Planting too deep is a common cause for plant failure.
It’s surprising how sensitive plants
are to being planted too deep. In some cases it
only takes planting just a few inches too
deep to stunt or kill a nice tree or shrub.
There are two main ways deep planting causes the
decline or death of landscape plants. It
suffocates roots and rots the base of the trunk.
Most people don’t realize tree and shrub roots
must have atmospheric oxygen. Roots grow
where there is optimum oxygen. It’s the sudden
change in availability of oxygen that creates a
problem for roots. Plants could have spent months
or years growing roots close to the surface and
then all of a sudden, in a matter of minutes, someone
puts the plant too deep in a hole and covers over
the roots with soil and mulch. It’s somewhat
like putting a pillow over a persons face –
there’s simply not enough oxygen to survive.
The roots slowly suffocate, die and begin to decay.
Weeks or months later, the plant’s owner realizes
something is not right. At this point, they usually
begin looking for a pest.
In addition to root suffocation, the lower part
of the plant’s trunk begins to rot as a result
of
planting too deep. The trunk is supposed to be exposed
to air not covered by soil. As a result, the bark
and wood begin to rot and the plant’s vascular
system becomes compromised – no longer able
to move water and nutrients from the roots to the
top or manufactured food (sugars and starches) from
the leaves to the roots. Again, death is usually
slow.
When planting trees and shrubs, dig a shallow planting
hole as wide as possible. The
depth of the hole should be slightly less than the
height of the root ball. Next, find the point
where the topmost main root emerges from the plant’s
trunk. Because many plants will already be too deep
in the container, you may have to remove the upper
most potting medium before finding one or more main
roots. The main roots I’m referring to will
be comparable in size to some of the plant’s
limbs in diameter. If all you’re finding at
the surface are very small fibrous roots, you’ll
have to keep digging until you uncover at least
one of the main roots. Then set the plant in the
ground so the main root is at the soil surface after
the plant has been planted.
It’s better to err on planting the plant too
shallow verses too deep. Additional information
on this topic is available at http://hort.ifas.ufl.edu/woody/planting.html
Larry Williams, UF/IFAS Extension Agent, Okaloosa
County, September 26, 2007.
