Quick
Facts...
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Proper watering can promote a deeply rooted, healthier
turf.
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Let grass species and health, soil conditions, and
weather conditions dictate irrigation practices, not the
number of days between waterings.
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Mow bluegrass, ryegrass, fescue and wheatgrass to a
height of 2 to 3 inches. Buffalo-grass and blue grama
lawns can be mowed to this height, but also do well
unmowed.
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Core cultivation is essential for all lawn areas,
especially those that are thatchy or subject to high
traffic.
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Before
planting a lawn, decide on the desired quality, how the lawn
will be used, and how much time and money you are willing to
invest. Have your soil tested. Contact your Colorado State
University Cooperative Extension county office for
information on soil testing. Soil amendments can easily be
added before planting. High quality sod or seed also helps
ensure a satisfactory lawn.
Watering
Many
factors influence lawn water requirements, and no two lawns
are exactly alike. A healthy, high-quality bluegrass or
ryegrass lawn may need up to 2.25 inches of water per week
under hot, dry, windy summer conditions. It may require much
less when the weather is cool or cloudy. Turf-type tall
fescue may perform well with less water than a bluegrass
lawn, if it can grow a deep root system. In many cases,
however, tall fescue requires as much water as bluegrass to
look good. Buffalograss and blue grama lawns can remain
green for weeks without watering, even during the hottest
summer weather.
Shady
lawns and areas protected from the wind require less water
over the growing season than more exposed turf. However, the
roots of mature trees and shrubs also need water. You may
have to water more in mature landscapes where the roots of
many plants compete for water. Healthy turf, encouraged by
proper mowing, fertilizing and cultivation, uses water more
efficiently.
Application
Each
time you water the lawn, apply enough water to moisten as
much of the root zone as possible. Use a soil probe or
shovel to determine what the average rooting depth is in
your lawn. If the roots grow down 6 inches deep, water so
the soil is moistened to that depth.
If the
soil is mainly clay, apply 1 to 1 1/2 inches of water to
moisten the root zone to a 6-inch depth. A sandy soil can be
moistened to 6 inches by as little as 1/2 inch. It is
important to know not only how deep the turf roots grow, but
also how deep your irrigation water penetrates. Watering too
deeply, especially on sandy soils, wastes water and allows
it to percolate past the root zone.
Frequency
Based
on the above, grass that grows on sandy soil must be watered
more often than the same grass growing on clay or loam
soils. Even after a thorough watering, sandy soils hold
little plant-available moisture. They require more frequent
irrigation with smaller amounts of water. Conversely, turf
growing on a loamy-clay soil can be irrigated less
frequently, with larger quantities of water. Watering less
often means more efficient water use because of less loss to
evaporation. It can also reduce the number of weeds that
appear in the lawn.
With
most soils, do not apply all the water in a short period of
time. If applied too quickly, water often runs off of
thatchy turf, from sloped areas, or from turf growing on
heavy clay or compacted soils. In these cases, it is more
effective to apply only a portion of the water and move the
sprinkler or switch to another station to water another
section of the lawn. This allows water to soak into the soil
rather than run off. An hour or so later, apply the rest of
the water. Core cultivation (aeration) can resolve some
infiltration problems by reducing thatch and compaction.
Wetting agents may enhance water movement into the soil, but
they should not be considered a cure-all, especially when
compaction or thatch are problems.
A sure
sign that turf requires irrigation is a wilted appearance.
One symptom is "footprinting," footprints on the lawn that
do not disappear within an hour. This symptom is soon
followed by actual wilting, where the turf takes on a
grayish or purple-to-blue cast. If only a few such spots
regularly appear in the same general location, spot water
them to delay watering the entire lawn for another day or
so. These indicator spots help predict when the entire lawn
needs watering. A hardened or toughened lawn, attained
through less frequent, deep irrigation, often withstands
minor drought and generally has fewer disease problems. It
is important, however, that the turf not be allowed to
become overly drought-stressed between waterings. This
weakens the turf and makes it more susceptible to insect and
disease damage and to weed invasion.
During
extended dry periods from late fall to spring, it may be
necessary to water every four to six weeks if the ground is
thawed and will accept water. Pay particular attention to
exposed slopes, sites with shallow soil, and south- or
west-facing exposures.
Time
of Day
The
most efficient time of day to water is late evening and
early morning (between 10 p.m. and midnight or 8 and 9
a.m.). It generally is less windy, cooler and more humid at
this time, resulting in less evaporation and more efficient
use of water. Water pressure is generally better and this
results in optimal distribution patterns. Contrary to
popular belief, watering at night does not encourage disease
development.
Check
with your local water department before you water at night.
Some city ordinances prohibit irrigation during these hours
to avoid the waste that occurs when sprinklers are left
running in the same place all night.
Mowing
The
two most important facets of mowing are mowing height and
frequency. The minimum height for any lawn is 2 inches. The
preferred mowing height for all Colorado species is 2.5 to 3
inches. Mowing to less than 2 inches can result in decreased
drought and heat tolerance and higher incidence of insects,
diseases and weeds. Mow the lawn at the same height all
year. There is no reason to mow the turf shorter in late
fall.
Mow
the turf often enough so no more than 1/3 of the grass
height is removed at any single mowing. If your mowing
height is 2 inches, mow the grass when it is 3 inches tall.
You may have to mow a bluegrass or fescue lawn every three
to four days during the spring when it is actively growing
but only once every seven to 10 days when growth is slowed
by heat, drought or cold. Buffalograss lawns may require
mowing once every 10 to 20 days, depending on how much they
are watered.
If
weather or another factor prevents mowing at the proper
time, raise the height of the mower temporarily to avoid
cutting too much at one time. Cut the grass again a few days
later at the normal mowing height.
Let
grass clippings to fall back onto the lawn, unless they are
used for composting or mulching elsewhere in the landscape.
Grass clippings decompose quickly and provide a source of
recycled nutrients and organic matter for the lawn. Mulching
mowers can do this easily. Side-discharge rotary mowers also
distribute clippings effectively if the lawn is mowed at the
proper frequency.
Grass
clippings do not contribute to thatch accumulation. If
herbicides are applied to the lawn, do not use clippings in
the vegetable or flower Gardens. Keep them on the lawn.
During
the season, regularly check mowing equipment for sharpness
and adjustment.
Sharpen rotary mower blades every fourth mowing, especially
when mowing fescue or ryegrass lawns. A dull mower blade
will shred and fray leaf blades instead of cutting them
cleanly. The result is a brown, unattractive lawn.
Check
reel-type mowers for proper blade-to-bedknife adjustment
before each mowing to avoid shredding and tearing of the
grass leaves.
Thatch
Thatch
is a tight, brown, spongy, organic layer of both living and
dead grass roots and stems that accumulates above the soil
surface. The interactions among environmental conditions,
soil conditions and management practices (irrigation,
mowing, fertilization) influence the rate and extent of
thatch accumulation. Thatch tends to be a problem on
Kentucky bluegrass, bentgrass and fine fescue lawns. It is
rarely a problem with tall fescue, wheatgrass, bromegrass or
buffalograss. Grass clippings do not contribute to thatch
accumulation and should be returned to the lawn during
mowing to recycle the nutrients they contain.
Measure thatch buildup by removing a small piece of turf,
including the underlying soil. Try to slow buildup when the
thatch layer exceeds 1/2 inch in thickness. The thickness
can increase quickly beyond this point, making it difficult
to control later. As the thatch layer thickens, it becomes
the main rooting medium for the grass. This predisposes the
turf to drought stress or winter kill and increases the
possibility for insect, disease and weed problems. Also,
fertilizers and pesticides applied to a thatchy lawn work
less effectively.
Power
Raking
This
method of thatch removal has been used for years. Light
(shallow) power raking may be beneficial if done often. Deep
power raking of a thatchy lawn can be damaging, and often
removes a substantial portion of the living turf. Used
properly, power raking of wet, matted turf can speed spring
green-up by letting air move into the root zone and warm the
turf.
Compost the thatch and organic material to kill any living
grass before it's used as a mulch or soil amendment.
Core
Cultivation or Aerating
This
is more beneficial than power raking. It helps improve the
root zone by relieving soil compaction while controlling
thatch accumulation. Soil compaction, in fact, is one factor
that contributes to thatch buildup.
Aeration removes plugs of thatch and soil 2 to 3 inches long
(the longer, the better) and deposits them on the lawn. A
single aeration using a machine with 1/2-inch diameter tines
removes about 10 percent of the thatch if enough passes are
made to achieve an average 2-inch spacing between holes.
Disposing of the cores is a matter of personal choice. From
a cultural perspective, there may be an advantage to
allowing the cores to disintegrate and filter back down into
the lawn. Mingling soil and thatch may hasten the natural
decomposition of the thatch. The little fluffs of thatch and
turf that remain can be collected and composted.
Depending on soil type, core disintegration may take a few
days to several weeks. Irrigation helps wash the soil from
the cores. Dragging a piece of cyclone fence or an old metal
door mat can speed the process. Running over the cores with
a rotary mower can be effective but can dull the blade. Many
commercial companies that perform core cultivation break up
the cores with a power rake. If the cores are removed from
the lawn, compost them before using them as a mulch or soil
amendment.
Fertilization
Nitrogen is the most important nutrient for promoting good
turf color and growth. Do not overstimulate the turf with
excess N, especially during the spring and summer. Table 1
suggests nitrogen application programs for various lawn
species. To obtain a high-quality, water-resistant turf with
greater pest resistance, follow the suggestions in the
table.
Overfertilization can contribute to thatch buildup and
increased mowing requirements. Avoid underfertilization of
bluegrass and ryegrass. These species can become unhealthy
if not fertilized properly. Turf that does not respond to
nitrogen fertilizer may be lacking in other nutrients, such
as phosphorus or iron. Get the soil tested to determine
which nutrient(s) are deficient.
Balanced or complete fertilizers contain various amounts of
phosphorus, potassium, iron and sulfur. They are a good
safeguard against a potential nutrient deficiency. If you
leave clippings on the lawn, these nutrients are recycled
from the clippings. If you remove clippings, this type of
fertilizer is appropriate. |
