Lawn irrigation accounts for nearly half of
homeowner water usage. Many homeowners
irrigate too often and for too short a period to
meet lawn and especially landscaping (tree
and shrub) needs. Others tend to leave the
water running too long, resulting in wasted
water.
Turf studies show that most lawns only
require irrigation once every 4 to 8 days to
stay healthy and green. Shallow rooted plants
result from irrigating every day.
Irrigating less often and applying more water
per irrigation results in deeper rooted plants
and a healthier turf. Grass roots grow deeper
into the soil and the plants become stronger if
enough water is applied when you do irrigate.
If grass doesn’t spring back after being
stepped on, it’s probably time to irrigate.
It takes less water to maintain a gre en lawn if
soil fertility is high. Weed levels also tend to
be lower in a well fertilized lawn.
For optimal results, apply your fertilizer in
split applications rathe r than one spring
application. For example, in the Snake River
Plains and Eastern Oregon and Washington,
apply 2 pounds of ammonium sulfate each
“holiday” during the growing season -
Memorial Day, July Fourth, Labor Day, and
Halloween.
Two fertilizer applications, while not as good
as four, is better then one spring application.
Split applications also reduce the danger of
burning your lawn or risk of surface runoff
and deep leaching from a high nitrogen
application.
Irrigate through mid-September. Allow plants
to slow their growth and harden for winter.
Water again about mid-October to store
moisture in the soil.
Evergreen shrubs and trees transpire during
the winter, so it’s important they have
adequate soil moisture to ensure they don’t
stress during the winter period. A deep
watering just prior to soil freeze up will help
ensure shrubs and trees are healthy the next
spring.
The irrigation schedule on the next page offers
a guide. Your lawn may need more water
when it is especially hot or less during cooler
periods or when it rains. Avoid irrigating if
possible on windy days and midday when the
evaporation level is the highest. Try to irrigate
during early morning hours to avoid fungal
diseases. Proper lawn irrigation can save a lot
of water – and it saves you money.