There were two undoubted conclusions to draw from the CONCACAF Nations League final at the Sofi stadium.
The first is that the American male football team, which finished fourth out of four teams, is far from ready for the World Cup next year. The stadium, on the other hand, nailed its most important general rehearsal, deploying a carpet of hybrid grass which resisted the tension of four games in as many days.
“The land has gone beyond our expectations,” said Otto Benedict, vice-president of the stadium for the operations of the facilities and the campus. “While we were convinced that the grass would respond well to the level of play and activity, we were not sure of its resilience inside our building. In the past two weeks, the weather has been variable with rain and heavy humidity in the air, followed by wind and hot temperatures with sunny days.
“The grass was prosperous and adapted to our unique inner / outdoor environment in any way we hoped.”
This is important because Sofi tries something unique. When the stadium, the most expensive sporting place in history, opened its doors in 2020, it did with a field that was fine for the NFL but too narrow for football. And the grass was synthetic, which was also a non-no for a World Cup.
To bring things to FIFA standards, Benedict had to find a way to make the playing surface wider and how to cover the false lawn with real things.
The workers install a cash register panels as part of the hybrid grass of the Sofi stadium in February 2025.
(Angel Torres)
The first problem was actually the easiest to solve. For the matches of the League of Nations, the Sofi field was 72 wide yards – 2.4 yards too narrow for the World Cup – and the corners were unacceptably tight. To solve this problem, Benedict said that certain suites in the field and around 400 seats in the lower bowl will be temporarily withdrawn for the next summer tournament.
The installation and growth of natural grass sufficiently robust to resist eight games in 28 days were much more complicated and required a partnership between Sofi, FIFA and researchers at the University of Tennessee and the State of Michigan. The result was a series of surfaces stacked 28 inches above the NFL playground.
The height was built on a basis called “permavoy”, a sub-structure designed to support the field while allowing air and humidity to move under the root zone. It includes sand and permeable fabric lined with a hybrid grass carpet of fresh season cultivated in Lake Moses, Washington, transported by truck to Inglewood, then moved in strips four feet wide and 45 feet long.
The key part of the under-to-air point system consists of 100,000 square feet of black plastic boxes 2 feet by 4 feet which allows air to flow while allowing the water to be sucked in case of need. This allows oxygen to move under grass while preventing the field and the root area from becoming too wet.
It adds to the grass arranged inside the stadium, an additional 10,000 square feet are kept in a parking lot in case the worn sections of the field must be repaired. The temporary surface will remain in place thanks to a friend of women on April 5 between the United States and Brazil. The field will then be tested for traction and sustainability as well as for health before being removed. A new grass field of the green desert of the cool season will then be installed for the Concacaf Gold Cup this summer.
The surface of the World Cup, which will be improved with information collected during this month's test race, will be installed in April 2026, about two months before the opening of the US team World Cup at the Sofi stadium.
Workers are preparing a hybrid grass field at the Sofi stadium in February 2025.
(Kjell Gerber / Hollywood Park)
Technology is a major improvement in relation to how temporary grass fields were laid on artificial lawn for previous tournaments that used NFL stages, such as Gold Cup. The grass on these fields was often not stable and had wide and dangerous seams where height sections met.
“This is certainly better than a lot of the Gold Cup,” said Canadian goalkeeper Dayne St. Clair about the Sofi field. “You can certainly say that there was no separation in the grass and that he had time to grow.”
“It was interesting. It was a little different (from) what we are used to,” said US Tim Weah striker. “This grass is different. This is something we have to get used to. ”
The hybrid field, said Benedict, requires a crew of 30 to install and maintain, about double the staff necessary to take care of the surface of the Sofi matrix for the NFL games. The price of several million dollars on the ground will be paid by the host committee of the Los Angeles World Cup 2026.
“A hybrid carpet pitch of fresh seasonal carpet is the best system for our stadium,” said Benedict when asked what he had learned from the League of Nations. “The successful integration of our irrigation, sub-Air and Permavoy systems allowed us to trust and data necessary to validate this conception, in particular while we are preparing for the 2026 World Cup.”
Workers install a hybrid grass field at the Sofi stadium in February 2025 after the Final Four of the League of Concacaf Nations.
(Kjell Gerber / Hollywood Park)
