I don't feel qualified to vote because as a novice I don't know what the ideal humidity should be. But I choose 65% - 75% because that's what I have here in the spring/summer/fall months growing outside (northwest FL), though much of the summer is above that. In the winter, with the exception of very cold weather (20F), I grow in the garage (big south window) where the humidity stays 60-75. When temps get in the 20s outdoors, I bring my 70 plants into the Florida room(north facing 14 x 14, big windows, skylight). There the humidity stays above 50% even when the outside humidity is very low. I finally figured out that was thanks to the 20 gallon aquarium in the room! The aquarium does a better job than a humidifier, plus we get to enjoy the fish too.

Tami