Go to Qufim Island and follow a path down the cliff to (F-8). Be warned that a Kraken may spawn right on top of the flowers. If you are a low level, keep a safe distance until 21:32. Any time between 21:32 and dawn, use sneak to approach safely and click on the Night Flowers for a cutscene.
If attempting this quest at lower levels, it is beneficial to reach the path before 20:00 to avoid the Banshees that appear once night falls. A Goblin Bounty Hunter also runs down the path that leads to the Night Flowers and the Kraken, so be extra careful.