I don't use herbs for purification, but I clean the energies of the house like I do with my aura. Additionally, sometimes I also do banishment of unwanted energies with the Sanskrit mantra VINASA.
If you want to use herbs, here's a list of herbs fetched from the JoS4adults group and titled "Herbs and their Magickal Properties": alkanet, anise, arabic gum, asafoetida, avens, bay (Sun), benzoin (Mercury, Venus, Mars), betony wood, birch, bloodroot, broom, cedar (Jupiter), chamomile (Venus), coconut, copal, euphorbia, fennel, horseradish, hyssop, iris, lavender (Mercury), lemon (Jupiter), lemon verbena, mimosa, parsley, peppermint, pepper tree, rosemary, sagebrush, shallot, holy thistle, thyme, tobacco (Mars), turmeric, valerian, vervain, yucca.
Sage is ruled by both Mercury and Saturn. Sage is listed in that same book for this purposes: immortality, longevity, wisdom, protection, wishes. It also appears on a page from the JoS website. Read below
Sage:
Drunk as a tea, it is a relaxant for psychic work and at the same time heightens the senses and concentration. It can also be burnt as incense and the oil can be used as a rub for the same purposes. Infuse with quintessence and the element of water.
Herbs have little power on their own and must charged with the corrisponding elemental energy. You can fin more in the resources below. Read them all.
Resources:
(VINASA and SANANDA)
Banishing Ritual Magickal Uses for Herbs Important Information About Herbs
Yahoo! Groups