As the 2005–06 season commenced Watford manager Adrian Boothroyd, who had worked with Spring when he was first team coach at Leeds, brought the midfielder to Vicarage Road to be part of his reshaped team for a transfer fee of £150,000. Spring scored on his debut, coming off the bench to put in a late third in a 3–1 victory over Burnley on 20 August 2005. As Boothroyd's team flew high in the Championship, Spring, a regular in the team, scored seven further goals from central midfield by the end of January. However, he did not score again until Watford reached the play-offs in May, when he scored the third goal in the 3–0 victory over Crystal Palace in the first leg of the semi-final. Spring played in the 3–0 Championship play-off final win over Leeds United at the Millennium Stadium, with Watford earning promotion to the Premier League.