Antonyms of blossom:
decay, decline, downfall, bottom, nadir, shriveling, wilting, withering.
Examples of usage:
  1. Look at the French beans; they climb and blossom at the same time.
    "St. Peter's Umbrella", Kálmán Mikszáth.
  2. At this Gottfried blushed up to the roots of his gray hair, and murmured, What an idea to come into your head- I an old cripple, and this young blossom!
    "Blanche: The Maid of Lille", Ossip Schubin.
  3. " If you say 'got a cat' in school, Meg, I'm sure something will happen to you," warned Mother Blossom, bending over the sewing machine.
    "Four Little Blossoms at Oak Hill School", Mabel C. Hawley.