Speak to Wuoshi at -599, 379, 623 on Aeterna Gardens within the Vesspyr Isles to begin this quest.
Walk into the pond next to Wuoshi to gather some water.
Head to the smaller isle of Aeterna around -507, 332, 187 . The third batch is at the bottom at -536.44, 260.42, 172.18 on the lower level.
There are several groups of flowers on this isle to water. Each group has four flowers. You'll have to return to the pond to get more water after every four flowers; do this until you water 12 total.