The weird thing though, wouldn't it make more sense to water the begonias with a spell of some kind? IDK how modern hoses are, but the most advanced technology you'll find at Hogwarts is the plumbing system, their kitchen, and the Hogwarts Express, anything more modern than that doesn't on campus. Even though cell phones existed in the 90's, it wasn't like today where everyone and their brother has a cell phone. But say the new generation had cell phones before they were old enough to attend Hogwarts, they wouldn't work if they brought them to Hogwarts. I'm probably just rambling at this point, but you'd the an herbology professor who is also a witch wouldn't need a hose to water the flowers.