Prescription for a
healthy turf
Proper
watering, fertilization and mowing help maintain a verdant lawn
March 18, 2004
Loretta Johnson and
There are so many people questioning why their lawns look poor, weak, or
even have dead or dying spots. Turfgrass health is
dependent upon proper care that maximizes root growth. The health of your turf
rests on its ability to resist disease and handle stress. Root-healthy culture
requires proper watering, fertilization and mowing. Although turfgrasses can appear to thrive on improper care, they
will not sustain good year-round health and vigor.
Irrigation is one of the most basic practices, but is also the one most
often done incorrectly. Shallow frequent watering promotes shallow root growth.
Turfgrasses should be watered more deeply and less
frequently. Water to provide moisture equivalent to one inch
per week in hot dry weather - or moisture to a depth of six inches.
Repeat only as signs of drought stress appear. Early morning is the best time
to water. Late evening watering makes turfgrass more
susceptible to disease. Over-watering can lead to wet wilt, leaching and loss
of nutrients, and polluting runoff. Check your sprinkler or irrigation system
to avoid loss of water from wind shift and runoff.
Lighter grass color is not necessarily an indication of poor plant health,
but rather an indication of the lack of essential elements. Light color is
usually a sign of a shortage of nitrogen, but can also result from a shortage
of micro-nutrients such as iron and zinc caused by an overabundance of
phosphorus. Establish a fertilizing program, and don't let grass color
influence your fertilizer applications.
Begin your fertilizing program by soil testing, which can be obtained
through Texas Cooperative Extension. Contact the
The three major nutrients required by grasses are nitrogen, phosphorus and
potassium, listed in order on bags of fertilizer. An example would be 21-7-14.
This would be known as a 3-1-2 NPK ratio, N for nitrogen, P for phosphorus and
K for potassium. In this case it would contain 21 percent nitrogen, 7 percent
phosphorus and 14% potassium by weight. A 40 lb. bag then would contain 8.4 lb.
of nitrogen, 2.8 lb. of phosphorus and 5.6 lb. of potassium. The label will
also quantify the relative amounts of readily available (soluble) nitrogen and
slow release nitrogen.
Some fertilizers are advertised as slow release. A fertilizer with 50
percent slow release is most desirable. If this is unavailable, you might
consider using the lower nitrogen organic fertilizers. These are easier to
apply because higher spreader feed rates can be used. Organic fertilizers are
slow release and not as susceptible to nitrogen leaching and runoff. These are
particularly good for sloping lawn areas.
For home lawns, the Texas Cooperative Extension recommends application of no
more than 1 pound of soluble nitrogen per 1000 square feet of lawn at 8-10 week
intervals, if needed - that means if your grass is showing deficiency symptoms.
That is only three times per year - if needed. One or two applications may even
be enough for some yards. More frequent fertilizing is not needed. The first
fertilization should not start until around mid-April. This assures active
growth for warm season grasses and allows for some die-off of winter weeds
before fertilizing. Final application can be made between mid-September
up to mid-October. However, applications should be reduced to one-half rate of
normal or 1/2 lb. of nitrogen per 1000 square feet of lawn after September 1st.
Over-fertilizing after September can just promote brown patch disease.
To illustrate that the application rate of 1 pound of readily available
nitrogen per 1000 square feet of lawn is a light application of fertilizer,
let's look at an example of actual lawn area in an 85' X 170' lot, 14, 450
square feet or approximately 1/3 acre. Subtract from that the square feet of
non-lawn areas to determine square feet of lawn: House - 1980 square feet,
garage - 538, patio - 420, driveway - 720, sidewalks - 364, and landscaping
beds - 425. So the total lawn area is 10,013 square feet.
Let's use that same 40 lb. bag of 21-7-14, 50 % slow release fertilizer.
10,013 square feet divided by 1000 square feet is approximately 10, so we would
apply 10 X 1 lb. of nitrogen or 10 lb. We found that the bag contains 8.4 lb.
of nitrogen, so we would need to apply 1.2 bags on the entire lawn area! It's
better to put on less than more, so in this case one bag would be sufficient.
More is not better. Fertilizing at an arbitrary rate per 1,000 square feet
or so many times per year is strongly discouraged for a number of reasons. You
are likely over-fertilizing. It potentially increases leaching and runoff, a
major source of pollution in our streams and rivers. Over fertilization wastes
your money and time and requires more frequent mowing and watering. Also,
excess nitrogen will be converted to leaf growth at the expense of root
structure growth, resulting in less resistance to drought stress, insects and
disease. It promotes increased thatch buildup, promotes fungal diseases such as
Brown Patch and Take-All Patch, and will increase already high non-reversible
levels of phosphorus which can lead to plant deficiencies of iron and zinc. To
further emphasize this point, a recent soil testing campaign promoted by the
Victoria County Master Gardeners indicated 75 percent of the
Mower height for
Do not bag grass clippings. Allow the cuttings to return to the lawn. They
provide natural fertilizer with a NPK ratio of 3-1-2, just like your
fertilizer. Clippings will not increase thatch buildup if proper mowing
frequency is maintained, but can lead to too high nutrient levels and even
possibly disease problems if you indiscriminately over-fertilize.
Good lawn care practices will minimize the risk of significant damage from
disease and insects which are increased in stressed lawns. Grubs, chinch bugs,
weeds, brown patch and take-all patch are pests that can be a problem in the
So there you have it. This is the third and final article on turfgrasses for this spring. The articles were intended to
provide a factual overview for growing turfgrass in