IMO- i would just keep them in a small solo cup.
Do what they do for Bonsai Plants, trim the root system.
You can cut off half the root system off.
You can also top the plant if it gets to tall.
Doing both you should be able to grow a Bonsai Plant for as long as you want to.
I can see bad things happening if you put them in the fridge. You cool the root system it slows the plant down, but the temps might be to cold, with colder soil temps you get into locking out Nutrients because of the cold soil. You might kill every leaf on the plant. Marijuana can handle cold temps, it's the period of cold that will kill them.
Good Luck on your Grow.