Mexican butterwort leaf pullings: timing, removal and rooting

Why pullings are the standard method

The ICPS calls leaf pullings the easiest way to propagate Mexican butterworts ^[1], and its growing guide sends readers to them as the best method ^[2]. A detached leaf produces new plantlets that are genetically identical to the parent. That matters for hybrids such as P. ‘Pirouette’, a complex cross involving P. agnata, P. moranensis and P. ehlersiae ^[2]. Seed is the other route, but most Mexican species cannot pollinate themselves because a flap of the stigma covers the anthers, so seed has to be made by hand ^[2].

The pullings page notes there is no single best method for all of the many Mexican species, but that the same general principles work for most of them with minor changes ^[1].

Summer leaves, winter leaves and timing

Most Mexican butterworts grow two kinds of leaves. Summer leaves are sticky and carnivorous, thin in some species and succulent in others. Winter leaves are succulent, dry and non-carnivorous. A few species keep carnivorous leaves all year, smaller in winter ^[1]. The ICPS finds winter leaves taken late in the season work best for every species, although pullings can succeed at any time; how well they do depends on how thick the leaves are and on the method ^[1].

The best moment, according to the pullings page, is spring, just before or as the first carnivorous leaves start to appear. For greenhouse plants, or plants otherwise on a natural light cycle, in the temperate northern hemisphere that means late March and early April. Leaves taken at other times may be slower to sprout, or so thin that they rot ^[1]. The growing guide likewise treats the succulent winter phase as the best time to propagate and repot ^[2].

Your plants only make winter leaves if they get seasonal cues. The ICPS guide says heterophyllous species need day lengths that slowly lengthen and shorten, from a greenhouse, a sunny window or lights on a seasonally adjusting timer, and that under an unchanging light period they get stuck in one phase ^[2]. P. gigantea is an exception: it makes no succulent winter leaves and can be propagated at any time of year ^[2]. The light guide covers timers and day length.

Taking leaves without wrecking the plant

Butterworts have little in the way of roots and stems, so a rough hand can pull the whole rosette apart ^[1]. The ICPS adjusts the method to the type of plant.

Season matters for the parent too. P. gigantea can fall apart if it is repotted in summer to harvest leaves, while P. ehlersiae can fall apart if repotted in winter ^[1]. The Pinguicula moranensis profile describes that species’ seasonal cycle.

Method 1: on a damp mineral mix

1. Fill a tray or pot with a damp 1:2 mix of vermiculite and perlite ^[1].
2. Lay the leaves on the surface ^[1].
3. Decide whether to cover them. Depending on your humidity, and on whether you mist them now and then, they may or may not need a cover ^[1].

A variation uses your usual butterwort potting mix in small, clear, lidded containers. Start with the soil damp and lay the leaves on top. Evaporation fogs up the container, giving 100% humidity while the leaves stay dry, and the soil slowly dries out. Add a little water if the leaves start to shrivel. Once plantlets have sprouted, plant them into the soil and raise its moisture ^[1].

Method 2: a zip bag

This works best for large, fleshy leaves, such as those of P. gigantea ^[1].

1. Put clean leaves into a zip-lock bag ^[1].
2. Close the bag fully if the leaves are fairly dry. If they are wet, clip the opening so it stays partly open ^[1].
3. Optionally add a piece of blue paper shop towel to absorb excess water and steady the moisture. The ICPS author reports fewer mold problems with these than with white kitchen towels ^[1].
4. Check often. If a leaf starts to rot, open the bag further, and with a large mass of leaves consider removing part of the bigger ones. If the leaves shrivel, spray in some water and close the bag ^[1].

If your growing area is humid enough, leaves can simply sit in a dry dish, moving to a bag or terrarium, or getting a light spray, if they begin to shrivel ^[1]. The ICPS photos show P. moranensis pullings taken from carnivorous summer leaves sprouting in a zip bag after two months ^[1].

Light, rot and what not to add

The leaves do not need strong light, but they must stay out of direct sun so they do not cook ^[1]. Leave out additives. The ICPS author once compared P. ehlersiae leaves treated with rooting hormone, vitamin B1 or both: the treated leaves rooted quickly, but the untreated ones produced more and larger plantlets ^[1]. Fungicides are ruled out altogether: the growing guide warns never to use any fungicide on any Pinguicula, even in the soil, and that includes cinnamon ^[2]. Rot is handled instead by giving the leaves more air and less leaf mass per bag, as described above ^[1].

Potting up and growing on

Small plants take 1 to 2 months to appear. Plant them once the mother leaf has broken down and roots are visible ^[1]. No success rate is published.

The two ICPS pages suggest different mixes, both meant for indoor conditions:

• The pullings page uses pH-balanced potting soil containing worm castings, with 2 or 3 parts perlite added per part of soil depending on the brand, or equal parts perlite, sand and peat with some calcium carbonate sand or dolomitic lime. It notes that many growers use an all-mineral mix ^[1].
• The growing guide uses equal parts peat, coarse sand and perlite, with about a tablespoon of dolomitic lime per cup of mix to offset the peat’s acidity, topped with up to 5 mm of coarse silica sand to discourage fungus gnats ^[2].

Either way, these are not bog plants. The guide keeps pots in up to 2 cm of water while the leaves are carnivorous and lets the tray dry for a week or so between waterings in the succulent phase ^[2]. See water and fungus gnats.

Unlike most carnivorous plants, these butterworts respond to light soil fertilization, which the pullings page says can make them grow almost explosively. It prefers that to fertilizer sprays, which can collect in the crown and kill the plant, and shows over-fertilized plants with burned, leathery leaves; it urges extra caution with small plants ^[1]. The feeding guide explains the risks for other genera. With some experimenting, the ICPS expects mature plants in a year to 18 months ^[1].

Other butterworts

The method is specific to the Mexican group. Warm temperate species such as P. primuliflora keep the same type of leaf all year and are short-lived perennials; the ICPS advises hand-pollinating them and saving seed to keep them going ^[3]. Cold temperate species such as P. grandiflora form winter buds, and the ICPS shows P. grandiflora buds with gemmae clustered at the base; seedlings of this group are separated after their first winter ^[4]. For seed of either group, see sowing seeds.