Thatch is a layer of undecomposed stems
and roots that accumulates near the soil surface. Grass
clippings do not contribute to thatch accumulation.
The rate at which thatch accumulates is determined by the type
and vigor of the grass in the lawn. A thatch-prone
bluegrass sod, that is given lots of water and fertilizer,
forms thatch more rapidly than other grasses given less
Thatch is a normal part of any lawn and
only becomes harmful when the thatch layer is thicker than 1/2
inch. When thatch becomes excessive, the lawn may root
into the thatch rather than the soil. Thatch does not
moisture so lawns rooted into thatch will not tolerate dry
weather or cold temperatures. In fact, a very thatchy
lawn can be rolled up just like a rug when it dies out.
Thatch management can take several forms.
The easiest management technique is available
to homeowners with underground sprinklers. A 20 minute
watering at mid-day, every day, helps control thatch by keeping
it wet. Such a watering also is adequate for
watering the lawn.
Three other options are open to homeowners
without underground sprinklers. They are power rakes,
coring and topdressing. Power rakes, or dethatchers, use
power driven tines to tear the thatch out of the lawn.
Much of the lawn gets torn out in the process. While
this is the most common
way to dethatch, it is probably the least desirable. Sections
of very thatchy lawns may need to be reseeded due dethatching
injury. Early September is the best time to use this type
of thatch removal.
A more desirable alternative is coring.
The limitation here is the availability of the coring machines.
Coring machines remove cores of soil and sod. The hole
allows air and moisture to penetrate the thatch and help
A thin layer of soil can be applied over
the lawn to help decompose the thatch layer. This
topdressing may also be combined with coring. The soil
introduces micro- organisms that help decay the
POWER RAKING (DETHATCHING)
A VERY MESSY AND LABOR INTENSIVE
JOB. PRIOR TO PERFORMING THE ACTUAL DETHATCHING OPERATION, MOW
THE YARD AND BAG
THE CLIPPINGS AT LEAST TWICE. THEN POWER RAKE. AFTER POWER
RAKING, THE YARD WILL NEED TO BE VACUUMED TO REMOVE THE
OFFENDING RESIDUE. WHEN FINISHED, UP TO 75% OF THE VEGETATION
WILL BE REMOVED. THIS CAN ONLY BE PERFORMED AFTER THREAT
OF FROST IN EARLY SPRING OR DONE IN EARLY FALLTO PREVENT
PERMANENT DAMAGE TO LAWNS. THE AVERAGE 7,000sq ft SIZE YARD
CAN PRODUCE OVER 1500LBS OF RESIDUE.
If you think you have a thatch problem,
call Green Thumb Lawns Inc. We'll be happy to take a closer look.
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