Genshin Impact 2.0 introduces some local resources that are exclusive to the territories of Inazuma--Naku Weed is one of them, a flower that's necessary to refine weapons and for character's ascension.
Here's where you can find Naku Weed around Inazuma in Genshin Impact 2.0, and how you can use it.
Naku Weed on Narukami Island
On Narukami Island, players can find most of Naku Weed near the Grand Narukami Shrine. Most of them are found on floating lands and three of them in the shrine itself.
You can also find it on the Tsukumomono Groceries Shop in Inazuma City. You can buy up to 5 per 1000 Mora each. Note that the shop refreshes weekly.
Tatsurana: best location for Naku Weed
Tatsurana is the region where you can find the biggest quantity of Naku Weed. However this location is cover by a barrier.
The barrier is removed once you complete the quest: "Tatara Tales". To start this quest you need to talk to Toranosuke and Miyuki at the Kujou Encampment, west of the nearby Waypoint Teleporter.
Yashiori Island Naku Weed
Yashiori is the worst of the three islands available so far from Inazuma Region when it comes to Naku Weed. If you have not unlocked the entire Archon Quest, the island is struck by a heavy thunder storm.
The flowers are scattered near the Serpent Head and you can collect them when you travel to the area to defeat the boss Maguu Kenki. Keep in mind that Naku Weed in the wild will refresh every 48 hours.
Another simple way to get these flowers is to farm them yourself once you unlock the Seed Dispenser and gardening for the Serenitea Pot.
You can use the Seed Dispenser in a special gardening plot, the "Luxuriant Glebe Zone". Naku Weed takes 2 days and 22 hrs to grow, and you can plant a maximum of 8 pieces.