August 31, 2019
Selecting the Right Turfgrass Variety for Your Yard
Reprint from 2009. Guest contributor Dr. Bernd Leinauer, NMSU Extension Turfgrass Specialist.
Question:
I want to plant a lawn with a grass that uses less water than ryegrass. Do you have any suggestions?
- B.L., Raton
Answer:
Dr. Bernd Leinauer, NMSU Extension Turfgrass Specialist, provided this information.
I am frequently asked about plant selection, but this can’t be answered without addressing two other areas: human expectations and irrigation system performance. I hope this will clear up some general misconceptions about turf water use.
A plant's water requirement is a very important aspect of plant selection here in the arid Southwest. In summer, outdoor watering accounts for 50% or more of urban domestic water use. Turfgrasses, which can make up a large portion of our landscapes, are consequently identified as "water guzzlers." One might think that removing traditional grasses (like Kentucky bluegrass, perennial ryegrass, or tall fescue) and replacing them with "low water use" grasses (buffalograss, blue grama, bermudagrass) would conserve large amounts of potable water. However, other factors must be considered.
New Mexico’s climate—dry, hot summers and cold, often dry winters—can be very challenging for plant selection. Generally, it is easier in our climate to maintain cold-tolerant plants in the summer than drought-tolerant, cold-sensitive plants in the winter. Therefore, cold tolerance is usually the first characteristic considered when selecting perennial plants—from turfgrasses to shrubs and trees. In addition to cold tolerance, turfgrasses often have to survive and recover from all sorts of abuse from sports like football and soccer, and regular traffic from children and pets. No wonder Kentucky bluegrass, perennial ryegrass, and tall fescue are considered desirable grasses for our lawns since they are the only ones that are both traffic-tolerant and aesthetically pleasing most of the year. This brings us to our next question: Which cold- and traffic-tolerant grasses use less water?
When selecting plants for water conservation, it’s important to decide what your quality and functionality expectations are. Do you want a green, playable surface that withstands traffic almost all year, or simply a landscape with ground cover where color or lack thereof is not important? If traffic tolerance is not important, we can use other cold-tolerant grasses with lower irrigation requirements than cold-season grasses like Kentucky bluegrass. Buffalograss and blue grama are native grasses with cold tolerances that make them suitable throughout New Mexico. These grasses will withstand mowing heights over 4 inches or can be left unmowed as ornamental grasses. Unfortunately, they can only be used in areas that receive little or no traffic, where the main purpose is landscape aesthetics. Furthermore, buffalograss and blue grama are warm-season grasses that go dormant (lose green color) during mid to late fall and stay colorless (grayish to tan-colored) until late spring or early summer. Areas planted with buffalograss or blue grama require little or no irrigation during dormancy. Buffalograss lawns look different from a traditional Kentucky bluegrass or fescue turf since the plants' canopy is more open and less dense and uniform, with more of a "meadow" appearance than a traditional lawn.
You may have noticed that I avoid the term “water use” and instead use the term “irrigation requirement.” It’s our observation, particularly in residential areas, that turfgrass areas are being irrigated well above what is required because of a lack of knowledge of how much water is needed. The blame is put on grasses that are labeled "high water users" when in reality these grasses do just fine with less water. Instead of how much water turfgrasses use, we should ask how little water they need to survive and meet our quality expectations. All turfgrasses, including Kentucky bluegrasses and tall fescue, can survive with less irrigation water using mechanisms that allow plants to adapt to drought. Turfgrasses can also survive longer periods without any irrigation, even in summer. Grasses simply go dormant and lose color (just like in the winter), but will turn green again after the water has been turned on. We have buffalograss test plots at NMSU in Las Cruces that have not been irrigated for 2 years, but green up for a brief period after every significant rainfall. The plots show green color only for a total of 4–6 weeks per year. This may not be acceptable for people who enjoy the green appearance throughout the summer, but it shows how resilient some grasses are. Even Kentucky bluegrass will go dormant and lose color in the summer when exposed to drought, but will recover when rain or irrigation resumes.
If sprinklers are used to irrigate, a catch can audit will tell us how much and how uniformly water is applied. A survey of irrigation audits throughout the Southwest showed that the average residential irrigation system has a distribution uniformity of 50%, regardless of sprinkler head type. To irrigate all areas of a lawn adequately with a system with 50% uniformity, the amount of irrigation water doubles compared to what "the grass needs" to maintain adequate quality. A poorly functioning irrigation system may therefore contribute more to wasted water than the grass species selected.
So, before you drastically change your landscape by either completely removing the turf or changing to a different kind of grass, consider the following: 1) What are your quality expectations? 2) If you use a sprinkler system, conduct an irrigation audit and learn how much water is applied with every irrigation. 3) If you feel you are wasting water by irrigating your lawn, start watering less. You will reach a point when the turf quality declines somewhat, but this slight decline in appearance may be acceptable and may result in significant water savings. 4) Consider alternative irrigation systems (such as subsurface drip) that apply water more uniformly and efficiently than traditional sprinkler systems. 5) Use warm-season grasses such as zoysiagrass, bermudagrass, buffalograss, and blue grama if you feel a change in species will not affect the purpose and functionality of your lawn.
Dr. Leinauer added, “After several years of research at NMSU, we conclude that Kentucky bluegrass is more drought tolerant than all other cool-season grasses and is highly recommended for turf areas if a cool-season grass is chosen.” Find more information on lawn care in NMSU Extension Publications.
This year, the Southwest Turfgrass Association will hold its annual conference in Albuquerque, October 15–17, 2019. Speakers from NMSU and other universities will present on topics and latest research findings on the sustainability of urban landscapes in the Southwest.
For Further Reading:
Guide H-508: Turfgrasses for New Mexico
Circular 660: Turfgrass Irrigation
Guide H-507: Lawn Care for Disease Control
Guide H-510: How to Perform a Catch Can Irrigation Audit on a Home Lawn Sprinkler System
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.
Links:
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.
Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!