Guild Wars 2

Ok, so I just checked this. You can indeed get the vial by talking to the geode vendor in Dry Top’s Centaur Camp. The item also works as intended, i.e. you can upgrade it in the Mystic Forge to the needed Plant Food.
What confuses me is why we don’t even get a hint where we might find the item we need once we get the Cultivated Sprout, despite the fact that we got a whole set of the needed items for the back piece in Dragon’s Reach Part 1.

You can get the item you need from the geode vendor in Dry Top’s Centaur Camp by talking to her (It’s a talking option).

https://forum-en.gw2archive.eu/forum/support/bugs/Missing-Item-from-LW-S2-Taimi-and-the-Asura/first#post4288160

First of all, I AM aware of the fact that the seeds for the back piece got swapped out, but after consulting with someone who made their Mysterious Vine after today’s patch, I realized that we missed a crucial item.
It’s the item we should have gotten after the mission “Taimi and the Asura”, and it gets purified to the Vial of Mending Oasis Water you need for the Package of Oasis Soaked Plant Food.
It seems that this item does not drop on the first playthrough of the story mission. I didn’t try playing it again yet, but nevertheless this item not dropping on the first run is at least bothersome. So even if you get the right seed, you still can’t complete the new back piece.
I myself did make the Mysterious Vine before the patch, but as I said I asked around in LA for a bit, and nobody seemed to have this item. So I’m posting this here in hopes of confirment from other players and to bring this to the eyes of the officials.

EDIT: So I just replayed the Dragon’s Reach Part 2 Storyline with the same character with whom I had completed the story before. I did not get any of the items for the back piece again, except for the Chaos Orb, which I somehow received after the last conversation in Party Politics. The Pop-Up Mission Reward Interfaces did appear again, but they were simply empty.