Who started the tradition of wearing green on Saint Patrick's Day?

Answer 1

The wearing of Green stems from the ancient Celtic practice of wearing green during the Vernal Equinox to celebrate the rebirth of the Earth. When Christianity invaded Ireland, many of the Irish traditions were adopted into practice, to make conversion easier. Saint Patrick included using bonfires and adopted the symbol of the sun onto the cross, creating what is now known as the Celtic Cross. Since the local Pagan population was hesitant to give up wearing green, that too was adopted. It should be noted that St. Patrick's original color was blue.