Management Before, During, and Following Drought in Colorado
By Laura Pottorff and David
Whiting, Colorado State University Cooperative Extension, Horticulture
Precipitation, snow pack, stream flow, and
reservoir levels are significantly lower than historic averages throughout Colorado and
the Rocky Mountain region. During normal precipitation years, landscape irrigation
comprises 50% or more of urban water use during the growing season in the Rocky Mountain
region. In anticipation of restrictions in irrigation that may be imposed by water
utilities, communities, and other water-management entities, suggested irrigation
management practices are offered.
The following practices allow you to have a green
lawn, healthy landscape and still reduce water consumption
Improve Irrigation Efficiency
Replace broken or missing sprinkler heads and straighten
Check that rotor heads are turning properly.
Adjust heads so that water is not thrown onto streets and
Check nozzles for plugging and clean filters.
Place containers on persistent dry spots to determine if
poor sprinkler coverage is the problem.
Regulate the pressure at individual zone valves to spray
droplets instead of a mist that drifts and evaporates, wasting water.
- Never water if the soil is still
Water to meet the needs of plants. Review how to set
irrigation days, zone start times and run times so adjustments can be made for the season
and weather. Newer irrigation controllers allow dialing down water applications to a lower
percentage and increasing them during peak summer heat to close to 100 per cent.
Water as infrequently as possible, without causing undue
stress to the lawn and other landscape plants.
Turn the irrigation controller to the "Manual"
position (from "Automatic") and learn how to operate it manually.
Dont irrigate on a set schedule (every 2 or 3
days); plant water use can vary greatly from one day to the next.
Lawns may need water every three or four days during the
heat of the summer, less in cooler times of year. Shrubs and trees may need water only
once every few weeks, while perennial flowerbeds may need water only once a week. Plants
growing in sandy soils may need more frequent watering.
The roots of trees, shrubs, and flowers may rot if
watered on the same schedule as the lawn. Water-logged conditions do not favor the growth
of healthy plants. Over-watered plants with root damage need more water in the heat of the
Irrigate when footprints or mower wheel tracks become
easily visible on turf and large areas of the lawn take on a bluish-gray color.
Place straight-sided containers (such as soup or bean
cans, etc.) around the yard and measure output so that you know how long it takes to apply
¼ to ½ inch of water. Apply ¾ to 1 inch of water, slowly enough that runoff and
puddling does not occur. Cycle through irrigation stations or frequently move a sprinkler
around the yard to allow water to soak in more thoroughly and evenly.
Dont water again until abundant signs of water
stress (footprinting, blue/gray coloration) appear in the lawn.
Hand-watering small or isolated dry spots can allow
extending the time between watering by another day without watering the entire lawn.
Designing an irrigation system
- Sprinklers should be zoned properly so lawns can be watered separately
from trees, shrubs and flowers. Also water vegetable beds and rose gardens separately from
lawn areas. Place trees and shrubs in areas separate from lawns. Position woody plants on
higher ground if they are in the lawn area.
- Design sprinklers to "line out" driveways, walks, roads and
non-irrigated areas. Sprinklers should be next to hard surfaces to throw water onto
landscape areas. Avoid a design where the sprinkler heads shoot from the center towards
- Design irrigation zones so water from one head touches the neighboring
head(s). Too much space between sprinkler heads creates dry spots. Sprinklers are best
installed in a triangular or square pattern with water from
one head touching the neighboring two heads. Sprinkler heads that do not overlap cannot be
expected to properly water the intended area properly.
- Install only as many heads on an irrigation zone as the water pressure
will allow. Irrigation heads are calibrated to apply a certain amount of water over a
specific area at a set water pressure. Installing more heads than the water system will
handle results in dry spots. Symptoms of low water pressure often appear as donuts of
green grass around the sprinkler head with dry areas between heads.
- Avoid oscillating sprinklers and sprinkler heads that produce mists or
- Do not install different types of sprinkler heads in the same irrigation
- Rotary, spray heads and impact sprinkler heads put out different amounts
of water. Impact sprinklers heads may put out as little as ½ inch of water per hour,
while pop-up spray heads may apply up to two inches of water per hour.
- Install the same type of head with the same precipitation rate within
each zone. Otherwise water will be wasted.
- Long sloping turf areas may require several different sprinkler zones;
each line of sprinklers, controlled by a valve, is called a zone.
- Irrigation zones should be installed along the top of the slope, rather
than up and down the slope. The slope may require two or more lines of sprinklers, each
controlled by its own valve. Adjust sprinkler zones running along the middle and bottom of
the slope so they apply progressively less water than the sprinklers at the top of the
slope. Water runs down hill. Reduce the amount of water in each zone accordingly. Watering
for the same amount of time in each zone wastes water.
- If possible, install water-conserving devices such as check valves,
pressure regulators or climate sensors (i.e. rain, temperature and wind sensors). These
will suspend irrigation when unfavorable weather conditions exist.
Maintenance Practices for Managing the Changing Water Needs of
- Reset automatic controllers according to seasonal needs of plants.
Controls should be inspected at least once a month to adjust run times. This seasonal information is available in most communities from
the city or water supplier.
- Winter watering can be a critical tool to minimize stress to trees,
shrubs, flowers, and turf in areas receiving low winter precipitation and subject to
- Application of water once a month during dry winter periods will allow
plants to emerge from winter healthier, requiring less water in the spring. A commonly
seen situation is overwatering in spring in a vain attempt to help plants recover from
winter drought stress. Timely winter watering avoids this.
- Plants mature and change. Add or relocate system components as needed to
maintain uniform distribution of water. Ensure that system modifications do not exceed the
system watering capacity.
- Drip irrigation installed at the base of large transplanted trees should
be moved as the tree root system expands. Drip irrigation that is not relocated over time,
wastes water because the fine roots that pick up moisture have grown away from the base.
Tree roots spread outward, two to three times the width of the tree canopy. Drip
irrigation located at the base of the tree does not deliver water to roots five or more
feet away from it.
- As a landscape matures, more shade develops from trees. Plants growing in
shaded conditions often use less water.
Photos: Carl Wilson, Judy Sedbrook
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