My success and appreciation of leaf-pulling as a propagation method for Mexican and other tropical Pinguicula species and their hybrids has gradually improved as I spend more time and gain more experience working with the technique and modifying my methods to discover nuances to its implementation.
I have discovered that my favorite way to implement leaf-pulling propagation, also has the secondary benefit of creating a, sort-of, short-term bank of small propagules. Many of these small plantlets, in my impromptu test, had survived well beyond twelve months, some more than twenty-four months, just waiting for suitable habitat insertion for them to become established plants.
Here is a photo, illustrating a group of plantlets, formed on leaf-pullings from Pinguicula agnata plants -->
The leaves were pulled in May 2007, and these plantlets had formed by June 2007, this photo was taken in November 2007, almost six months later. These leaf-pullings were generated by folding several layers of paper towels and placing them, as a liner, into clear clam-shell containers, recycled from ones used to market certain produce. They have vent holes in their tops and bottom sections.
[Instead of the method mentioned above, leaf-pulling propagation works equally well by just dropping the severed leaves into small plastic or styrofoam cups, with the added benefit of being able to write their names directly onto the cups, then discarding the cups, or reusing them after the plantlets are planted-up. Good lighting helps (as long as it doesn't over heat them), cool temperatures and moderate humidity are good, but moisture will quickly destroy leaf-pullings.]
The majority of these plantlets persisted until near December 2008, more than a year beyond the date this photo was taken. It is amazing how rapidly these plantlets establish and grow to adult blooming size. It can happen in just a few months, when these plantlets are planted in suitable conditions.
Leaf-pulling can also provide a batch of plantlets, waiting and ready to use to replace those that are lost to pests and disease, or to provide material for trades. Happy growing.