Question

a late bloomer
1. Lit. a plant that blooms later than similar plants or that blooms late in the season.
  There are a few late bloomers in the garden, but by fall, we don't care much anymore about f lowers.
2. Fig. a person who finally develops a useful or superior skill or talents later than expected or desired.
  Joseph was a late bloomer, but turned out to be a formidable scholar in the long run.