Once people believed certain plants could tame or deter beasts. According to Gerard, loosestrife was used to pacify oxen by putting it on their yokes. In medieval times, people planted sage to ward off toads.
Earlier, Europeans had real concerns about their security. They believed in all sorts of ill-willed beings-ranging from witches and sorcerers to elves, flying demons, goblins, monsters, sprites, vampires, and other creatures of the dark. People used herbs as a means of protection.
Often the herbs had to be collected at a specific time or prepared in a particular way. For example, St. John's wort was harvested on a Friday in the hour of Jupiter during the full moon.
To protect their houses, people took special measures on Midsummer's Eve (June 23rd). The appropriate herbs for this occasion were bay, chives, fennel, golden ragwort, lousewort, St. John's wort, and yarrow.
Pieces of the plants were hung on the doors or over the doorframes. Sometimes they were formed into wreaths, or tied into a bag for hanging on entryways.
The custom of protecting doors is an ancient one dating from the time of the Chaldeans. In their book of magic, there was an incantation for this situation, quoted below from "Green Enchantment-The Magic and History of Herbs and Garden Making" by Rosetta E. Clarkson (Collier Books) in 1939:
"Flea-bane on the lintel of the door I have hung St. John's wort, caper, and wheat ears."
The Europeans may have used different plants, but the basic idea was still the same. People feared witches and sorcerers in particular, and used plants to prevent such individuals from entering properties. This was done by planting elder, hazel, holly, juniper, mountain ash, or yew in the yard. Yellow-flowering plants were an alternative.
Witches could be deterred if you placed a broom made from the broom over the threshold. On Midsummer's Eve they hung fennel from the rafters. Other plants used against witches were alyssum, cinquefoil, elder, hawthorn, hyssop, plum branches, rosemary, squill, and valerian.
Assuming witches had already entered the home, they used Christmas rose or rue to cast them out. For this purpose, they either burned the plants, or scattered them around on the floor.
