Folklore of St Johns Wort

This plant blooms during the summer solstice and is at its most powerful on the 24th of June, St Johns Day. On this day it is ceremonially burnt on bonfires in honour of the festival.It is  very powerful against faerie spells and will protect against demons, witches and evil spirits, hence its ancient name of Fuga Daemonum.
'St Johns Wort doth charm all the witches awayIf gathered at midnight on the saints holy dayAnd devils and witches have no power to harmThose that do gather the plant for a charmRub the lintels and the post with that red juicyflowerNo thunder no tempest will then have the powerTo hurt or hinder your house; and bindRound your neck a charm of similar kind'

The plant is imbued with magical powers and can be used for divination, but gathering the flowers can be difficult as the plant sometimes moves away from anybody trying to pick it.
It is also dangerous to step on, if you were careless enough to step on a flower during the day faeries would whisk you away on a wild ride across the countryside and then drop you in a ditch miles from anywhere. Stepping on a flower just before bedtime would ensure that you were kept awake all night by mischievous elves, but to ensure a good night's sleep, with no bad dreams, place a sprig of the plant with some thyme under your pillow.