Various botanicals are said to discourage the presence of ghosts, especially rue and garlic. Here is a list of more botanical ghost busters and how to use them:
A strong scent of real carnations discourages and pacifies ghosts. Synthetic scents will not have the same effect. The best method is to strategically place bouquets of carnations replacing them as their aroma fades.
Hawthorn repels evil ghosts, while permitting the entry of helpful souls. Maintain a barrier of living hawthorn bushes and trees outside the home or bring branches within; the catch to the latter plan being that hawthorn is among the plants most associated with Fairies. Do not break off a branch without first seeking permission from Fairies, lest ghosts become the least of your problems. Branches found already fallen may be considered a gift and safely retrieved.
Boneset guides ghosts elsewhere, attracting protective, benevolent spirits instead. Boneset may also be used to protect people and animals from "ghost sickness," the illness that some believe may emerge after extended contact with the dead. The most potent boneset is found growing on or near graves. Supplement it with white pine for added enhancement.
Hang fresh boneset branches over doorways, or burn young boneset branches and twigs within a cauldron to drive away existing ghosts.
To prevent hauntings, surround your home with living bean plants. Not only do beans repel ghosts but allegedly, the plants sing to wandering ghosts, guiding them to the next realm. If you'd like to hear these songs, a shamanic art, sit under the vines while they're in bloom. Meditate or allow yourself to fall asleep.
Burn dried powdered bistort to banish ghosts, wafting the fragrance as needed.
Fennel can be used to ghost-proof individual rooms or an entire building. It only works on some ghosts but may be worth trying. Stuff keyholes full of fennel to prevent ghosts from entering the room. It also stops them from leaving, so if the ghost is already in the room, it may be trapped.
According to Hildegard of Bingen, ghosts hate pine trees and avoid places where they grow. If it's not possible to surround your home with living pines, bring small living trees within it and situate them strategically.
Tiger lilies planted near doors and windows allegedly prevents the entry of ghosts.
If a ghost has taken up residence in your home or within another building, hanging alyssum up in every corner of a house will exorcise it.
A wreath of fresh bay laurel leaves posted on your entrance doors signals "No Tresspassing" to ghosts. To provide relief from destructive and mischievous ghosts and poltergeitst, maintain fresh bay laurel branches and /or leaves within the home. Replace them as their green color fades.
Fumigating an area with camphor and mint is used to send unwanted ghosts in search of new housing. One application may not be sufficient, however. Use repetitions of mystical numbers for reinforcement. Repeat for three, seven, nine, eighteen, twenty-one, or twenty-seven days as needed.
Sprinkle a strong infusion of bayberry inside and around the perimeter of a house to exorcise existing ghosts and repel new ones.
Make a decoction of angelica roots or pour boiling water over the dried, powdered root to make an infusion. Sprinkling this within and around the home is an Iroquois recommendation for exorcising and preventing ghosts.
From: The Element Encyclopedia of 5000 Spells