You could do that, or just pot up some and keep them in a different part of the yard.

I think some mints are more susceptible to rust than others. I overwatered my spearmint when I first got it and it had rust, but bounced back when I let it dry out and removed the affected leaves

Jan

nice one I seen on web that pores can trvel in air so was worried moved half to front garden and keep rest in back

40 mint plants... the mind boggles... :-)
Two of each would have been good to start with and once established would be EASY to propagate from division -- or stem or root cuttings!
I think before long you will have more mint than you know what to do with. Mints are like the Everready bunny of the herb world! LOL

There was only one place I could buy yhem from and they would not allow me to buy 1 at a time or buy one of each in a pack of 5 it was take 5 of one or nothing I tried to sell them and even give them away but no so I went and planted 30 out of the way