Plant Answers  >  Floratam St. Augustine Grass -- the BEST Grass for South and South Central Texas

Floratam St. Augustine Grass -- the BEST Grass for South and South Central Texas

Floratam St. Augustine grass was released by the Florida and Texas Agricultural Experiment Stations in 1972 as a SAD virus and chinch bug resistant selection. It has since been observed to be brown patch tolerant. Like other Florida types, Floratam is a vigorous, coarse textured St. Augustine grass variety. Floratam has a purple stigma color and is sterile. Stolons of Floratam are large, purplish-red in color with internodes averaging 3 inches in length. Leaf blades are wider and longer than common St. Augustine grass. According to James Beard, TAEX Turf Researcher - retired, test at A&M concluded it is the most drought-tolerant of all St. Augustine grasses.

Some feel that Floratam is not as cold tolerant as the common type found in Texas so preconditioning by use of Winterizer fertilizer (3-1-2 or 4-1-2 ratio) in the fall (October) is CRITICAL. Floratam may suffer freeze damage in areas north (cold) and west (dry) of San Antonio so the grass variety is especially suitable for all areas South of Highway 90 including San Antonio, Houston, Corpus Christi and the Rio Grande Valley.

Some feel that Floratam also lacks the degree of shade tolerance that other St. Augustine grass varieties possess but filtered light through live oak canopies offer the ideal growth environment.

We believe that the recommended Floratam St. Augustine is the best available for the diverse growing conditions of South Central Texas. It tolerates and even thrives in periods of excessive rainfall. A study of the drought tolerance of grasses entitled: "Comparative Intraspecies and Interspecies Drought Resistance of Six major Warm-Season Turfgrass Species" was conducted by S. I. Sifers and J. B. Beard at Texas A&M University.

Four years of field drought resistance studies were completed on grasses growing on a modified sand root zone.In the fourth year of the study, 29 bermudagrass, 2 seashore paspalum, 2 buffalograss, 8 St. Augustine grass, 6 centipede grass, and 11 zoysiagrass cultivars were subjected to 158 days of progressive water stress with no supplemental irrigations applied and less than 7.5 cm. of natural rainfall.Degree of leaf firing was used as an indicator of dehydration avoidance and post-drought shoot recovery was used as the indicator for drought resistance.Significant drought resistance differentials were found across the cultivars and among the species. Results were consistent with the first three years of the study among the bermudagrass, seashore paspalum, St. Augustine grass, and buffalograss cultivars.Among the centipedegrass cultivars only Oklawn fully recovered.

Leaf firing of all zoysiagrass cultivars was in excess of 50%. All recovered, except Meyer at 20 percent and Belair at 45% after 30 days.Excellent dehydration avoidance was seen in Floratam and Floralawn St. Augustinegrass. There were large variations in drought resistance among the five St. Augustinegrass cultivars. Floralawn and Floratam showed high green shoot recovery. They showed less than 50% leaf firing after 34 days of drought stress and recoveries of over 90 percent. However, Texas Common and Raleigh St. Augustine grass as well as Prairie buffalograss showed over 98% leaf firing and less than 20 percent recovery.The performance of Floratam and Floralawn was excellent throughout the study in terms of shoot color, turgidity, and uniformity. They were comparable to 609 Buffalograss.


St. Augustinegrasses (Stenotaphrum secundatum (Walt) Kuntze) are the most versatile of the warm season grasses. They thrive quite well in acid or alkaline soils, in soils very low in organic matter or on pure organic soils, in full sun or moderate shade, on poorly drained or well drained soils. St. Augustine grasses are the most salt tolerant of the warm season grasses and have relatively fewer disease and nematode problems.

A potential threat to St. Augustinegrass lawns is a mosaic disease of St. Augustinegrass called St. Augustine Decline (SAD) which was first observed in 1966 in the lower Rio Grande Valley of Texas. The disease agent, a virus, has spread throughout Southern Texas rapidly. The virus is known to be spread by infected vegetative plant materials and by lawnmowers; an insect vector is also suspected. Mosaic symptoms appear within a few weeks after inoculation. Under natural stresses the vigor of the grass declines and often results in loss of the lawn. No therapeutic control for the disease is known. Control is through the development of varieties resistant to the disease.

Accessions of St.Augutinegrass from Florida and other sources were screened for resistance to SAD in a greenhouse in 1968. The first disease resistance field trial in 1969 revealed that some accessions, even though resistant to mechanical infection in the greenhouse, became diseased in field situations. In Texas, accessions showing resistance to infection were test planted in St. Augustinegrass turf heavily diseased with SAD at Ft. Worth, San Antonio, Corpus Christi, and Kingsville in 1970, and Houston and Bryan in 1971. In the field trials, transplanted susceptible common St. Augustine grass became infected, and SAD symptoms were apparent in this cultivar after 30 to 180 days. Other strains or accessions became diseased at one or more locations in the state over a two-year period with the exception of Roselawn strains and 'Floratam,' which remained symptomless.

Floratam has exhibited resistance to SAD virus under greenhouse testing since 1968 and in the field after 24 consecutive months. Floratam resistance to infection and disease development appears to be vertical. This type of resistance can possible break down under specific stresses, such as changes in virus vectors or infection mechanisms, changes in the causal pathogen due to mutation for virulence, or development of new races or strains.

Independent laboratory and greenhouse trials in Florida and Texas, respectively, revealed that Floratam is resistant to chinch bug injury. In the Florida tests, Floratam was found to exhibit true antibiosis (life-destroying property) in that more than 50% of the chinch bug population died in confined tests.

Floratam St. Augustinegrass was found to be better than common for the following reasons:
1. It has resistance to SAD virus.
2. It has resistance to chinch bugs.
3. It is vigorous, establishes a ground cover rapidly, and has superior color.
4. It is superior to Texas common St. Augustinegrass in its tolerance to downy mildew, gray leaf spot diseases and brown patch fungus.
5. It is adapted to growing conditions in Florida and Texas.
All of these advantages would be desirable to Texas and Florida growers. The industry has needed a fast-growing, weed-resistant St. Augustinegrass. Floratam will fill this need.

Origin of Floratam

Floratam originated as a 1960 seedling of FA-23. Florida-23 was brought to Gainesville, Florida in 1953 from Belle Glade (where it was designated as Roselawn selection # 9) and planted at the turf research area at Bivens Arms. Change of location of turf research area resulted in the movement of FA-23 and 43 other seedlings and selections to the Horticulture Unit in 1960. Seeds were collected from these 44 St. Augustine clones, and 160 seedlings were established. The original selections plus the 160 seedlings were evaluated thoroughly. In 1965 the poorer strains were discarded. FA-23 was one of the selections eliminated at that time. Seventeen seedlings were established from FA-23 and 10 survived the 1965 eliminations. Four of the 10 seedlings of FA-23 were found to be resistant to SAD. No other selection or seedling produced offspring with such a high frequency of resistance types to SAD virus. The pollen parent of Floratam is not known.

Taxonomic Description

Floratam is a stoloniferous , relatively fast growing St. Augustine grass. Culms are branching and highly compressed with flowering shoots 30 to 45 cm tall. Stolons are very large and are purplish red; internodes average 7.5 cm in length. Blade length averages 9.8 cm as compared to 11.4 cm for Roselawn. Blade width averages 9.3 mm, which is wider than other commercially available St. Augustinegrasses. Leaf color is better than common St. Augustinegrass.
The collar is continuous, white, wide at the margins and narrowing toward the midrib, and is petiolated. Auricles are absent. Edges of the collar contain numerous long hairs continuing 6 mm down the edge of the sheath and party over into the collar. The ligule is a continuous fringe of hairs about 0.4 mm long. Leaf veination is obscure except that the midrib is prominent on the underside. Leaves are folded in the bud and somewhat V-shaped to flattened when mature. The inflorescence is a long fleshy raceme with imbedded spikelets.

Growth Characteristics

Floratam is a fast growing cultivar that compares favorably in growth rate with common St. Augustinegrasses. When planted in lawns infected by SAD, Floratam grew rapidly and covered the surrounding area faster than the other varieties in the test. The high vigor of this grass results in excellent week competition. It has good tolerance to the herbicides which are recommended for controlling week competition. It has good tolerance to the herbicides which are recommended for controlling weeds in St. Augustinegrass. Leaves are unusually wide, which results in a coarse texture when compared with other cultivars of St. Augustine grass. This grass has tolerance superior to Texas common St. Augustine in the reaction to downy mildew, brown patch fungus, and gray leaf spot. Floratam and common are both susceptible to rust.

Insect Evaluations -- In independent laboratory and greenhouse trials in Florida and Texas, respectively, Floratam was found to be highly resistant to chinch bug injury. Chinch bug mortality on the Floratam averaged 60% compared to an average survival of 93% of the chinch bugs on the other named cultivars. These data indicate that Floratam, exhibiting true antibiosis, is resistant to chinch bug injury.

Grass clipping yields of Floratam compared favorably with common. The tolerance of Floratam to SAD virus makes this grass an extremely important addition to the St. Augustine grasses commercially available. It offers control to the disease existing in Texas, Louisiana, and Mexico.

Floratam will cover an area completely in one growing season when sprigged in 1-foot rows 1 foot apart on prepared seed beds. When plugged into diseased St. Augustine turf at this rate, it will cover in approximately one year. When a 2" to 4" ribbon is left in a sod field, regrowth should be faster than presently available commercial varieties.

The color of Floratam is better than both common and Roselawn. Stolon are purplish red with long internodes. This is an undesirable characteristic only when the grass is covering an area. After a sod is formed, the wide blades completely cover the stolon ana stolon color is not evident. Internode lengths are shorter after a sod is formed.

Floratam survived better than other varieties when mowed as low as -inch weekly, primarily because of good vigor. This grass performed better and had fewer weeds when mowed weekly at 2-inch height-of-cut. Cold tolerance was increased as the mowing height was lowered for all St. Augustinegrasses.

Home Lawns and Other Turf Areas -- Soil preparation before planting is very important to the success of a new lawn. All old vegetation should be removed and the surface uniformly graded and free of debris.

Planting -- Spacing of rows and sprigs in rows from 12 to 24 inches apart is recommended. Wider spacing takes longer for coverage but should result in more planting material for the second and third expansions.

Plugging is an excellent method of propagating St. Augustinegrasses but requires more planting material. Usually, 2-inch square plugs are dropped into an open furrow. Heavy rollers are used to close the furrows around soil plugs. A high rate of survival can be expected using this method because an established piece of sod is used and rooting time is eliminated.

Lawns can be plugged or sprigged as recommended above; however, solid sodding is recommended over both sprigging or plugging. Extra cost of solid sodding is usually more than compensated for in having an instant lawn, less soil carried into the house, savings in weed control, etc.

Maintenance Recommendations -- During establishment mow Floratam every two weeks at a 3-inch height-of-cut. Watering during establishment is very important, especially for sprigged areas. Never allow the surface of a newly sprigged area to become dry. This will necessitate daily waterings unless rainfall fills the need for the day. Plugging and sod planting to not require as frequent watering as sprigs; however, these areas should never be allowed to dry out.

Where sodding is the method of propagation, the addition of top-dressing to fill in between sod pieces and to level the area is recommended. Top-dressing should be the same soil as the sod is laid on. Do not use white or yellow sand unless that is the same type of soil being sodded.

Maintenance of Established Floratam

After a good turf has become established, good maintenance practices will result in a dense, weed-free, uniform turf with a minimum of problems. Good maintenance involves proper mowing, fertilizing, watering, and control of weeds, nematodes, insects, and diseases.

Mowing -- Floratam should be mowed weekly at a height of 2 inches using a reel type mower during the period from March through November. During winter months less frequent mows will be required because the growth rate is slower. Maintain the 2-inch height-of-cut during this period. Sharpening the blade several times during the year will result in a better cut and do less damage to the turf.

Fertilization -- Floratam is a vigorous St. Augustinegrass that responds to fertilization, especially nitrogen. Nitrogen fertilization will produce a dense turf with excellent color. A complete analysis, slow-release formulation fertilizer such as 19 -5 -9 is recommended in March -April followed by a 3 -1 -2 or 4 -1 -2 "Winterizer" -ratio such as 15 -5 -10 or 20 -5 -10 in September or October.

Watering -- The best rule-of-thumb for watering Floratam is to start irrigating as soon as the first symptoms of wilting are observed.

Update coming on drought-tolerant grasses
Jerry Needham Express-News
December 30, 2006

Beginning New Year's Day, developers will be limited to planting grass from an approved list of drought-tolerant varieties when they build a house or shopping center in San Antonio.

They might want to wait a week.

San Antonio Water System officials said they'd wait to update that list until they meet Friday with researchers from Texas A&M University and the Turfgrass Producers of Texas.

The researchers subjected 25 grasses - nine zoysias, eight Bermudas, seven St. Augustines and a buffalo grass - to drought conditions to see which would survive.

The good news is that about a dozen varieties recovered fairly well after going without water for 60 days.

The bad news for North Side homeowners on rocky soil is that all the grass planted in shallow soil died of thirst.

"Everything on 4 inches of soil died - even the Bermuda grasses," said Karen Guz, SAWS conservation director. "That's disconcerting for people who live up on the edge of the Hill Country and have less than 4 inches of soil under their grass."

Half the replicated plots were planted on deep native soil and the other half on 4 inches of soil underlain with a plastic liner to simulate a city ordinance requirement for 4 inches of soil under grass at new developments.

A 5,000-square-foot automated rain-out shelter covered the plot during the infrequent rainfall of the imposed drought, which started in late July.

Researchers had two measures for how well each grass fared after the drought - percentage of the area with living grass (live cover), and its uniformity, after 60 days of recovery time, Guz said.

"The range in live cover goes from 100 percent to 4.3 percent," she said.

Guz said that although she received a copy of the study results Thursday, she wants to discuss them with the partners before deciding what grasses should land on the approved list.

A list already exists that is based on previous research and expert recommendations for semi-arid areas. Developers will be within the law if they pick from the old list between Jan. 1 and when the list is updated.

However, most developers hesitate to put in lawns in winter anyway, usually waiting until spring.

"What we're debating here is whether 60 percent recovery is OK after two months, or should we go up to 80 percent recovery," she said. "The question becomes, would a homeowner feel they needed to replace their grass if only 60 percent of it is alive two months after the drought ends."

She said that if 60 percent recovery is set as acceptable, 13 varieties make the out.

"Among those varieties, you'd have lots of Bermuda, several well-known zoysia, one buffalo and one St. Augustine variety," Guz said. "If the cutoff goes up to 80 percent, then none of the zoysia varieties make it, and zoysia is a pretty popular grass."

John Cosper, executive director of the Turfgrass Producers, said he feels some grasses should be cut a little slack on this study because of several factors.

"August was the hottest on record in San Antonio, so humidity was very low during the imposed drought," Cosper said. "There was a 23-day delay in starting the drought to make sure the rain-out shelter worked. That led to a lot of cold temperatures almost down to freezing during the recovery period. And the zoysias were mowed at much higher heights than they normally are, which I think hampered their recovery."

The study is going to be repeated this summer, and Cosper said there will be discussions about possibly changing a couple of the parameters.

Guz said SAWS officials are "inclined, this first year, to go conservative in terms of allowing the zoysias, knowing that by ordinance we can change the list after we do the replication."

She said several findings stood out.

"The Bermudas hands-down performed better than anything else," Guz said. "So if you've got sun, that's the grass to have. This was a full-sun test; we didn't look at shade situations.

"The one St. Augustine grass that did well Floratam - has a reputation for poor tolerance for extreme cold," Guz said, adding it might be OK for those in South San Antonio but not for those who get lower temperatures in the higher elevations of the North Side.

Guz said it's clear from the study that for grass to do well without a lot of supplemental watering needs at least 6 inches of soil.
"The lesson we're learning from this is that soil is incredibly important," she said.

To encourage better soil care, she said, SAWS from next month through April would offer a rebate to customers who put down a compost top dressing and aerate their lawns. Those with lot sizes of 5,000 square feet or less can get a $100 rebate, and larger lots can earn a rebate of $150.

Hardiest Grasses

Some grasses are tougher than others. A study of turf grasses showed some varieties recovered well with 60 days of care with no water. The San Antonio Water System will update its list of approved grasses for new development after consulting this week with researchers.

Variety % Recovery Uniformity*

Celebration Bermuda 100.0% 9.00

Grimes EXP Bermuda 100.0 9.00

Common Bermuda 98.8 9.00

GN1 Bermuda 98.8 9.00

Tifway 419 Bermuda 98.8 9.00

Tex Turf Bermuda 97.5 9.00

TifSport Bermuda 97.5 9.00

Buffalo Grass 95.0 9.00

Floratam St. Augustine 88.8 8.50

Empire Zoysia 71.3 8.50

Palisades Zoysia 71.3 8.50

Jamur Zoysia 68.8 8.25

El Toro Zoysia 62.5 8.50

Premier Bermuda 57.5 7.25

Common St. Augustine 55.0 6.00

Palmetto St. Augustine 51.3 4.75

Amerishade St. Augustine 42.5 4.50

Delmar St. Augustine 37.5 4.75

Cavalier Zoysia 27.5 6.75

Raleigh St. Augustine 25.0 4.50

Emerald Zoysia 25.0 7.25

Sapphire St. Augustine 17.5 3.00

Zeon Zoysia 17.5 6.75

Zorro Zoysia 15.0 6.00

Y-2 Zoysia 4.3 3.00
* Measure from 1 to 9 of how widespread growth is.

Source: Texas A&M University*s Cooperative Extension


After sending this to Dr. Jim McAfee, Turfgrass Specialist for the Texas Cooperative Extension in Dallas, I received this response:

Jerry, this information is definitely interesting. Outlined below is how our Georgetown drought study went. This rating is the amount of turfgrass left in the spring, after three full years of no supplemental irrigation on the plots.

Turfgrass % coverage
609 buffalograss 98
Top Gun buffalograss 85
JaMur zoysiagrass 70
Crowne zoysiagrass 40
Tifway 419 35
Common bermudagrass 5
El Toro zoysiagrass 3
Palmetto St. Augustinegrass 2
Floratam St. Augustinegrass 1
Raleigh St. Augustinegrass 0

Jerry, a couple of notes on our drought study.

1. It was not replicated.

2. The Floratam actually was doing almost as good as the buffalograsses until the last winter. Freezing temperatures killed out the Floratam, not drought. Even though the plot was dead in the spring, it was still a thick stand of Floratam.

3. In our study, the first grasses to show drought injury or go brown were all the zoysiagrasses, especially the fine textured zoysiagrasses. Milt chewed us out, saying we didn't give the zoysiagrasses enough time to get established. However, in my mind if a grass can't get established from sod in 10 months, then I question how good is it.

4. I was surprised by the results on the bermudagrasses. I thought that they would hold up a little better.

5. In the first year, the summer was very hot and dry. By September, most of the grasses in all the plots looked dead or severely thinned out. However, the Georgetown area received about 7 inches of rainfall that next winter and the next spring, all turfgrasses recovered 100%, including the three St. Augustinegrasses.

As to the current study, I am a little surprised that all the grasses died in the 4 inch soil test. I know some of the guys involved with the project believe that heat (the black plastic) also played a major role in the grass dying. I know I have seen plenty of buffalograss and some bermudagrass survive in less than 4 inches of soil for longer than 60 days. Don't get me wrong, I would like to see at least 6 to 8 inches of soil were possible for growing turfgrasses.

Jim McAfee

COMMENT: Notice the McAfee #2 comment: *2. The Floratam actually was doing almost as good as the buffalograsses until the last winter. Freezing temperatures killed out the Floratam, not drought. Even though the plot was dead in the spring, it was still a thick stand of Floratam.*
This means that Floratam is cold hardy if well-cared for going into the winter. This means that a *Winterizer* fertilizer with a 3-1-2 or 4-1-2 ratio should be applied in October (See: and an inch of water should be applied to lawn grasses every two or three weeks during the winter months in lieu of adequate rainfall.

If Floratam is *conditioned* for winter temperatures, cold damage in San Antonio, Houston, Corpus Christi and in the Rio Grande Valley should not be a problem. This explains why Floratam sod withstood the extremely hard freeze of 1983 when temperatures dropped to 6 degrees F. and was below freezing for weeks at a time. This same Floratam withstood the hard freeze of 1989 when the temperatures dropped to 12 degrees F. and stayed below freezing for a long time. Both of these freezes destroyed the Texas* citrus industry in the Rio Grande Valley but did not significantly damage Floratam St. Augustine sod in the northwest side of San Antonio.

Floratam St. Augustine Grass -- the BEST Grass for South and South Central Texas (PDF)



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