A week earlier, Wairarapa-Bush had suffered a 24-0 loss to the same opponent, but come semifinal time it lifted its game.
North Otago coach Nigel Walsh had expected a tougher encounter, and he was correct.
"Whilst I was rapt with the win last weekend we knew it would be a different story this week," Walsh said.
"Both teams tried to counterattack each other and, as a result, there were a lot of mistakes from both sides.
"[In the first half] we were creating opportunities but we weren’t finishing them off.
"We did improve in the second half and looked sharp. But it was a topsy-turvy game. We’d score, they’d come back and in the last seven minutes they scored a converted try and kicked a penalty to take the game.
"But there was no lack of effort from our boys. They put up a good fight in very hot windy conditions."
North Otago flanker Junior Fakatoufifita opened the scoring with a try in the 12th minute and fullback Josh Buchan kicked the first of his three conversions.
Wairarapa-Bush first five-eighth Glen Walters replied with a penalty, and on the stroke of halftime halfback Daryl Pickering slipped the defence to score.
Walters kicked his second penalty three minutes into the second half to extend the lead to 13-7.
North Otago regained the lead when winger Matthew Vocea touched down and Buchan converted.
But almost immediately Wairarapa-Bush midfielder Michael Lealeva’a scored.
North Otago struck back when replacement number eight Jake Greenslade scored.
The visitors led 21-20 with about 10 minutes remaining. However, it was the home side which had the last say.
Replacement winger Epeli Rayaqayaqa scored. Walters converted and added a penalty two minutes from fulltime to seal the victory.
Wairarapa-Bush will meet Horowhenua-Kapiti in the Lochore Cup final after Horowhenua-Kapiti defeated Mid Canterbury 34-24.
In the Meads Cup, Thames Valley upset favourites Wanganui 17-7, while South Canterbury dispatched King Country 58-21 in the other semifinal in Timaru.
- Terry O'Neill
Heartland Rugby
Semifinal
Wairarapa-Bush 30
Daryl Pickering, Michael Lealeva’a, Epeli Rayaqayaqa tries; Glen Walters 3 con, 3 pen
North Otago 21
Junior Fakatoufifita, Matthew Vocea, Jake Greenslade tries; Josh Buchan 3 con
Halftime: 10-7