Throughout Texas, drought conditions and water restrictions have been impacting our landscape choices. A growing number of cities, for example, either recommend or have passed ordinances requiring drought-tolerant grasses for new residential and commercial development.
So, what is drought-tolerant grass? Basically, it’s an already-established grass that has the ability to withstand the stresses of prolonged dry spells on a regular basis, without sustaining lasting damage. Various grass types achieve this in a number of ways.
Turgidity
One method is by maintaining turgidity (water pressure in a plant’s cells). Grass irrigated regularly has a high turgidity and remains upright.
Drought-tolerant grasses attempt to keep their turgidity when water content is low by reducing cell size and closing up leaf pores to prevent the release of water (transpiration). Slowing down the release of water also slows down the grass plant’s ability to make its own food (photosynthesis). As the soil dries out, the grass gradually loses turgidity and wilts. Basically, the plant enters survival mode by no longer putting water and energy into active growth.
Deeper Roots
Another method is to grow deeper roots. Fully established grass plants are able to grow a deep, extensive web of roots that can access water far beneath the surface, allowing them to tolerate a drought longer.
This is why it’s important to irrigate once a week for long enough that the water penetrates the soil to a greater depth. Then, when the grass becomes water-stressed, it will send its roots further down towards the moisture. Daily irrigation for less than an hour will only create shallow surface roots.
Dormancy
Drought-tolerant grasses have a better ability to go dormant and turn brown in response to extended drought conditions. This is a method of protecting themselves and focusing on keeping their roots alive. When water becomes available, they can regenerate from crowns, stolons or rhizomes. The length of dormancy depends on the overall health of the grass plants, and the genetics of the species.
Two Categories of Drought-Tolerant Grasses
Drought-tolerant grasses fall into two categories: warm-season and cool-season.
Warm-season grasses prefer temperatures between 80°F and 95°F and are found mainly in the southern United States where the summers are hot and the winters are milder. They only need a fraction of the water required by cool-season grasses and are well-suited to areas with water restrictions. When the temperature drops below 55 °F, warm-season grasses start to turn a tan color. At the first frost, they turn brown, and go dormant during the winter.
The best warm-season drought-tolerant grasses in south Texas include Bermuda, buffalo, St. Augustine, and zoysia.
Cool-season grasses grow best in the spring and fall, between temperatures of 60°F and 75°F and are found mainly in north Texas. They don’t do well in most areas of the state because of the summer heat and high humidity.
The best choices for cool-season grasses that can survive during a drought in north Texas include Kentucky bluegrass, ryegrass, tall fescue, and Texas bluegrass.
Drought-Tolerant Warm-Season Grasses
Bermuda
Characteristics
- Fine to medium leaf texture with dense, dark green blades
- Root system can extend down to six feet
- Many varieties available in seed, while others established only by sod, sprig (thin 3- to 6-inch pieces of grass stems or runners (stolens) without soil), or plugs (2- to 4-inch chunks of sod, either round or square, with soil around their roots)
- Requires full sunlight
- Used on residential and commercial landscapes, sports fields, golf courses, parks and recreation areas
- Goes dormant in the winter, and turns tan to brown below 55°F
- Often overseeded with ryegrass in winter to maintain green color
- Texturf and Celebration are among the most drought-tolerant varieties
Strengths
- Establishes quickly, spreading by both horizontal above-ground shoots called stolons, and underground rhizomes
- Stolons and rhizomes can fill in bare spots
- Excellent heat tolerance up to 110°F
- High tolerance to foot traffic, and recovers more rapidly than other grasses when injured
- Low disease potential
- Low water user, needing 1 to 1.25 inches of water weekly from irrigation or rainfall to stay green
- Goes dormant in an extended drought after 50 days, and can survive up to three or four weeks without dying
- Responds quickly to watering after drought
Weaknesses
- Low shade tolerance
- Requires frequent mowing
- Moderate to high fertilization requirements
Buffalo
Characteristics
- Fine-textured, curly-leafed grass with colors ranging from dark-blue green to bright green
- Root system can extend down to six feet
- Varieties available in sod, seed, and plugs
- Does best in full sunlight
- Used in residential landscapes, parks, golf courses, highway and roadsides
- Goes dormant and turns brown in the winter
- Prairie, Prestige, Density, and 609 are among the best varieties for Texas
Strengths
- Establishes quickly, spreading by stolons
- Excellent heat tolerance
- Low disease potential
- Low mowing requirement
- Low fertilization requirement
- Very low water user, needing 1/4 to 1/2 inch each week
- Goes dormant during a drought without water, but revives as soon as watering is sufficient
Weaknesses
- Low or poor traffic tolerance
- Low or poor shade tolerance
- Easily invaded by weeds and other grasses in high-rainfall areas of over 25 inches, or when watered excessively
- Not as thick as other grass types
- Seed and sod are expensive
St. Augustine
Characteristics
- Coarse leaf texture, with light to medium green color
- Root system can extend down to 3 feet
- Varieties available in plugs, sprigs, and sod, with sod being the primary method
- Used for home or business lawns
- Goes dormant and turns tan in the winter when temperatures drop below 55°F
- Varieties include: Floratam, Raleigh, Palmetto, Delmar, Amerishade, Common, and TamStar
Strengths
- Establishes rapidly, grows quickly, spreads via stolons
- Above-ground stolons help repair drought-damaged patches
- Thrives in heat up to 105°F
- Goes dormant during a drought. The most drought-tolerant variety, Floratam, can go dormant for 3-4 weeks without dying
- Low to moderate mowing requirement
- Different varieties have a shade tolerance from moderate to excellent (but not deep shade)
Weaknesses
- Moderate traffic tolerance
- Very poor low temperature tolerance and is prone to winter damage
- Moderate to high fertilization requirement
- Moderate to high water user, needing 0.5 to 1 inch of water in a deep soaking every 3 to 6 days. Won’t hold its color without irrigation
- Some varieties more susceptible to chinch bugs, insect pests, and diseases such as gray leaf spot and brown patch
Zoysia
Characteristics
- Leaf texture from fine to medium coarse, with color from light to medium green
- Root system can extend down to 2 feet
- Varieties available in seed, plugs, sprigs, and sod, and is best established from sod
- Spreads by stolons and rhizomes
- Needs several hours of direct sunlight
- Used in residential and commercial landscapes, as well as in parks, sports stadiums, and golf courses
- Goes dormant and turns tan to brown in the winter when temperatures drop below 55°F. Stays greener longer than Bermuda and other warm-season grasses
- Most drought-resistant varieties are El Toro, Jamur, and Palisade (coarse textures)
Strengths
- Remains green during short drought periods
- Low to medium water user, needing 1 inch every 4-7 days
- Tolerates heat exceptionally well up to 100°F
- Goes dormant after a drought period of 30 days for 3-4 weeks without dying, and when water supply returns will green up again
- Underground rhizomes and above-ground stolons can repair damage from drought
- Good shade tolerance
- Tolerates foot traffic
- Lower fertilization requirement
- Coarse varieties require higher mower heights, but less maintenance
Weaknesses
- Finer varieties require more frequent and lower mowing heights
- Mower blades need routine sharpening to cut stiff leaf blades, and some varieties best mowed with a reel mower
- Slow to establish and spread. Sod has the fastest establishment
- Recovers slowly from wear and thinning
- Finer varieties have shallower root systems
- Not all varieties have resistance to diseases and pests
- Expensive
One of the most effective things you can do for your lawn is to keep your sprinkler system in peak operating condition. Call Smart Earth Sprinklers at (512) 694-1147 for the best in repair and maintenance.
