St. John’s wort is probably one of the most widely-recognized herbs because of its association as an antidepressant. Long before Prozac, people were using this to treat ‘melancholy.’ It has been used as a healing plant in many cultures throughout the milennia, and many people regarded it as having magical properties, able to dispel evil spirits.
While we may not consider it useful for protection from spirits any longer, it’s still a good herb to have around, and fortunately, should grow just about anywhere.