Both team enjoyed periods of possession and were able to make advances up the field but neither were allowed many opportunities in the attacking circle.
It was late in the first half when Hikurangi did get a chance close to goal and were able to extend their lead when Morris converted from a goal mouth scramble.
Old Girls came out fighting in the second half but Hikurangi used their strength on the ball to retain possession and slow the game down.
Organ praised his team's season after the match, saying consistency and team work had taken them all the way.
"We've had one loss all season so it was a matter of being consistent and staying focussed [in the final].
"This whole season has been about team work ... we've got a lot of superstars but it's about being a team and trying to come together as a team."
Maungakaramea finished in third in the reserve A competition after they beat Whangarei Girls' High School 5-1 on Friday night.