Professor Pomona Sprout
Reasoning: The card of a patient, tolerant and wise person, one who often has natural skills at healing and nurturing growth in others and promoting teamwork.
Professor Sprout is head of hardworking and (usually) cooperative and friendly Hufflepuff house. She seems good-natured and hopefully nurtures learning in her students as well as she nurtured growth in her plant charges.
In a traditional tarot deck, this is the King of Cups.
Notes
This sketch went fairly smoothly, except that I was unsure about how to do the interior walls of a greenhouse and I was afraid Professor Sprout would end up looking too much like Mrs. Weasley.... because while I don't really see them in my head as looking similar, they sort of end up that way on paper. *shrug*
The plants were fun... I wish I had room for more, but it was getting kind of busy in there already.