Q/A #117 - Pinguicula laueana Didn't Like the Hot Window

A tropical Pinguicula can sometimes decline even when other butterworts growing beside it remain perfectly healthy. Individual species may be less tolerant of heat and other environmental stresses than hybrids, so identical growing conditions do not always produce identical results.

Why Did One Pinguicula Die While the Others Were Healthy?

Question:

I purchased three different butterworts: Pinguicula laueana, ‘Aphrodite’, and P. gigantea × laueana. The ‘Aphrodite’ and P. gigantea × laueana are doing great, but the P. laueana recently died.

Shortly after I received it, the P. laueana began producing small, succulent leaves. It remained in that growth phase for several months, but eventually all of the small leaves dried up and the plant died.

All three butterworts received the same conditions: about five hours of direct sunlight followed by several more hours of bright indirect light. I watered from the top whenever the soil began to feel dry.

I grow them in Southern California, and the window can become extremely hot during summer—sometimes reaching the upper 90s to low 100s °F. Could the heat have killed the P. laueana?

Submitted June 2020.

Could Excessive Heat Have Killed the Pinguicula?

Response by Jeff Dallas:

Based on the conditions described, excessive heat was likely a contributing factor.

Tropical Pinguicula appreciate bright light, but some species can be more sensitive to high temperatures than hybrids. Pinguicula laueana is one of the species that can be somewhat less forgiving when conditions become excessively hot.

We have seen the same thing at the nursery. On one occasion, a pot containing a Pinguicula species overheated in strong sunlight and the plants died, while hybrid butterworts growing immediately beside them remained healthy.

That difference is important. Two Pinguicula growing in exactly the same location may not respond the same way. Hybrids are often more adaptable, while individual species may have narrower tolerances for temperature, moisture, or other environmental conditions.

Was the Small Succulent Growth Normal?

Yes. The production of small, succulent leaves was not by itself a sign that the P. laueana was unhealthy.

Many Mexican Pinguicula naturally change from broad, sticky carnivorous leaves to a smaller rosette of succulent leaves as part of their seasonal growth cycle. Some will remain in this form for several months, and many can even flower while producing succulent growth.

The important distinction is what happens to the center of the plant. A healthy rosette of firm new leaves usually indicates normal seasonal growth. Progressive drying, browning, or deterioration of the entire rosette indicates that the plant is under stress.

How Can I Prevent Heat Stress in Tropical Pinguicula?

Give tropical Pinguicula plenty of light while avoiding locations that become excessively hot. Morning sunlight followed by bright or dappled light during the rest of the day works well for most varieties.

Pay particular attention to windows during summer. Direct sunlight passing through glass can create much hotter conditions around the plant than the temperature elsewhere in the room.

If a window becomes extremely hot, move the plant farther from the glass, provide some protection from afternoon sun, or grow it under LED lights where light intensity and temperature are easier to control.

Related: See our tropical Pinguicula care guide for complete instructions on lighting, watering, soil, seasonal growth, and troubleshooting.

The original question and response have been edited and expanded for clarity.