If it's just a routine disinfecting, I would boild the fake plants in dechlorinated water for 15 minutes (don't know if that's overkill but it's what I do lol. Then again I'm also that weirdo that steams the entire cage once a week) without the frogs inside of course.
If there was a sick or parasite-infected frog or if a frog recently died of an illness I would actually throw them away and get new ones