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Irrigation Introduction
Return to Landscape 101
Watering your
lawn and plants is the most important part of a successful
landscape maintenance program. Consistent watering during
the summer months is the key to a green lawn and healthy
plants. It doesn't make sense to invest money in plants,
flowers, and grass, and not take care of them. The following
guidelines provide a complete watering guide for north metro
Atlanta. The guidelines assume a typical red clay soil,
which is predominant in this area.
Portable hose
sprinklers are time consuming and inefficient. Nevertheless,
it beats not watering at all. The biggest problem here is
the best time for watering is the early morning. Watering in
the evening increases your chances for fungus, a real killer
of fescue grass. Holding a hose on each plant for 20
seconds will adequately water each plant. Trees, especially
larger trees, require more water.
Repetitive
annual droughts are slowly killing many trees.
Unfortunately, when you see your tree dying, it is generally
too late to save it. Do not neglect watering your trees, as
they may take many years to replace. Your yard and shrubs
can be replaced much more quickly.
The most efficient and consistent method of
watering your landscape is with an underground lawn
sprinkler system. A well designed system consistently
applies the right amount of water to every part of the yard
at the right time of day while you are spending your time
doing something more important. It saves you time by
efficiently watering your lawn automatically or with the
push of a button. It also saves you from running your
sprinklers too long, thus not wasting water.
Follow local
water restriction guidelines (see
when to water). To understand the basis for
watering guidelines, here is a little information about
water absorption into the soil. The prevailing soil type for
the north metro Atlanta area is Georgia red clay. Clay is
superfine particles with properties similar to glue and
cement. The clay binds together and compacts with virtually
no air pockets. Tilled and aerated clay quickly compacts
unless organic matter is added. Water does not absorb well
into clay, and plant root systems tend to be shallow. Since
water does not absorb, sunlight will dry the soil quickly.
Therefore, frequent watering, daily, or every other day, is
required. The frequency of watering is based on evaporation.
During sunny 90 degree days, it may be necessary to water
every day in sunny areas. When temperatures are 72 degrees
or below, water only as necessary.
Pay
attention! Look at the soil in your yard. If it is very dry,
then water. If your soil is wet and not drying out, water
less. Waterlogged soil that does not dry out will kill
plants and grass. Many books on landscaping advise watering
deeply, to a depth of 6 to 7 inches, then allowing plants to
dry out for several days. This method only works where
plants or grass are planted in soil with a lot of organic
matter added to a depth of at least 6 inches. We advise
using the automated watering feature on your controller only
during periods of consistent weather. At other times water
automatically as needed, or by using the manual start
feature on your controller when the landscape needs
watering. We recommend purchasing a rain gauge to measure
rainfall amounts. Rainfall amounts of 1/4 inch or less are
insignificant. The sprinkler system is generally only needed
from mid April through October.
Georgia's
Water Ban: The Georgia Department of Natural Resources (DNR)
has implemented the following water restrictions:
-
Odd numbered
addresses water on Tuesdays, Thursdays, and Sundays (no
hourly limits)
-
Even numbered or
unnumbered addresses water on Mondays, Wednesdays, and
Saturdays (no hourly limits)
Watering
early in the morning, from 5 to 8 A.M., is best.
Watering in the evening can cause fungus to infect your lawn
and plants. If your plants are very dry it is better to
water them at night than not at all, but practiced
consistently watering at night is sure to invite fungus,
especially on fescue lawns.
As a general
guideline, sprinkler zones comprised of rotor sprays, a
stream of water that moves back and forth, should water from
16 to 22 minutes. Sprinkler zones comprised of fixed sprays,
a fixed misting spray of water, should water from 6 to12
minutes. Hot sunny areas need longer durations than shady
areas. These are only general guidelines. It is your
responsibility to monitor the wetness of your yard. Common
sense should tell you, if your yard is too wet, decrease the
watering time, and if it is too dry, increase the time.
Let's say a
portion of your yard is watered by one zone. Part of this
yard is adequately watered, while another part receives too
much or too little water. The amount of water applied by the
sprinkler system can be adjusted by changing the nozzle on
your sprinkler head. The Hunter PGP rotor sprays have 12
different nozzles. The least amount of water is nozzle one,
which emits a fine stream of water. At the other extreme,
nozzle 12 emits a large amount of water and, if necessary,
can be sprayed a longer distance. The Hunter SRS fixed
sprays utilize either Hunter or Rainbird spray nozzles. The
Rainbird nozzles emit less water per minute, but are more
susceptible to clogging due to the smaller aperture, the
opening through which the water sprays. Hunter nozzles emit
more water and can shoot the water a little bit further if
needed. The variable arc nozzles can be closed altogether if
an area is too wet.
Watering
needs vary depending on sun and wind exposure and soil
drainage. Areas in shade and poorly drained soils, which
tend to stay wet longer, need less water. For example, a
shady area on the side of the house where the air
conditioner drains needs less water than the front side of
the driveway out in the full sun. Therefore, a watering zone
extending from the street along the side of the driveway and
along the house cannot adequately water the front by the
street without over watering along the side of the house.
Sometimes, it is best too split a zone into two separate
zones, one for the shady area and one for the sunny area.
However, this is an extra cost at the time of installation.
To keep the cost of your sprinkler system competitive, this
option is usually not quoted in the cost of a sprinkler
system.
If your
budget allows, the best sprinkler system waters the entire
yard. Also, shaded areas, or areas that tend to stay wet,
should be watered separately or not at all. At a minimum,
you should have your front yard watered. The front yard
maximizes your house's curb appeal and it's resale value.
Most front yards can be watered in two zones. Additional
zones to water the rest of your yard may be added later.
If you live
in Fulton or Cherokee County, you should consider purchasing
a separate water meter from the county to avoid sewer
charges. The payback period on this investment is two to
three years.
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