Sorry to confuse the issue but having preached that all (or nearly all)
Mexican Pinguiculas should be kept dry throughout the winter dormancy, it
now looks as if a small degree of dampness is not only useful but in some
cases beneficial.
It seems as if many of the species that are flowering now (e.g. P.
rotundiflora, P. emarginata. P. acuminata etc,) can suffer from aborted
flowers either before they are fully developed or soon after opening, if a
small amount of moisture is not present.
I would not hesitate to keep those species that are not flowering now
completely dry. It's not so much that they neccesarily need to be kept bone
dry. It's just that it is a lot easier to get them through the winter this
way.
If you do wet your plants at this time of the year you need to be very
careful to avoid overwatering.This can be a problem using traditional soil
mixes. For some years now I have grown most of my Mexican Pinguiculas in
crushed tufa rock which has excellent water retention properties, tending
to hold large quanties of water while also restricting the amount of water
available to the plant. Overwatering is very difficult using this medium.
-- Phil