Does My Lawn Need a Dethatcher?:
Seven Frequently Asked Questions
Not as commonly known as other
lawn care tools, a dethatcher or power rake looks similar to a lawn mower but has
several vertical spinning blades that slice into the thatch layer while
pulling some material to the surface. Since dethatching should only
be done as needed and they are rather expensive to buy ($1000-$2000),
it makes more sense to rent one or hire a professional when your lawn
needs to be dethatched.
What is thatch?
Thatch is a naturally occurring
layer of interconnected dead and living stems, leaves, clippings, roots
and debris found between growing grass and the soil under it.
Why does thatch develop?
A high-maintenance lawn tends
to have more quickly developing thatch than a low-maintenance one. Compaction,
high acidity, unbalanced fertilization, overuse of fungicides/insecticides,
and improper care (never aerated, not mowed frequently, too much mulch)
can also increase thatch growth.
How does thatch affect my lawn?
A normal amount of thatch improves
turf resiliency when faced with heavy use, drought or high heat because
it will hold in extra moisture and shield the soil from the sun. But
if it gets thicker than an inch, it impedes the ability of water, fertilizer,
air and other nutrients to get to the roots. If thatch dries out, it
will decrease the drought resistance of the grass, and if it stays wet,
fungi and disease may grow there, which will be hard on grass already
declining because of poor access to water and nutrients. A thick layer
of thatch makes the lawn more susceptible to pests, unfavorable weather
and weeds while also decreasing the effectiveness of regular care and
maintenance.
How can I tell if the thatch
is too thick?
To determine if there is too
much thatch, cut a small, deep plug of grass and dirt and examine the
spongy layer above the soil. If it is more than one inch thick, it is
time to dethatch the lawn. If it is between 1/2 – 1 inch, it is a
good idea to consider dethatching soon.
How do I remove the thatch?
At this point, a power dethatcher
will do the best job of removing the thatch. Mechanical lawn dethatchers
are best used during cool weather in the fall or early spring when the
soil is not too wet. You want the grass to have time to recover before
the weather gets adverse.
How do I use a power dethatcher?
Before using a lawn dethatcher,
mow the grass to half its normal height. You can hire a professional
or rent a power dethatcher to do it yourself. They cost around $60 to
rent for half-a-day or four hours, which should be long enough to do
the majority of residential lawns. At the rental company, have them
help you set the depth and blade spacing. You want the blades to cut
about ½ inch into the ground. Blades should be spaced about 1-2 inches
apart for warm season grasses that tend to be tougher and around 3 inches
for the thinner, more delicate cool season grasses. Go over the grass
with crossing patterns for the best results. Do not try to remove all
the thatch at one time.
What do I do after dethatching?
After dethatching, it is best
overseed to help fill sparse areas. Many lawns will not look great for
2-3 weeks after, but then will look better than they did before. Topdressing
with a thin layer of topsoil (around 1/8 inch) like the dirt under the
grass is not necessary but can improve the lawn condition. Be sure to
water well. Other ways to reduce thatch build-up include reducing nitrogen
fertilization, adding proper soil amendments, frequent mowing, and leaving
mowed clippings on the lawn (only if they are not too long since if
they do not decompose quickly they will turn into thatch).
Looking for a dethatching rake?