Tom McKeon was giving evidence at an inquiry probing claims of child abuse in the care system dating back to 1945.
Allegations of physical abuse made by former residents against some former staff there have been denied.
Mr McKeon said he only ever saw one incident where a teacher pushed a pupil against a wall.
Mr McKeon, who founded Les Chenes in the 1970s and worked there for ten years, said he had reprimanded the member of staff at the time and warned him such behaviour risked assault charges.
He moved on to other education jobs in the 1980s, then was head of education in Jersey from 1997 until he retired in 2007.
Les Chenes closed in 2003.
Mr McKeon told the inquiry in later years it could not treat teenagers being sent there with "deep psychological problems".
A secure school for troubled teens "crumbled" as drugs took hold in Jersey, according to a former education department director.