Dandelions are a perennial plant. They have lots of growth and flowers in the springtime. During the summer, they bide their time waiting until the cool fall weather arrives. They will start growing again and making food reserves to be stored in their taproot for the upcoming winter and spring. Fall is the best time to control dandelions due to the movement of food to the root. Dandelions are one of the earliest flowers and pollen sources in the spring for honeybees and solitary bees. Leave a few around to help our pollinator friends. More information on dandelion control can be found at this link from K-State Research and Extension.
hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/Dandelion.pdf