Remember, to unlock this boss you need to cut down the Erdtree with a herring but if you use the incantation "The Word" you can trigger a critical hit making it a cakewalk.
You should bring at least two shrubberies. The first shrubberies should look nice and not too expensive (They also like the ones with laurels in it).
The second batch of shruberries, you must place it here beside this shrubbery, only slightly higher so you get a two-level effect with a little path running down the middle.
Then cut down a tree with a Heering but of course "IT" can't be done.