Expert: Sarracenia Northwest - 9/3/2011

Question
Hello Sarracenia Northwest. I have this nepenthes ventrata and it's begun to grow smaller leaves and pitchers. This also occured last summer but i cut the growing point and let basal shoots grow out. But now these new two plants have gone from 6-inch leaves too 3 inch leaves and going smaller. A N. ventricosa on the same windowsill had this occur bet after a while grew back out to normal leaf size. There is also a N. Spathulata which died off after this phenomenon but had two basal shoots appear a week later. What is the source of the problem and how could I fix this so my plants can reach full size? They're in an east facing window which reveives ~5hours of morning sun and ambient light for the rest of the day. There's no fertilization and the only insects are  a small ant colony in the N. Ventricosa pot.

Answer
There are numerous reasons why plants produce shorter leaves.  Very bright light and lower humidity are the most common factors that causes shorter growth habits on plants.  This is completely normal, and since we're still in the summer season, I'd say that these factors are the most likely cause.  Bright sunlight makes plants more efficient with photosynthesis, so they don't need large leaves.  Plants also produce small leaves when humidity gets low as a way to reduce moisture loss.

As you've noted previously, the plants will resume larger leaves when the weather becomes more mild, such as in fall and winter.

The basal shoots and main stalk dying off is a common phenomenon for large fluctuating growing conditions.  Plants like very stable conditions, but they experience very large seasonal changes, they tend to change their growth habits to adapt.  Think of plants in the United States.  They too undergo very extreme growth changes to adapt to the extreme seasonal changes.  Tropical plants need to do the same, though they're tolerant to seasonal changes up to a point.

Unless you're willing to invest in a climate controlled greenhouse, the most you can do is simply allow these changes to happen.  I also recommend repotting your plants to remove the ant colony.  I just don't know to what extent the ants have a role in this, and I don't have any experience with ants.  I also recommend a weak solution of fertilizer, 1/4 teaspoon per gallon, applied to the soil weakly.  Make sure to flush the soil completely in between applications.  This may help prevent the main stalk from dying back every year.

Good growing!
Jacob Farin