I don't have much to say in regards to packing it...but make sure you can even take the plants to Vietnam. Many countries have restrictions on bringing in live plant material.

Ampersand is right....I'd be very surprised if Vietnam will let you just carry live plants into the county without permits. I know if you were coming to the U.S. it wouldn't be nearly that simple and probably not even possible. You might have much better luck just packing them very well into a box and sending them via some international package delivery service (fed ex, DHL, etc). But even then you'll be asked if the package contains live plants and fibbing about it could get you in some real trouble. I certainly wouldn't risk Vietnam prison for a few figs. You can probably google Vietnam agriculture importation or the like and find out how to get permission, go through quarantine, etc. Good luck...and be careful. You don't want to get stopped at customs with undeclared live plants! I once accidently brought an apple into the U.S. on an international flight and when they found it they literally treated it and me as if it was a bomb!! They took it extremely serious and I'm lucky I didn't end up with a huge fine. good luck.