go to seed

/G OW1 T UW0 S IY0 D/
verb
  1. 1

    (of a plant) To pass from flowering or ripening to the formation of seeds.

  2. 2

    (by extension) To deteriorate; to decline into an unkempt or debased condition.

Source: https://en.wiktionary.org/wiki/go%20to%20seed