Mr Sexton showed the Times-Age the remains of a double-rolled cigarette found near the fenceline where he believed the fire originated. He said witnesses saw two people leaning against the fence before the fire started.
"It's just carelessness. People just don't think."
The rain overnight, about 20ml, was welcome, he said, especially after a dry period.
"The fire got to the rail tracks, and the next line of fire was a car wreckage place, potential for all sorts of things.
"We had the police talk to the owners, saying they may have to evacuate."
Featherston rugby players Kaleb Burt and Damien Sinclair said they ran over the road to stamp on the fire, but quickly realised it was beyond their ability.
"As soon as we tried, it just went up," said Mr Burt. "It was scary, with wind conditions like that. It just went up."
Earthcare manager Linley Thorburn said she was close to closing up the station when she was alerted that the green waste was on fire.
She said it was a "scary" blaze with the strong winds. "Everything is just so bloody dry at the moment."
The fire crew's efforts drew a large crowd of cheering rugby players and supporters from the Featherston and Puketoi teams, with one joking it made for pretty good "after-match entertainment".