However the tourists' will feel they dropped the ball after having the hosts' a parlous 72 for eight, after they had chosen to bat in favourable conditions. Zimbabwe were all out for 164 with New Zealand 32 for none at stumps.
The aggressive left armer Wagner took six for 41 off 20.5 overs, his third bag of five or more wickets in a test innings, with two wickets apiece going to fellow seamer Tim Southee - one with the second ball of the match - and left arm spinner Mitchell Santner.
Zimbabwe's batting was put to shame by their medium pacers Prince Masvaure and Donald Tirapano, who shared an 85-run stand for the ninth wicket.
Without that, Zimbabwe would have been just about dead and buried well before stumps on the first day of the series.
Wagner, as he has done in his most recent tests last season against Sri Lanka and Australia, worked the short ball hard and it paid a dividend.
Few of the Zimbabwe batsmen looked comfortable and three times Wagner struck helmets with his hostile bowling.
"It's a tactic of mine that's been one of our strengths, but it's more an option of trying to get players off the front foot, creating opportunities to see if we can get a wicket, and get some doubt in their footwork" Wagner said.
"With the wicket being flat you have to try some options to create results and luckily it worked."
Zimbabwe lost wickets in two key clumps - three for one in nine balls in the morning session reduced them from 35 for one to 36 for four; then they tumbled from 72 for four to 72 for eight, four wickets falling in 10 balls, including Wagner being on a hat-trick.
Only the tailenders' dogged determination prevented a ninth Zimbabwe test innings falling short of 100.
Before lunch Wagner, switching to around the wicket, created doubt in the batsmen's minds and they collectively looked uncomfortable as soon as the bustling seamer dropped the ball short.
There were some limp shots along the way while lefthander Sean Williams was seriously unlucky.
He was struck a nasty blow on the side of his helmet second ball by Wagner. After taking a couple of minutes to unscramble his mind and check his lid, Williams copped another flier next ball which ballooned off his helmet to be caught at short mid on.
Williams, who had tried to pull the ball, was understandably bemused to then discover he'd been given out caught. It was a shocker of a decision.
Zimbabwe's batsmen collectively didn't look up to the job in good batting conditions.
Masvaure and Tirapano were able to knuckle down as the pitch seemed to flatten and slow down. There was notable turn for legspinner Ish Sodhi midway through the second session.
Tirapano slammed a Sodhi half tracker into the stand at mid wicket and by the end of the innings he'd batted 171 minutes and faced 162 balls for his unbeaten 49, while Masvaure made 42 in three minutes' less.
They deserved the Zimbabwe ninth wicket record, but fell two short of the mark of the Strang brothers against Pakistan at Sheikhupura 20 years ago.
"Those two guys batted really well and showed a lot of patience and fight on an unresponsive wicket that was testing at times,' Wagner said.
He was understandably chuffed with his career-best return. His one previous six-wicket haul came in his last test, against Australia in Christchurch.
''It's a nice moment in your career," Wagner said.
''But just to get an opportunity to play test cricket again, and play well for your country is really pleasing."
