As far as useful plants go, nothing is quite so maligned as the poor old common mint. The connection between the plant and the phrase implying something is near new or "flash", which has woven its way from the Roman temple of Juno, where new coins were "minted" to every second-hand car yard, is a tenuous one. I can't for the life of me find the connection between something that's "mint" and the mint in my garden.
The common mint is part of the mentha family of plants, which has hundreds of varieties, many of which are so highly cultivated it's hard to see where one strain starts and another one ends.
The most common to New Zealand palates are the spearmint, peppermint and spicata varieties, which grow in just about every garden in the country. The trouble is, once they get going they are quite invasive, especially around waterways or in marginal shady areas. If you plant mint in your garden it can take over, vigorously spreading through a network of underground runners. As anyone knows who has tried to rip them out, these can defy even the most ardent attempts to remove it.
But in saying that, mint's strong, fresh flavour and easy growing makes it as popular now as it ever has been. The leaves of mint are pungent so there is no need to have a massive plant. So to restrict its growth I recommend getting a sturdy container, removing the bottom from it and planting both the mint and the container into the ground.