Posted: 09/02/2016 at 13:29
For me mint is best repotted every year......
Best divided in mid spring when divisions romp away. Pot up some small roots to grow on later in gh for late autumn use.
I too use john Innes or sieved soil mixed with mpc.
Never let it dry out in summer....it can suffer with mildew. I find it better to with a little shade in summer
I would never risk it in the ground.