The home side also profited from turnovers as Ross Hay, playing his 125th game for the team, dominated the loose with excellent support from Dave Simpson, Josh Collier and, when he came on to replace No 8 Tevita Fifita, Ryan Long.
North Otago always looked dangerous out wide, where Greg Zampach and Lemi Masoe used their pace to attack Mid Canterbury.
In midfield, the power of Luke Herden and Faaitu Tuamoheloa caused all sorts of problems for the opposition defence, while fullback Billy Guyton was an elusive runner.
North Otago first five-eighth Ben Patston appeared to lack confidence and was hesitant at times, but he kicked three penalties and converted three of the five tries to take his points tally in Heartland rugby to 102 for the season.
Halfback Chris Lock, first five-eighth David Maw and right winger Chris Crichton were the pick of the Mid Canterbury backs.
Maw controlled possession expertly and his tactical kicking and accurate goalkicking kept his side in the game, while Crichton's blistering pace gave him two tries.
No 8 Pete McAndrew, lock Dan Dwyer, flanker Nick McKain and hooker James Carr had solid games, but their team could not match the finishing power of North Otago.
Carr picked up a yellow card four minutes into the game but Patston then missed two penalties.
One, from 53m out, had the distance but was just wide.
Eleven minutes into the game, North Otago went on attack and built up a three-on-one overlap but Herden decided to lob the ball to Zampach, Crichton intercepted and raced 80m to score.
Patston kicked a penalty soon after, and in the 17th minute, from a 5m scrum, Kilifi Fangupo broke on the blindside and Masoe came inside to score and put North Otago into an 8-7 lead.
Patston added his second penalty in the 27th minute and North Otago went to halftime with an 11-7 lead.
The second half started sensationally when, from inside North Otago's half, Maw angled a kick out to the wing and Crichton showed his pace to score.
A Patston penalty made it 14-14 before a Maw penalty in the 52nd minute put Mid Canterbury back in front 17-14.
Two minutes later, North Otago moved the ball wide, Fifita, Patston and Zampach broke down the left flank and Tuamoheloa scored out wide.
Then, from a lineout drive, Fifita moved the ball to the left on the Mid Canterbury 22 and Patston fed Masoe coming in off his wing.
The winger outpaced the defence to score, Patston converted and North Otago was out to a 26-17 lead.
Twelve minutes from fulltime, from a Mid Canterbury scrum, North Otago forced a turnover and, with a slick pass, Tuamoheloa put Herden in for a try.
Mid Canterbury hit back in the 75th minute when Maw put up a well-weighted kick which he gathered to touch down and convert.
North Otago had the final say when Simpson snapped up a loose ball and Herden was in for his second try.
In the Lochore Cup, third and fourth qualifiers Buller and Wairarapa-Bush will meet in the final in Westport after each caused an upset in the semifinals.
Buller beat Horowhenua-Kapiti 19-14 in Levin, while Wairarapa-Bush beat top qualifier King Country 21-17 in Te Kuiti.
Meads Cup Semifinal
North Otago 40: Lemi Masoe 2, Luke Herden 2, Faaitu Tuamoheloa tries; Ben Patston 3 pen, 3 con
Mid Canterbury 24: Chris Crichton 2, David Maw tries; Maw pen, 3 con
Halftime: North Otago 11-7
- Terry O'Neill
