There aren't a lot of these that begin with the letter I, but there are some important ones. Get it, see what I did there with that i?
Indigo Weed - Protection
Also Called: Baptisia
Iris - Attracts wisdom, courage, and faith. Use fresh iris flower to purify an area. Represents a belief in happy reincarnation. Symbolizes faith, wisdom, and valor. Useful for consecrating ritual wands. Used in rituals designed for baby blessings.
Irish Moss - An excellent luck herb. Carry or place under rugs to increase luck and ensure steady flow of money; carry on trips for protection & safety; use to stuff luck or money poppets. Add to luck oil to increase its strength. An excellent gambler's herb. Sprinkle an infusion of the herb around a business to bring in customers.
Iron Weed - Carry in a purple flannel bag for control over others, including boss and co-workers
Ivy - Protection, healing, fertility, and love. Hang an ivy plant in front of the home to repel negative influence and discourage unwanted guests. Mix in a sachet with Holly as a wedding gift to provide protection to the newly married couple. Place ground ivy around the base of a yellow candle on a Tuesday, then burn the candle to discover who (if anyone) is working negative magick against you.