Little is known so far about the history of The Garden or their individual members but it appears Ex Nihilo is the leader of the group. The Garden's purpose is to plant seeds in worlds to enable them to become better worlds - even if that includes wiping out the inhabitants of that world and starting anew. They have recently turned the red desert planet Mars into a green and vegetative state.
The Garden's next target is Earth and they have begun planting their creationist seeds into various parts of the planet. The seeds have landed and caused massive destruction in Perth, Australia and Regina, Italy - killing almost 2 million people. This has attracted the attention of The Avengers who have arrived on Mars to oppose this new threat to humanity. It was later revealed that the Garden are part of the larger Builder Race. An empire of the oldest beings in the Universe, who have gone from creating to destroying everything they helped create.
The Garden and all it's individual members were created by writer Jonathan Hickman and artist Jerome Opena. The group first appeared in "Avengers World" in December 2012.