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.
Mint will tolerate a wide range of conditions, including heavy soil. It prefers the wet and loves a bit of shade. With the rise in popularity over the past 20 years of Asian cuisine, many varieties of Asian mint have become popular, particularly Vietnamese mint. This is not strictly speaking a mint, as it is not actually part of the mentha family, but is instead is botanically known as Persicaria odorata (and sometimes, oddly, called Vietnamese coriander). Persicaria odorata is a little more temperamental than the common mint. It still enjoys shade and plenty of moisture, but it prefers freer draining soils and subtropical or tropical conditions. If you have a propagation house and are diligent with your watering you will find it will winter-over, but in the outdoor garden it is more of a perennial.
Both common garden mint and the Vietnamese varieties have lovely flowers, which, as well as the leaves, can be used in cooking. Since common mint is a cousin of the lavender, this should not be surprising, even if it enjoys almost completely the opposite growing conditions from lavender.
As a companion plant mint is hard to beat, unless you happen to be a parsley bush (again, there's always one), in which case you and mint will rub each other up the wrong way. This is because they have competing root systems that don't like each other. As a rule though, one - usually mint - will suppress the other.
In a cocktail, in a salad and in the classic mint sauce, fresh mint is a completely different proposition to its dried counterpart.
So, if you want to keep your mint "minty" for winter, freeze it with water in an ice cube tray. Save the dry stuff for rubbing on your lamb roast.