All you need in one mint in a container. It'll fill that whole container quite quickly. My spearmint plant in two months turned into about 30+ plants from runners. Maybe even 50+. There are so many new plants that I have to continue to thin it out or it would smother itself. That's just one plant. I could only imagine 3. Even the individual mint stems are self dividing without even having to be pruned. Some stems having about 10 stems growing out of them. I have to prune it everyday. As you can see, just one plant, is much more then enough.

I don't suggest mixing them. Not that I think there would be anything wrong with it. But they would just end up tangling amoungst eachother in an unattractive fashion. I have spearmint in on container, lemon balm in another, and chocolate mint in another. They are all in balcony style containers, planted in the middle so as to allow even spreading. This is working fine for me.

Plant any 3 you like. If one seems to take over cut it back once. If it is still a space monstor, pull and put in its own pot. Replace with something else. Repeat until you are happy with the results.

I do mostly container gardening and move mint plants (and others) around all the time. Mints are the hardiest and most forgiving of plantsl.

jan

I had chocolate mint,sweet mint, and spearmint in a container last year. It got very crowded by the end of the season, but I was only planting it for a year and not intending to overwinter.

Too many varieties in one pot, IMO.

Even if they were compatible and get along, they will get inter mixed because the roots are not restraints. Also the one with aggressive root system will eventually over power the others. Just the battle for survivor, nothing personal. LOL