Why is Hugo so focused on growing his own plants and building unique flavors in the novel, Under the Whispering Door?

Hugo uses his unique brand of tea to immerse the spirits in their memories and give them strength to move on. He uses them as a sort of mediator. A soothing concoction that encourages them to address their fears and speak what is on their heart. He is also able to create teas for the living and believes that it brings people together just as well as it helps lost souls. This is why Hugo focuses so much on growing his own plants and building unique flavors depending on who needs them. The tea is meant to make everyone feel cared for, accepted, and as a bigger part of a whole.