Q.
What do you
recommend to control moss in a lawn? I have used a product
called Scott's Moss Control and have applied limestone with
little or no success.
A:
Moss can be difficult to control. It is important to find and
correct the underlying factors that have created such a
favorable environment for the moss or else it will grow back
quickly, as you have found. Correcting those problems will allow
the grass to outcompete the moss.
Conditions that favor the growth of moss include excessive
moisture, heavy shade, compacted soil, poor soil fertility and
low soil pH.
Start by having your
soil tested.
Test kits available from your county extension office come with
instructions for taking a good representative sample. Do
separate tests for lawns, flowerbeds and/or vegetable gardens.
If you have lawn areas that are very different -- one heavily
shaded by mature trees vs. an open lawn in full sun -- have them
tested separately. The results should come back in 10 to 14 days
and will tell you exactly how much limestone and fertilizer to
apply to correct the soil pH and improve soil fertility. To
order a kit from the Penn State Extension of Allegheny County,
see the end of this column.
If the area stays constantly moist, it will be very difficult to
get ahead of the moss. You may need to install French drains to
move water away from the area, redirect downspouts or take other
steps to improve drainage. If improving drainage requires
re-grading the area, be very careful around existing trees. A
few inches of additional soil over a tree's root system can
cause it to decline and may kill it completely. Roots cannot get
sufficient oxygen if they are buried under too much soil.
If the area stays moist because of dense shade from mature
trees, consider hiring a certified arborist to remove some of
the lower limbs and thin dense canopies. Allowing more sun
exposure and increasing air circulation will help the area dry
faster after rainfall. Also, more sun will create a better
environment for grass to grow. Even shade-tolerant varieties do
best with some sun.
You can alleviate mild soil compaction with
core aeration
prior to applying limestone and fertilizer as recommended by
your soil test. A core aerator is a machine that pulls out plugs
of soil 3 to 4 inches long. The holes left behind promote better
soil aerification. Better soil aerification creates a more
favorable environment for the development of a strong root
system for the grass. Also, some of the limestone and fertilizer
will filter down into those holes, affecting the change in soil
pH and fertility where the grass roots live.
Type of Lawn
Finally, the
species of turfgrass is important because most do not perform
well in shade.
Fine
fescues do well in shady, well-drained areas. Rough
bluegrass (Poa trivialis) tolerates shady, moist areas.
Be aware that rough bluegrass has a floppy growth habit and is
not the most attractive lawn grass. But it will grow where no
other grass species will survive. Neither species will survive
long term in extremely dense shade or constantly saturated soil.
Once you have addressed the underlying causes that permitted the
moss to get the upper hand, then you can use a product
registered to eliminate moss. Scott's Moss Control, DeMoss from
Mycogen Corp. and LESCO Moss and Algae Eraser are chemical
controls registered in Pennsylvania to eliminate moss. Be sure
to read and follow label directions. If used improperly, both
products can "burn" desirable turfgrasses.
You might also consider taking the path of least resistance and
create a moss garden in your back yard. You obviously have ideal
conditions for moss to grow. You can purchase different types of
moss at garden centers and through mail-order catalogs. A
woodland garden planted with native wildflowers, mosses and
woody plants such as mountain laurel and rhododendrons may be
more appropriate for the conditions in your yard than turfgrass.
It is usually easier and cheaper to choose plants that fit your
site than it is to change the site to fit certain plants.
MORE
Lawn renovations
Sandy's gardening
columns
