1 Irrigation Cycles Per Week Recommended
(4/3/2013) Unless it Rains......
(1 irrigation cycle recommended per week, during the
Spring and late Fall)
(2 Irrigation Cycles recommended per week, during the
(3 Irrigation Cycles recommended per week, Mid - Late
Summer or when drought conditions exist or if
on a hillside or sloap)
Check the index once a week, on the first of your assigned watering
days. The "weekly watering amount" shown is the amount needed over the
next 7 days to replenish your lawn. If you're watering only once
weekly, apply the entire amount to your lawn. If you prefer to water
twice a week, apply half the watering amount on your first scheduled
watering day, and the remainder on your second day.
What do all these numbers mean?
These numbers show various weather data that help determine how
much water your lawn really needs. High and low temperatures (shown)
are just two of the factors used to calculate the potential
evapotranspiration amount, shown here as "ETo." You can think of ETo
as the amount of water a plant would need if left constantly exposed
to the sun, above the ground. Since most plants are actually in soil
and have varying amounts of sunlight throughout the day, we apply
stress coeffients for an average St. Augustine lawn in Austin to
determine the ET Index.
What is evapotranspiration?
Evapotranspiration is a measurement of the total amount of water
needed to grow plants and crops. This term comes from the words
evaporation (i.e., evaporation of water from the soil) and
transpiration (i.e., transpiration of water by plants). The equation
used to determine potential ET (ETo) considers a large number of
weather factors, including wind, temperature, dew point, humidity and
If we know how much water is lost each day, why don't we water
Allowing your lawn to dry out between waterings actually encourages
a deeper root structure -- the grass has to look deeper in the soil
for the water it needs. Plants with deeper roots are better able to
withstand drought, harder to uproot, and can be more resistant to
disease. Plus, the daily ET amounts for Austin are usually very small.
Most automatic irrigation systems cannot be adjusted to water less
than 1/4" with each operation, so it would be next to impossible to
apply only a tenth of an inch daily.
How do I know when I've watered enough?
Set empty tuna or cat food cans at intervals around your lawn and
garden. Turn on your sprinkler for 15 minutes. Measure the amount of
water in the cans. Now that you know how much water your sprinkler
puts out, you can figure out how long to leave it running when it's
time to water.
Example: After 15 minutes of running your sprinkler, you have an
average of 1/4" in your tuna cans. When the ET Index is 1/2" (and you
haven't had any rain), you should run your sprinkler for 30 minutes.
For an ET of 1/3", you'd run the sprinkler for about 20 minutes.
Disclaimer: Never make
important decisions of any kind, based off of information received
from the internet. (this includes when and how much to water your
lawn) Real Green is not responsible for any damages from the
use of any information, received from this website.