Pinguicula seem to be the latest craze in the carnivore world. I mean, to be fair, they are compact, colorful, variable, easy to grow, and propagate well. Native to the forests of Mexico and Central America, these sticky carnivores are often found growing not in peaty bogs like their less impressive (sorry!) US counterparts, but up on trees, rock faces, and mosses. While most literature suggests using a peat based mixed but with higher proportions of perlite or sand, many growers have turned to using completely inorganic mixes for their Pinguciula, namely various mixes of lava rock, perlite, sand, crushed coral, turface, vermiculite, akadama/kanuma. I've even seen kitty litter being used, showing the tolerance of these plants and the lengths people will go to not use normal potting materials. I thought I'd give it a try, as reportedly these mixes last virtually forever, reduce the risk of rot and the dreaded browning heart disease, as well as providing the slightly alkaline conditions these plants prefer. My new inorganic mix consist of equal ratios of perlite, vermiculite, and crushed coral.
Perlite is a white, soft rock that is mostly consisted of silicon dioxide and aluminum dioxide. It's slightly basic on the pH scale. lightweight, high permeability, and retains a small amount of moisture. This all combines into a material that is perfect for Pinguicula, by keeping the media well aerated and preventing stagnant air and water. Just be careful not to breathe in the dust.
This component is somewhat controversial in that different growers either seem to love it or hate it. Vermiculite is the mineral mica that has been superheated until it expands. It has much of the same properties as perlite stated above, but holds quite a bit more water. I use it as an inorganic replacement for peat that holds slightly less water. The issue stems from the fact that when vermiculite is kept constantly wet, it tends to break down into mush that compacts and is no better than pure peat. I've avoided this issue by not letting my plants stand in water. I still use vermiculite rather than not, as I tend to underwater my Pinguicula and the little bit of moisture is lifesaving.
Crushed Coral (Aragonite)
This additive is a relatively new development in the Pinguicula growing world. Crushed coral is often sold to fish hobbyists as a substrate for their tanks, acting as a pH buffer and adding calcium to the water. Since many Pinguicula are found on limestone cliffs, this increase in pH and calcium is welcome by many plants. I picked up a 10 pound bag of this stuff at my local pet store, and the consistency is like that of coarse sand. It doesn't seem to hold water particularly well, and I imagine it plays the same role as coarse silica sand. However, Pinguicula seem to appreciate the slightly alkaline pH of the media, especially if you're using peat.
Other Media Additives
Turface seems to be a very popular media for Pinguicula, given it's neutral pH, ability to absorb water, and it's coarse nature. This is one addiitive I plan to try out soon, especially given it's cheap price and some species' need for a coarse, well draining mix (looking at you, immaculata).
Akadama/Kanuma is a popular heated clay rock that's used for bonsai. Recently, growers have been using it for the likes of Heliamphora, Drosera, and ultramafic Nepenthes. (N. pervelii seems to prefer this media over traditional sphagnum). It has much of the same properties as turface and perlite, as well as being exceptionally high in quality and price. It's also slightly acidic, so due to that fact and the price tag, I'll stick to using this on Nepenthes.
Lava Rock and Pumice are two closely related rock additives that offer the same benefits of perlite or turface. It can be hard to fine grain sizes small enough to use for Pings, as garden centers usually sell them in the sizes of large grapes. However, these larger rocks are perfect for mounting pings onto them, and creating a breathtaking display. The only species I have mounted is my ugly, no good P. laxifolia, which only grows hanging off of rock faces in the wild.
I'll update the progress of these newly potted plants in the future, and if all looks good, I'll be transitioning almost all of the pings into inorganic. However, it's important to note that several species, namely P. gigantea/Alfred Lau 13 and P. emarginata grow relatively damp, and may appreciate the addition of peat or vermiculite. Species like P. mesophytica (which if anyone has, please snendn) prefer a mossy mix with sphagnum. Stay tuned for more blog posts, and until next time!