She said the Rugby World Cup would be a priority on the calendar this month and next.
"We're going over to Waiheke in a few weekends and we had to make sure that the place where we were staying had Sky Sport on TV.
"We couldn't pick anywhere else."
Mrs Johnstone was unsure about Canada's chances of making it out of the pool round at this World Cup - they have only ever made one Rugby World Cup quarter-final, in 1991.
"It's a hard pool and the test games they've been playing, they haven't really been playing all that well."
However, in 2011 Canada did play a lot better than they had been leading up to the tournament, she said.
"So you never know what could happen at a World Cup, especially when you've got the passion there."
All of Mrs Johnstone's family are back home in Canada. She shares her love of rugby with her brother and her late father was also a fan.
Mrs Johnstone said interest in the game was steadily increasing in Canada.
"Because it is such a growing sport, people are becoming obviously more enthused about the World Cup now than they probably would have been 10, 15 years ago.
"I think it's hard because ... of course Canada is so big, so the players come from so many different places," Mrs Johnstone said. "So it's not like here in New Zealand where a lot of them can associate more with the players directly."
But as a Canadian rugby supporter, she has got used to standing by the team through thick and thin.
"Because it is a growing sport and they're getting better. They're nowhere near the All Blacks yet, but they are getting better, so I'll keep supporting them through to the end."
Cup super fans
Today: Canada
Will play: Ireland, Italy, France and Romania in the pool round.
Currently ranked: 18th in the world.
Team logo: An image of a rugby player over the top of a red and black maple leaf.
Team anthem: O Canada.
2011 Rugby World Cup result: Canada failed to make the quarter-finals after defeats to France and New Zealand, but beat Tonga and drew with Japan.
First international match/outing: Tour of Japan in 1932.