There is a substance in every tea called »theine«. It works as a natural fertiliser for plants.
»monstea«, a tea for children, provides this information in a playful way.
After consuming all the tea the monsters could be used as a flowerpot for plants.
One teabag is labelled as »Zaubertee« (magic tea) which is supposed to be used
as a fertiliser for the seeds you're going to grow.