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Mow Your Grass
Mow the Roots
Trim Your Tree
Trim the Roots
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A customer recently asked me
what was wrong with his lawn. The lawn had large
brownish areas, a lot of those creeping, spreading
weeds that tend to show up in summer, and in
general, the lawn just didn’t look good. It didn’t
take long to provide an answer. He had mowed the
lawn just a day or two previously, so I straightened
my fingers, stuck them down into the lawn to
“measure” the mowing height, and confirmed, as I
expected, that the homeowner was mowing his lawn
quite short—by my measure about an inch in height.
I suggested that the problem with his lawn was that
he was mowing it too short, and that if he just
mowed it at 2 ½ to 3 inches in height, most of his
lawn problems would disappear.
I happened to be in the
neighborhood a couple of weeks later and drove by
the lawn. It looked much greener. I stopped for a
closer look, and it appeared that the lawn had not
been mowed since the earlier visit—it was a little
uneven, but now much taller. The brownish areas
were mostly green, and while those annoying flat
growing weeds could still be found in the lawn, they
were clearly struggling to compete with the now
taller grass. I didn’t know if the homeowner had
actually followed my recommendation regarding mowing
height or just gone on vacation, but the episode was
a reminder to me of the importance of mowing height
to lawn health.
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Previous Articles
A
Loooooong Winter
March 10
Just Dirt
March 18
Horse Manure & Hot Air
March 25
Mulch
to do this Spring
April 01
Creating Long Term
Tree-lationships
April 15
Spring Blooming
Shrubs & Trees
April 22
New
and Improved
Nebraska Arbor Day
April 29
A
Normal Spring
May 6
The Winter of Eight Moons
May 13
Adding Style to your Landscape
May 20
Adding Style to you
Landscape Part 2
May 27
Summer School
June 3
Signature WyoBraska Plants
June 10
It's Time to Fertilize Trees
June 17
A Prairie Garden Walk
June 24
Care of Weather Injured Trees and Shrubs
July 1
What Makes a Good Perennial
July 8
New
Old Flowers
July 22
Grasshopper Control
July 29
Planning Your Fall Landscape
August 5
Viburnums -
A Nebraska Sampler
August 12 August 19
Mow The
Grass-Mow the Roots,
Trim The Tree-Trim the Roots
August 26
2009
Articles
2008 Articles
2007 Articles
2006 Articles
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A few days ago I was doing a
little quick research on lawn water use and ran
across some fairly old University of Nebraska
research on the impact of mowing height on the root
depth of grass plants. I hadn’t seen this research
before. The researchers had mowed plots of typical
lawn grass at varying heights for an extended period
of time, then dug up the grass and measure root
depth. The results were stunning. There was a
direct correlation between the mowing height and the
depth of the roots. In other words, the grass that
was mowed short also had very short or shallow
roots. As the mowing height was increased, the
depth of the roots also increased. Of course,
grass with shorter roots also needs to be watered
more frequently—or it turns brown in the heat of
summer, and grass with shorter roots is also more
vulnerable to insect infestations—because all of the
roots are in one shallow layer. The research made
perfect sense, but also flies in the face of
“conventional wisdom” that mowing a lawn shorter is
good for it—because it makes it “thicken up”. As is
often the case, this “conventional wisdom” about
lawn mowing is not very wise at all.
It turns out that the roots of
trees can also be adversely affected by improper
pruning of a tree’s above ground branches.
Nebraska’s nursery and landscape industry and tree
care professionals began a concerted effort this
past spring to improve the health of trees in our
state’s community, commercial, and home
landscapes. There is a growing national awareness
that trees in these settings are experiencing a
growing list of problems—a particularly disturbing
trend in that they are being produced, planted, and
cared for in what should be almost perfect settings
for growing healthy trees. There is a general
consensus of tree care professionals that many trees
in landscape settings seem to have serious root
system problems.
Two daylong workshops to
identify the problems and explore solutions have
produced many questions—and a few answers. One of
those answers came from another bit of fairly old,
and mostly overlooked, research that found that it
is the low branches of young trees that provide the
food and energy for the root growth of young
trees. The food and energy production of the top
and middle branches generally stays in those areas
of the tree’s crown and is used for branch, leaf,
flower, and seed production in that part of the
tree. This research, again, disputes the
“conventional wisdom” that pruning off the lower
branches of a young tree stimulates it to grow
taller faster. In reality, it appears that pruning
off the lower branches of young trees significantly
reduces the rate of growth and development of its
root system—and by extension, slows down its top
growth as well.
At this point I know of no
revised tree pruning guidelines that reflect this
research, but I suspect that those new guidelines
will be forthcoming soon. In the meantime, I
suggest using caution when “pruning up” young
trees—and don’t prune lower branches on young trees
until absolutely necessary.
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