Mexican Pinguicula change leaf forms, they do not have a dormancy. Seasonal triggers for leaf form changes vary among the different species.
I have always kept, all of my Pinguicula, Mexican species and hybrids included in trays of water --- year-round. As for DORMANCY, very few Mexican Pinguicula, if any, actually have a true DORMANCY. Most of them just have what is called a heterophyllous growth pattern. They change the type of leaves they make depending on the season. Just because they are growing more and smaller leaves does not constitute a dormancy.
One piece of information I believe is critical to success with keeping them moist/wet is to ensure they have a 15-17 hour photoperiod and very strong light, without overheating their leaves (this is most easily possible using fluorescent lighting). I use many 4 foot fluorescent lights and place them withing 2-4 inches of the plants and use timers to give the plants a 15 hour photoperiod.
Despite this treatment, some of the Mexican plants change their leaf form in an apparent random manner (large groups of the same clone will not all change leaf form at the same time).
Sometimes it is possible to bump a plant out of Winter-form leaf and get it growing Summer-form leaves by ensuring all conditions are most Summer-like. Warm temps 80-90F, moist, 11 hour or more period of light, plenty of food (I use a light sprinkling of dried insect powder).
