't sever
important roots |
| analyze and correct roots interfering with structures |
| root tracing to determine the precise location of major roots
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An Air Spade using supersonic air to remove
soil from tree roots with negligible impact on the roots.
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| Root tracing is one technique which
safely determines the exact location of major tree roots so construction
activities can be kept away from these important roots. Soil is blown back
over the roots at the end of the procedure. The concentric, regular layout
of the roots shown (right) is rare. Usually root growth is more irregular
and random. |
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Deep Root Feeding
Sounds like a great idea, but...
If most of a tree's feeder roots are located in the top 12 to 18 inches of
soil, why would anyone want to inject fertilizer 24 to 36 inches below the
soil surface? This practice not only wastes your money but also can deposit
fertilizer components, which are pollutants, into ground water. |
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Ring Around the Root Collar
Tree roots spread out from the trunk into the landscape.
Putting a heavy dose of fertilizer around the base of
a tree wastes fertilizer. Furthermore, fertilizer is a salt
and can burn tender tree feeder roots. The application shown in the photo
was made by the crew of a national landscape
maintenance company. |
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