run to seed
Also, go to seed. Become devitalized or worn out; deteriorate, as in I went back to visit my old elementary school, and sadly, it has really run to seed, or The gold medalist quickly went to seed after he left competition. This term alludes to plants that, when allowed to set seed after flowering, either taste bitter, as in the case of lettuce, or do not send out new buds, as is true of annual flowers. Its figurative use dates from the first half of the 1800s.