Mexican Pinguicula make excellent house plants and are among the easiest carnivorous plants to grow. In the wild, many Mexican Pinguicula grow in seasonal fog forests on limestone cliffs and tree trunks. Some grow in moss, others just cracks in the rocks, quite often on north facing cliffs. To understand more about the lives of Mexican Pinguicula please see the travelogues at World of Pinguicula.

Most of the Mexican species have heterophyllous leaves—the summer leaves are slimy and carnivorous; the winter leaves are succulent and not carnivorous. The plants like warm humid conditions when in the summer, carnivorous state. During the winter when they are in the succulent state they should be kept cooler and drier. Since these conditions are typical of those in a house they make great house plants in a bright sunny window. If you can grow African violets you can grow most Mexican Pinguicula.

There is some controversy over the best way to grow Mexican Pinguicula. Techniques that some growers swear by are death in other hands. Mexican Pinguicula are NOT bog plants and should not be grown like bog plants. Plants in the standard peat and sand "CP mix" may or may not do well depending on your exact conditions and which species or hybrid you have.

Most Mexican Pinguicula prefer an alkaline soil mix. I find a good mix for house plant Pings to be one part each of peat, coarse sand, and perlite. Dolomitic or limestone sand would be best if you can get it. This would counteract the acidity of the peat. I use silica sand blasting sand in the mix because that is what I can get. I then add dolomitic lime (a soil amendment found in garden shops) to the mix. I put in about 1 TBS of dolomitic lime to 1 or 2 cups of soil mix. That may seem like a lot but the plants do much better with it there.

There are other options on soil mixes that do work as well. You can use pumice in place of the perlite. Some growers may use vermiculite but it breaks down quickly getting slimy and requiring you to repot often. You can throw in some fine orchid bark but it will degrade in a year or two. Ground bark might actually be better and a good substitute for peat since it would be less acidic.

The main issue with soil mixes is matching the weight or water holding ability of the soil to the temperature and humidity where the plants are growing. Plants grown in humid greenhouses with misty or overhead watering need to be in a more loose soil mix. Plants grown in a typical house or classroom need a heaver, water absorbent mix. I never top water my plants and the pots are always sitting in a few cm of water. That is the reason I recommend a heaver mix than many growers at World of Pinguicula.

After planting the plants I then put a layer of silica sand on the surface of the soil up to 5 mm thick to discourage fungus gnats. Fungus gnat larvae like to eat Pinguicula leaves. I plant all my Pinguicula in 9 cm tall plastic pots and grow them using the classic tray method. When the plants have carnivorous leaves I use a water depth of up to 4 cm in the trays. When the plants are in the succulent phase I keep the water level lower but never dry. I have been growing a number of species and hybrids this way next to a window in my house for five years without repotting. Many of the hybrids bloom constantly. After about five years they need repotting because the deep thatch of old leaves get in the way of the new roots reaching the soil from the growing plants.

Most if not all Mexican Pinguicula can not self pollinate their flowers for physical reasons. The stigma forms a flap over the anthers. The outward facing part of the stigma is the part receptive to pollen. The inward facing non-receptive part covers the anthers keeping the pollen from getting to the receptive part of the stigma without mechanical assistance from a pollinator, usually a hummingbird.

Many Pinguicula clones in wide cultivation are partly or fully sterile. Inspection of the flower parts shows no pollen in some clones. It is not clear the reason for this however some become fertile if kept under cooler conditions.

Because of the way the flowers are constructed, it is tricky to pollinate them by hand. The easiest way to pollinate the flowers is with a tooth pick. You could play hummingbird tongue by poking the toothpick in and out of the flower trying to pick up the pollen from the anthers on the way out and deposit it on the stigma on the way in. However a more reliable way is to rip the flowers to get at the anthers and stigmas directly. To rip the flowers hold the top petals with one hand and the lower petals with the other and carefully tear off the lower petals. Do no touch the stem as you are likely to damage it. You can use a toothpick to transfer pollen the from the anthers to the stigma or use a forceps to remove the stamens and paint the stigma with the anthers. It may take some practice.

For good germination the seeds need temperatures between 15°C and 25°C (60°F to 80°F). To prepare a pot to start your seeds, fill it most of the way to the top with your favorite mix with the top cm being a sifted part of your mix so it is finer. Place the seed on the surface of the medium and don't bury it. The soil should be damp and not sopping wet. You may want to put the pot in a plastic bag if your environment is dry. You get better control germinating seeds under lights although in the shade of a greenhouse works. Seeds germinate in 4 to 8 weeks. Please see Sowing Seeds Step-by-Step for more details on starting seeds.

To maintain these species long term Mexican Pinguicula need seasonal light cues. With proper light cues most species will have carnivorous leaves from mid spring through fall. Winter through early spring they will have succulent, non-carnivorous leaves. Plants grown under continuous light period will essentially get stuck in the non-carnivorous phase. I would like to know if there is a Mexican species or hybrid that will live long term under continuous light period. I have not found one yet although I suspect the species that have carnivorous leaves year round like P. gigantea may work.

The seasonal changes are cued by light, not moisture. Water the plants according to the leaf type, not season. When the plants have carnivorous leaves they need to be kept moist and enjoy high humidity although they do just fine at 20% RH. When they have succulent leaves the plants need less water. Keep the soil lightly damp. Some species can be totally dry if the air is very humid. Chances are your conditions are not humid enough so don't let the plants dry out.

Mexican Pinguicula can be propagated by carefully removing succulent leaves.  The best time is just before new carnivorous leaves appear in the late winter or early spring. Please see Propagation -- Mexican Pinguicula Leaf Pullings for instructions. The transition time between succulent and carnivorous leaves is also the best time to repot Mexican Pinguicula.

-- John Brittnacher

For more information please see:

About Carnivorous Plants: Evolution -- the Lamiales Carnivores

Powell, Charles L. (1987) Mexican Pings. Carniv. Pl. Newslett. 16(4):106-110 ( )

Beckstrom, Marc (1979) A Search for Mexican Pinguiculas. Carniv. Pl. Newslett. 8(2):55-57 ( )

Lau, Alfred B. (1993) The discovery of a new Pinguicula from Ayautla, Oaxaca, Mexico. Carniv. Pl. Newslett. 22(1-2):26-27 ( )

Wix, Lloyd (1998) Pinguicula emarginata -- a variable and distinctive Mexican species. Carniv. Pl. Newslett. 27(4):121-123 ( )

Pinguicula 'Pirouette' is a complex hybrid: Pinguicula agnata x (moranensis x ehlersiae). Most Mexican Pinguicula species can be hybridized.