The R's are bottom of the Premier League and are without a win all season. As a result, Hughes's future at Loftus Road has come under intense scrutiny in recent weeks.
However, Marsh feels that the Welshman should be given a little more time to prove his worth.
"If I was the owner, I would sit down now and say 'Mark, I am going to give you four games," Marsh told BBC Sport. "I would say 'We are in desperate trouble. If we don't improve our league position in four games, I am going to have to make a change.'
"There would still be 22 games left in the season if you made a change in four games' time. There would still be enough games to turn it round.
"At least that way everybody knows the situation - the players, the managers, the fans."