Dryads and their limitations

I'm writing a fantasy novel and the main characters are dryads! Woohoo!

The problem is though, I need them to be able to leave their grove, and everything I'm reading says that's impossible. Is it really? Would they die if they tried to leave? Are there any stories about dryads relocating to a different grove?

I mean, I'll do whatever I want, cause fantasy novel. But still. Would like to be as accurate as possible.

(Not sure if this is considered a "homework" question, so I apologize if it is!)