>>2109332usually when edible plants grown for their vegetation and not fruit start to put out flowers they have outgrown the tender sugary period where they taste best.
Vegetables that begin to go to seed become woody and the energy is drawn away from the bulb and toward the flower and future seed. Hard neck garlic for example needs to have their flowers (called garlic scapes) picked off when they begin to appear before they go to seed so the bulb can retain energy and become big. You can also eat the scape if you get it early it is more tender as well.