i'm sure this has been said before...many times;
it's not what you're putting in, it's the length of time it's left in the jar (and the more sugars in it, the bigger the chance for mold). there should never be any need to rehydrate flowers longer than an hour or so...then remove it. if kept sealed in a fruit/mason jar and refridgerated it won't get any dryer than when it was 1st put in. if just tossed back into a baggie you're wasting time...and fruit.