New cultivar debuts in Houston

Photos courtesy of the Houston Astros.
This view from above the seats shows the pattern across the outfield.

In November 2008, the first harvest of the new cultivar, Platinum TE paspalum, found its home on the field of Minute Maid Park in Houston, Texas. The Astros’ director of major league field operations, Dan Bergstrom, oversaw the installation of the sod.

“The Astros ground crew has embraced the challenge of keeping a beautiful stand of turf under the roof of Minute Maid Park,” says Bergstrom. “We expect to keep our playing surface in top-notch condition for our players, and we’re excited to have the latest technology and turfgrass genetics with our new Platinum TE paspalum.”

New turf

The new Platinum TE paspalum is an introduction of Turf Ecosystems, LLC, where principals Dr. Ron R. Duncan and Tim Hiers aim to develop new turfgrass cultivars better suited to performance expectations and environmental limitations. The characteristics of the new cultivar that most appealed to Bergstrom were its dark green color, wear tolerance, and, especially, its tolerance to shade. “The paspalums also have the environmental advantage of tolerance to salt water or effluent water. Though we’re currently irrigating with domestic water, having the capability to use other water sources fits well with the Astros’ overall green movement,” Bergstrom says.

While normally he’d want to put the new cultivar through on-site testing, the time was right to make the change. His five years of managing paspalums, previous experience working with Dr. Duncan, and the research data on the new cultivar combined to create the comfort zone to move forward.

Arrangements were made with the sod producer, Phillip Jennings Turf Farms LLC, in Soperton, Ga., and the field was planted in November 2007. Bergstrom’s testing for this field conversion consisted of three trips to Soperton to observe the grow-in. The sod’s soil profile has a high sand content, closely matching the ballpark’s original USGA spec field with its 10-inch profile of 90 percent sand and 10 percent peat. Bergstrom says, “We’ve previously worked with sod grown on native profiles with 88 to 90 percent sand content, and we’ve never had a layering or drainage problem. We do aerate quite a bit to open it up.”

The harvest is just beginning. Note the different color of the surrounding grass that was not protected from the cold. It was still below freezing when the harvesting started.
The Platinum TE Paspalum is looking good as the harvest process moves forward.
The new sod as it appeared in early December.
The outfield pattern is dynamic with the deep green color of the new Platinum TE paspalum sod

The conversion

For professional baseball, it’s not unusual to replace the outfield turf every three to five years and the infield turf annually. Bergstrom had tackled a complete resodding twice during his five years in Houston when the baseball schedule, event schedule and roof closure combinations required grass replacement. Each time, he’d had only a 30-hour window to complete the project, with team play resuming four or five days later.

For this project, he’d planned on two weeks of field preparation with the sodding beginning around December 1. The extended period of cold temperatures predicted for Georgia moved everything up a bit, consolidating the total conversion to one week.

He says, “For the past several years, we’ve reduced our mowing frequency to every two or three days. That allowed the grass leaf to elongate so the increased surface could intercept more light. As the plant stretches for the sunlight, the crown of the plant stretches up, too. We’ve topdressed about 1/16 inch at least once a month to compensate for the elongation. Over time, the organic matter has reached a good level, so we always topdress with straight sand.”

King Ranch Turfgrass took out the old sod and installed the new, and Landscapes Unlimited handled all the laser work.

Bergstrom says, “Our topdressing had raised the infield. During the conversion process, we removed a couple inches of the infield profile to lower it back to the original level. The only thing needed on the infield dirt was to rototill it and remove a bit to match it to the turf level. Overall, the rototilling took one day and the laser grading two days. With all the edges on the baseball field, that process was still going on while we were installing the sod.”

Bergstrom flew to Georgia to be there for the first day of the harvest. He says, “We didn’t make any increases in the fertility program prior to the harvest. Shipping across the country, we wanted the turf to come from the farm pretty lean and as tough as possible. The Sea Isle had been hard to harvest in big roll form during the off-season, which is when we’d need the most sod. The roll would come apart and put more seams down than we liked.”

They used a total of 18 trucks, harvesting six trucks a day and laying six trucks a day. “We used refrigerated trucks kept at 38 degrees,” says Bergstrom. “The sod came up with no heat in the rolls and remained cool, so there was no desiccation.”

Prepping for use

By the first part of December, the new sod was putting out top growth and developing some rooting. Four weeks of limited on-turf traffic had been planned to give the sod some growing time.

 “We do get year-round use and have added a few more events to the calendar each year. The Astros own 40,000 square feet of Terraflor and we have a stage on wheels that we can put on the warning track, so we’re well-prepared,” says Bergstrom.

Bergstrom started cranking up the fertility program on January 1. He says, “We’ll stick closely to what’s been working, a basic granular N-P-K once or twice a month, supplemented with extra potassium in K-Mag. We’ll make a couple adjustments based on Dr. Duncan’s recommendations, adding some gibberellic acid to help the rooting and watching the manganese to keep those levels up. I like to keep the fertility consistent and strictly controlled so I’m better able to monitor the response. It helps to have that consistency when we deal with so many other variations in traffic and the roof and the weather.”

Bergstrom plans to continue his aeration program, using small, solid tines or a .5-inch star tine on the infield about once a month, and walking the outfield with the star tines. He’ll add heavy core aerification in October after the baseball season is completed.

This view toward the outfield of Minute Maid Park shows the extended shaded area.

He says, “The paspalum never goes dormant because we can close the roof to protect the grass. With the Sea Isle I, we had done some overseeding with perennial ryegrass, sometimes in November before Christmas and sometimes the first of March for Opening Day, to compensate for the wintertime wear. We don’t expect to need that with the Platinum.”

He does have 4,000 square feet of the new cultivar in his on-site sod nursery for small repairs. Bergstrom says, “We saw the increased density as soon as the new sod went down and hope it will lead to the wear resistance we’re after. While we expected better color, the Platinum in December was greener than the Sea Isle I in July. The people that see our grass every day were amazed at how green it was. We’re looking forward to a great season.”

The author is a contributing editor for SportsField Management. To contact her, e-mail