So apparently I have had these in this shell for around 8 years. I'm surprised how resilient mexi pings are! These have been through severe under watering, low light, high light, and some neglect.
Original post, Pinguicula in a Quahaug shell 1 year
I find mex pings to very hardy, in respect to substrate, I've used everything from complex all mineral mixes to house plant soil and perlite, think as long as it's moist and airy it will be fine. Your pings look real good by the way! Which species/hybrid is it?
Cheers for sharing