I have been growing Pinguicula for a couple of years now. I currently have around 20/25 species and hybrids and have been relatively happy with the results I have obtained. I recently had to change my grow area and so the plants are experiencing their first summer in their new grow area.
I have observed several pots of plants are displaying early browning of their summer leaves (largely P. agnata and P. moranensis forms). The leaves appear to brown and die, beginning where the leaves touch the media. It is certainly not regular plant growth, as last years winter leaves are still present on some plants and are in good condition. No pests are visible and so I consider the problem as a result of their new growing conditions.
The growing conditions are as follows:
Media: Inorganic, roughly 1:1:1Pumice, sand and vermiculite (all washed prior to use)
Watering: Tray watering, top of media dries between watering (tap water, but very low dissolved salt content)
Light: Artificial, they get heaps, so no worries here
Temps: Currently 20 to 35 degrees day and 10 to 20 degrees at night
Humidity: Typically 20 to 40%, but a little higher depending on atmospheric humidity
Feeding: Dried, crushed insects when I can be bothered (every couple of weeks or so)
Here is an example of the problem (P. agnata 'Romol'):
I certainly keep my plants on the dry side and the humidity is on the low side. Could the leaves be drying, starting where they touch the dry media? At first, as the problem begins where the leaves touch the media, I thought that may be the problem. But it is not happening in all my pots and only certain species and hybrids seem to show the problem.
Any ideas as to the cause would be most appreciated. Thanks in advance.