Pinguicula moranensis

About this plant

Butterworts trap prey on the surface of their leaves. In the growing season Pinguicula moranensis makes a flat rosette of rounded leaves, each up to about 9 cm (3.5 in) long, so a large plant spans 15 to 20 cm (6 to 8 in), covered in tiny glands that produce a greasy, sticky film. Small flying insects stick, the leaf edge curls slightly, and digestive enzymes do the rest. Large pink to purple flowers on tall stalks appear through much of the year, in two flushes: a long one from the winter rosette that runs into spring, with each flower lasting several weeks, and a shorter one in late summer. The flowers cannot pollinate themselves, because the stigma sits as a flap over the anthers, and in the wild they are visited by hummingbirds; a windowsill plant sets no seed unless you hand-pollinate it, so unlike a Cape sundew it never sows itself around your other pots.

As the dry season approaches, the plant replaces its carnivorous leaves with a tight rosette of small, thick, non-sticky leaves and waits for rain. This seasonal change is the key to growing it well, and it also makes the plant unusually tolerant of neglect at the right time of year.

Light

Bright light with a few hours of direct sun suits it, and it copes with an ordinary bright windowsill better than almost any other carnivorous plant. Under strong light the leaves flush pink. It does not need, and in hot weather does better without, full afternoon sun: many wild plants grow on north-facing rock with little direct light, and the largest cultivated plants are often grown in dappled shade. A grow light for 12 to 14 hours works well indoors, but put it on a timer and shift the hours with the seasons; a slowly lengthening or shortening day is what cues the change between summer and winter leaves.

Water

In summer growth, keep the medium moist with mineral-poor water, using a shallow tray or watering from the top and letting the surface dry between waterings. When the small winter rosette forms, cut watering back sharply. Practice varies on how far: some growers let the tray dry out for about a week between waterings, others keep the pot mostly dry and moisten it only slightly and occasionally; forms with larger winter leaves tolerate slightly damper soil than those with tight, tiny rosettes. Err on the dry side; rot in winter is the usual way this plant is lost.

Growing medium

Unlike most carnivorous plants, Mexican butterworts often grow on limestone and tolerate neutral to slightly alkaline conditions. One good mix is equal parts peat, coarse sand and perlite with a little dolomitic lime stirred in; another is equal parts sand, perlite and pumice or lava rock with one part of peat and no lime. Both work, and the common thread is a mostly mineral, open mix with only a small proportion of peat, because pure peat holds too much water for the shallow roots. Shallow pots suit the shallow root system.

Temperature

Comfortable at ordinary room temperatures of about 15 to 30 °C (59 to 86 °F) in summer; as a montane plant it is happy with summer nights down to about 16 °C (60 °F). Cooler, drier winters suit it. A winter night minimum of about 8 °C (46 °F) is the usual recommendation. The plant is not frost hardy.

Dormancy

What this plant needs is a dry rest, not a cold one; the succulent phase is not a true dormancy. Watch the leaves: when the new leaves come up small, thick and without the sticky film, the plant has switched to winter mode. Reduce watering to almost nothing and keep it bright. When sticky leaves reappear in spring, resume normal watering. Under a fixed indoor light cycle the plant can stay in one leaf type for a long time, which is not dangerous in itself but means the two phases stop alternating; adjust the timer through the year so that day length rises and falls, and keep the plant drier whenever it is in its succulent form.

Feeding

The leaves catch fungus gnats, fruit flies and other tiny insects, which is why growers often place a butterwort among other houseplants as pest control. Feeding is optional. Opinions on fertiliser differ: some growers give Mexican butterworts a light fertilisation of the medium, while others hold that root-zone feeding can damage them and use only a very dilute foliar spray, kept off the flowers, which it spots. The cautious course for a windowsill plant is to let it catch gnats and, if you feed at all, to use a weak foliar spray.

Repotting

Repotting is needed only every two to five years, or sooner if a salt crust forms on the surface or old leaf thatch stops new roots reaching the medium. Either way, do it while the plant is in its winter rosette, when it can be lifted with almost no root disturbance. Propagation is easy from leaf pullings: detach a whole leaf with its base intact, lay it on moist medium, and a new plantlet forms at the base within weeks. Winter rosette leaves work especially well.

Common problems

Almost every loss comes from winter watering. Grey mould can follow in a dim, stagnant, humid winter; fix the conditions rather than spray, and avoid any fungicide on butterworts, cinnamon included. The fungus gnats the plant catches can also be a nuisance: their larvae live in wet medium and chew leaves that touch the surface, and a topdressing of coarse sand a few millimetres deep deters them. Plants sometimes push themselves up out of the pot on their flat summer leaves and sit for months with exposed roots; the fix is to snap off the older downturned leaves and press the roots back into the medium.

The second most common issue is a plant that is not what its label says: the Mexican Pinguicula hybridise readily and many plants sold as moranensis are hybrids. Care is the same, so this matters mainly for record keeping.

Species-specific notes

Pinguicula moranensis is highly variable across its range and botanists have treated some populations as separate species. A white-flowered form is sold as ‘Alba’, and many clones circulate under place names or letter codes without locality data. Many named hybrids, such as those with Pinguicula ehlersiae and Pinguicula gypsicola, are grown in the same way, though the crosses with P. gypsicola need an especially dry winter.