catanddog wrote:salad day: an especially happy period of one's life ,or a period when one is young and naive
The second one. Although it would not be used incorrectly if you used the phrase as a description of the first.
The phrase is taken from Shakespeare's Antony & Cleopatra.
CLEOPATRA: My salad days,
When I was green in judgment: cold in blood,
To say as I said then! But, come, away;
Get me ink and paper:
He shall have every day a several greeting,
Or I'll unpeople Egypt.