Well, it’s when the plant bolts into rapid growth and goes straight to flowering. The plant goes into survival mode and goes to seed.
Hot temperatures will trigger bolting in cool season greens, such as arugula, mustard greens, romaine, beet greens, and lettuce. other plants known to bolt are beets, broccoli, cilantro, basil and dill.
Can You Eat it After Bolting? No. When this happens, the flavor turns bitter and the leaves tend to get smaller and tougher. At this point it is inedible.
But you can prevent bolting....
How to Prevent:
Keep the water in your AeroGarden bowl cool.
If the water feels warmer than room temperature, add cold water and or ice cubes to the water bowl.
Very rarely bolting can be temporarily reversed or slowed down if you catch it early enough and trim off the flowering stocks. This can give you more time to harvest before it becomes inedible.