Most people are concerned with ventilation only because it the high humidity fogs the glass, so they'll arrange a narrow open vent of some sort over the front glass and use something like a computer fan to blow across it. (There may be someone here with more information on this trick--I've never done it myself.) Otherwise, you do get enough for both frogs and plants to survive quite well, as PHflame points out. It's more visual aesthetics than a health issue.
-----
Patty
Pahsimeroi, Idaho

D. auratus blue, auratus Ancon Hill, galactonotus orange, galactonotus yellow, fantasticus, reticulatus, imitator, castaneoticus, azureus, pumilio Bastimentos. P. lugubris, vittatus, terribilis mint green, terribilis orange.