The meaning of the idiom "Old trees blossom"

Old trees bloom, which means that Cycas rarely blooms, and it takes twenty or thirty years for old trees to blossom, so it is called "Cycas Millennium Flower"; Now refers to the new development of old things.

Novel: "The Old Tree Blossoms" by Fog Shadow. I always thought that I was very old, and I was selling my old age, but I didn't know that I was tender like an onion that day. I just made a background when he was reincarnated.