One of my favorite magical herbs to use in romance spells is patchouli. In magic, patchouli corresponds with wealth, love and sexual attraction. Long associated with hippies and counter culture activists, this earthy scent has long been considered an aphrodisiac. Parts used are leaves and essential oil.
In the garden, patchouli is a bit of a needy herb (in my experience). It is a perennial which (if happy) grows to up to three feet high. Down here in the coastal South, patchouli likes morning sun and afternoon shade and needs to be watered fairly often in the summer. Farther north, it needs to be protected from freezing or replanted every year.