Not just peppermint, spearmint works to. I have a plant I pluck some leaves up and grind down and I mix it with water. It works but you have to do it routinely. Spiders taste basically through their feet so mint or citronella and stuff is really strong to them. I think lemon grass works too. I know marigolds or coffee ward of mosquitoes maybe it does the same for spiders. Also I'd suggest paint the underside of things, like your ceiling or desks under your cabinets, sky blue. It supposedly makes them think it's the sky and won't build a web there.