Hardening off

Ok my n. x coccinea "red" and my the 3 ventratas i have in my tank are getting big (as expected!). Any tips on hardening them off? They get day temps of around 85 (sometimes close to 90) and night temps of about 75 (which is room temp, i raise the temp during the day up with the lights). So how would i go about this and how long should the hardening off period be?

Open the lid of your terrarium a little bit at a time, once a week, until it's open enough so that the tank humidity is the same outdoors. The new growth will start to adjust. Unfortunately, the existing growth will be affected, no matter how slowly you acclimatise, with pitchers loss and leaf wilting or blackening.