I once had a garden in which mint had taken over. It will annex as much territory as you allow it, and you can make only so much mint sauce or drink so many brandy smashes.
These days I keep my mint imprisoned in one of those old double concrete troughs they used to have in pre-1940s exterior laundries – known as wash houses. My mother had one into the early 1970s. Originally, she'd wash in one side of the trough and wind the washing into the other side through a hand-wringer consisting of two enormous rubber rollers clamped onto the dividing wall. Best thing ever. As children we used to try to catch each others' hands in the roller and wring their arm through. Nasty little brutes we were.
Most of the old troughs were smashed up and taken to the tip when washing machines came along, but visionary householders kept their troughs so that later generations could reuse them as plant pots. Their brass outlets offer better drainage than most of today’s planters, and the thick concrete walls don’t leach moisture like terracotta, which is next to useless in the heat of summer. That leaves plastic. And let’s leave plastic there.
The only inconvenience with your old concrete trough is its weight. If you happen to find one in the shed or behind the chicken coop in the backyard of the renovator special you just paid $800,000 for, you’ll need a truck to move it. I used a hand trolley to put mine into position and bricked under it to support it around the outflow pipe.
I found its concrete 'legs' in another part of the garden and now they lie flat in the soil behind a bed of ancient weigela.
And there's my mint in solitary confinement in the right tub of the old concrete wash house trough propped up against the shed in a sun-trapped corner of the back yard where the temperature can hit 50 celsius on very hot days. In the other tub lemon thyme, ordinary thyme, sage and oregano thrive and you never have to water them. Oregano can tend to take over if left on its own, but it is behaving itself in that company. On barbecue nights, I pick a sprig or two of each and throw them on the coals and make aromatic smoke signals and the neighbours' heads pop up over the fence. Have a mint julep. There’s the mint patch.