What does "hardy colors" here mean?

What does “hardy” here mean?
I looked up in several dictionaries but I couldn’t find a good definition for it.

There were about half a dozen men and Shasta had never seen anyone like them before. For one thing, they were all as fair-skinned as himself, and most of them had fair hair. And they were not dressed like men of Calormen. Most of them had legs bare to the knee. Their tunics were of fine, bright, hardy colors—woodland green, or gay yellow, or fresh blue.


I have never seen the word hardy used that way. He’s being poetic so that’s why you couldn’t find a good match in the dictionary. I think he means strong intense colors, like fully saturated colors.