When the Gardeners sent a message to the Thirteenth Doctor, the begonia managed to make Graham take it into the TARDIS with him. There the begonia relayed the Gardeners' summonses but secretly also transmitted their location to Nightshade, enabling him to capture the TARDIS and her crew.
Before its betrayal became known, the begonia called Graham "Gray-ham, Giver of Water".
When the followers of Nightshade were transferred into the custody of the Gardeners after their spaceship plunged into a sun, the begonia was not among them. However, Graham had a premonition that they will meet again. (PROSE: The Secret in Vault 13)