You need to visit the location with the Temple of Growth. Dryads and intelligent humanoid plants live there. After passing through the temple, you should enter it again at the level where you were introduced to the mechanics of blueberries, there will be a passage in the wall that was not available during the first passage. There will be a small test, at the end of which there will be a cutscene. After it, you will get the achievement you need.