The green vine blossom is obtained by planting a Green blossom seed in a Vine flower patch. There is only one Vine flower patch and it is located in the herblore habitat. It is the flower required to attract cannibal and carrion jadinkos to the herblore habitat. 3 green vine blossoms can be used as payment to the Zombie farmer for tending your erzille seed.
There is currently a bug where players must wait until the green vine blossom is fully grown for the allocated god jadinko to appear, or for requirement notifications to appear in the chat box.