Water Wise Landscape Design:
Selecting Turf for Water Wise Landscapes

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For additional information on turf selection, refer to Dr. Tony Koski’s website at http://csuturf.colostate.edu  and the following CMG GardenNotes:



Water-wise landscaping is not anti-turf, but rather about matching turf selection to the design needs and use of the site.  This is a change from the typical western landscape with high input lawn covering most of the ground. 

With Colorado’s population growth, water use becomes a critical issue. Water conservation helps 1) reduce total water demand, and 2) reduce the extensive cost of expanding a community’s water infrastructure.

In a typical community, water use more than doubles during the summer irrigation season.  On a statewide perspective, landscape irrigation accounts for 7 to10% of Colorado’s total water use.  Due to planning by forefathers, some communities have a good water supply supporting landscape irrigation.  However, during drought years water may be in short supply.  Other communities lack water resources for landscape irrigation.  Here limited irrigation or non-irrigation may be the only practical approach.  In Colorado, landscape irrigation is prohibited from newer domestic wells.

Benefits of Grass

Healthy grass is an aesthetic asset and a factor in property value.  It provides a backdrop for other landscape elements pulling the landscape design together.

The growing body of evidence points to the positive health and environmental contributions made by lawns and other grassy areas.  A healthy, vigorous lawn with high plant density provides the following benefits:

  • Conversion of carbon dioxide into oxygen – Twenty-five square feet of actively growing grass produces enough oxygen for one person per day.

    On a global basis, grasslands of the northern hemisphere are second to the tropical rain forests in the carbon dioxide to oxygen conversion.  Grasslands serve a major role in reducing global warming.

  • Pollution breakdown – Microorganisms found in the soil of actively growing turf breakdown organic pollutants, including air contaminates, pollen, and pesticides.

  • Wind erosion – Grass cover prevents wind erosion of soil, trapping dust and pollen.

  • Water quality – Turfgrass areas play a significant role in reducing surface water runoff, a key factor in non-point-source pollution in the landscape setting. 

  • An average golf course of 150 acres can absorb 12 million gallons of water during a three-inch rainfall.
  • A thick turfgrass allows 15 times less runoff than does a lower quality lawn.
  • A healthy, dense stand of turfgrass can reduce runoff to almost zero.
  • Compared to a garden or field planted to row crops, grassy areas reduce soil erosion by 84 to 668 times.
  • To protect surface water quality, direct surface runoff onto grassy areas allowing for natural filtering in the biologically active turf soil.

  • Soil structure – Actively growing grass supports soil organism activity that improves soil structure.

  • People space – Turf is basic “people space” with a cool, dirt-free activity space for children and adults.

  • Element of landscape design – Turf brings unity to a landscape design and provides a neutral background to set off flowers and shrubs.

  • Property values – Turf quality influences property appeal and marketability.

  • Fire defense zone – Irrigated mowed lawns is an important aspect of fire management in communities.  Dry, unmowed grass/weeds become a major fire hazard.

Turf Selection: Creating Practical Turf Areas

High input lawns are a habit in American and European landscapes since the days of King Louis of France.  However, does the property use require the perfect green lawn with high inputs or would a moderate quality lawn with reduced inputs or a low input lawn be acceptable for the site? 

Many lawn care problems arise from management differences between high, moderate and low input lawns.  For many gardeners, there is a conflict between expectations and inputs.  Table 1 summarizes difference in high, moderate and low input lawns.

Table 1.
Comparison of High, Moderate, and Low Input Lawns

 

High Input

Moderate Input

Low Input

Wear tolerance

best

good

limited

Appearance

best

good

limited

Water

high

moderate

limited

Exposure

sun

sun to partial shade

sun

Fertilization

spring and fall

primarily fall

fall


Species

  • Select KBG cultivars
  • Perennial rye
  • Turf-type tall fescue
  • Select KBG cultivars
  • Turf-type tall fescue
  • Buffalo grass
  • Select KBG cultivars
  • Blue grama
  • Buffalo grass


Grass and Water Use

Contrary to popular belief, there is no magic lawn type that delivers top quality with minimal inputs.  The quality of any turf is directly dependent on the amount of summer rainfall and supplemental irrigation it receives.

A lawn’s tolerance or resistance to drought is a complex situation.  A “drought tolerant” specie may or may not use and/or require less water depending on many factors.  Factors contributing to drought tolerance include:

  • Species (including its actual  water use, rooting depth, and ability to go dormant)
  • Soil tilth and soil oxygen levels (rooting depth)
  • Wind and sun exposure (actual water use)
  • Mowing height (high mowing leads to deeper roots).
  • Traffic, (any lawn is intolerant of traffic when dry).
  • Salt levels in soil and irrigation water.
  • Previous irrigation pattern (frequency and watering depth).

The bottom line is that species selection is secondary to irrigation management in water savings.  A more drought tolerant lawn species will not use less water if managed like a high input lawn!

Since Kentucky bluegrass, turf-type tall fescue, and Buffalograss make up 99% of home lawns in Colorado, this CMG GardenNotes only looks at these options.  For additional information on turf species, refer to CMG GardenNotes #561, Turfgrass Species Selection Guide.

If A Turf Is Deeper Rooting

If a turf is deeper rooting:

  • It requires less frequent irrigation (i.e., stays greener longer between irrigations).
  • However, it will also require a heavier/deeper irrigation to recharge the rooting zone, so actual water use is not necessarily reduced.
  • Deeper rooting may or may not be an irrigation savings technique depending on the frequency of soaking summer rains and the irrigation pattern.  If the area can depend on frequent summer soaking rains, the deeper rooting cultivars can be an advantage to keep the grass green between rain events.  If the lawn is automatically watered two or three times a week, rooting depth is a mute issue. [Figure 1]
  • Many gardeners mistakenly assume that deep rooting is a water savings because irrigation is needed less often.  However, the frequency of irrigation is not the primary factor to consider.  The issue is total water consumption.

Lawn rooting depth
Figure 1. Deeper rooting means less frequent irrigations, but heavier irrigations to replenish the rooting zone. It should not be interpreted as a water savings.


Kentucky Bluegrass Makes A Great Lower-Input Turf Option.

  • Kentucky bluegrass, KBG, is the standard for home lawns due to the rich blue-green color and its high tolerance for wear. [Figure 2]
  • Water use primarily depends on the gardener’s irrigation management.  On a community wide basis, we use twice the amount of water that the KGB lawns actually need.
  • Water use and growth actually slows when the soil begins to dry down.  However, to capitalize on this dry down requires careful irrigation management rather than automatic irrigation on fixed days of the week.
  • Irrigation demand varies significantly between cultivars.  Some deeper rooting cultivars require less frequent irrigations.   Some cultivars demand 25% less total water.
  • KBG goes dormant with water stress.  Summer dormant KBG is a standard in many parts of the eastern United States.  Just not in the arid west!  Will summer dormant with green lawns in the spring and fall work for the site?
  • Bottom line: It is not the KBG that demands the heavy irrigation but rather the gardener’s management style.

  • High input KBG makes a great “people space” for high use areas like a ball field with lots wear and tear.  Few home lawns have this high traffic situation demanding high inputs.
  • Moderate input KBG (irrigated at 80% ET) fits the need for most home lawns where a beautiful green lawn is desired.
  • When irrigated at 60% ET, KBG makes a thinner carpet.  This may be well suited for lower use areas.
  • Where summer dormant is acceptable, KBG makes a great minimal input lawn.  It needs to be greened up in the cooler weather of spring and fall with rainfall and supplemental irrigation. 
  • The primary public objection to summer dormant lawns is that so many are found in unkept yards that become the neighborhood weed patch.

Note: the term “ET” stands for evapotranspiration which is an actual measurement of the water use of the lawn (or crop) based on crop growth, temperature, wind, humidity, and solar radiation. 

Summer dormant Kentucky Bluegrass
Figure 2. Weed free, summer dormant KBG. The primary public objection to summer dormant KBG is that so many are simply no maintenance yards becoming the neighborhood weed patch.


Turf-Type Tall Fescue Makes A Great Lower Input Turf Option.

  • Turf type tall fescue may be deeper rooted than KGB, depending on soil tilth (oxygen levels), cultivars, and irrigation pattern.  This means it may go longer between irrigation, but should not be mistaken as water savings.
  • Tall fescue cannot slow growth and water use as the soil dries down.  Actual water use may be significantly higher than KBG. 
  • Tall fescue cannot go dormant.  In summer dry spells, it requires irrigation.
  • Based on ET, actual water use of turf-quality tall fescue is only 10% less than turf-quality KBG.  Irrigation management plays a larger role in water use than species selection.  Switching from a KBG to a turf-type tall fescue lawn will not save water!  Water savings comes in the management of the irrigation.
  • Tall fescue makes a great reduced-input turfgrass for site where top quality turf is not essential for the landscape design.

Buffalograss Quality Is Dependent on the Amount of Summer Rain and Irrigation It Receives.

  • Being a warm season grass, Buffalograss will be dormant brown from early fall (first frost) to late spring in Colorado. [Figure 3]
  • To be green in the summer, water use for Buffalograss is about 1 inch of rain and irrigation per week.  To remain green in Colorado summers, Buffalograss generally requires irrigation to supplement natural rainfall.
  • Turf-quality Buffalograss requires 50% less rain and irrigation per season than KBG.  This reduction is due, in part, from being dormant in the spring and fall.

Summertime Buffalograss and irrigated tall fescue

Figure 3. Summer lawn appearance. Back: Buffalograss, Front: Irrigated turf-type tall fescue. [Photo by Tony Koski.]




Comparative Seasonal Water Requirement

Figure 4 illustrates the comparative season water requirement (including summer rainfall and irrigation) of lawn options.  The typical lawn receives twice the amount of irrigation required for high input KBG.  [Figure 4]

Comparative water requirement of common turf grasses
Figure 5. Comparative season water requirement (including summer rainfall and irrigation) for Kentucky Bluegrass, Tall Fescue and Buffalograss. The typical lawn receives twice the amount of irrigation required for high input KBG.



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Authors: David Whiting, Extension Consumer Horticulture Specialist, Department of Horticulture & LA, Colorado State University and Jeff de Jong, Horticulturist, Victoria, BC. Artwork by David Whiting.

  • CMG GardenNotes are available online at www.cmg.colostate.edu
  • Colorado Master Gardener/Colorado Gardener Certificate Training is made possible by a grant from the Colorado Garden Show, Inc.
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  • Colorado Master Gardener LogoNo endorsements of products mentioned is intended nor is criticism implied of products not mentioned.
  • Copyright. 2010-13. Colorado Master Gardener Program, Colorado State University Extension. All Rights Reserved. CMG GardenNotes may be reproduced without change or additions, for nonprofit educational use.

Revised November 2013

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