My Nepenthes Ventricosa had been doing fine for several months - it ate really well outdoors in the summer and seemed to adapt reasonably well to the move into greenhouse for winter. It gets bright but not direct light and is kept moist and sprayed with rain water to increase the humidity. (Haven't checked the pH....)

But as of late, the pitchers are turning brown and shriveling just above the 'waist' on each. They still hold water, though. The plant seems healthy enough, with lots of new, vegetative growth on top.

Suggestions?