late bloomer

noun4

1. •
   (figurative) A person who reaches puberty or who matures comparatively later than is typical.
2. •
   (figurative) A person who enters a romantic relationship or engages in sexual intercourse significantly later in life.
3. •
   (figurative) A person who achieves proficiency or success in a field significantly later in life.

   • He was a late bloomer, finding success at 40 in Luc Besson's 1988 film The Big Blue. — 2010
4. •
   A flowering plant that blooms later in a growing season than other flowering plants.