Expert: Christopher Littrell - 12/11/2007

Question
QUESTION: I have a Nepenthes Sibuyensis and it is starting to turn black.  I also have a N. Sp1 from borneoexotics and it stopped growing.  I am growing them in a 18 x 18 x 18 exo terra glass terrarium. This is an inch of gravel for drainage and it drains well because I see the water level everytime I water.  Then I have a two and a half inch layer of a bark, perlite, and long-fibered sphagnum mix.  I am growing these two plants plus a Nepenthes Rajah which is actually grow fairly fast, but a little slow.  I cover the top screen with 90% of a towel.  Temperatures are up to 80 degrees fahrenheit and around 65 degrees lowest at night.  I also have an ultrasonic humidifier to increase humidity in the tank if needed.  The tank receives noon and afternoon sun each day.  Is there something wrong with this setup?

ANSWER: Hello Jake,

Are the Nepenthes blackening from the top down? Blackening leaves from top to bottom indicates root rot in Nepenthes, a particularly insidious problem when growing them in terrariums or with water trays full of standing water. You will likely need a greater depth to the soil as even Nepenthes roots will grow more than two inches long, placing them dangerously close to standing water in shallow soil.

An alternate route to use with Nepenthes is to pot the plants seperately and place them in a terrarium mostly for humidity purposes.

Noon sun is also a possible problem since terrariums refract light and build up heat. In addition, partial sun is what Nepenthes tend to get in nature. If the leaves are drying and burning, they might be experiencing leaf burn from intense noon sun. Try to keep the sun exposure down to morning and evening sun with indirect sun during the noon hours or add a slightly sheer screen in front of the terrarium to cut back on leaf burn.

Nepenthes will tend to slow down in growth after being shipped and replanted. They need a few weeks to adapt to new conditions and reestablish themselves.

Send me a followup to describe how the blackening is progressing. I hope it is not top down.

Christopher



---------- FOLLOW-UP ----------

QUESTION: actually it only receives afternoon sun, like around 2, and i can control the intensity of the light and the direction

ANSWER: Hello Jake,

O.K. that sounds good. Then the main thing would be to ensure that the Nepenthes are not succumbing to root rot in shallow soil mix. I would add at least another 2-4 inches to the soil or just use individual pots for the plants just in case.

Christopher

---------- FOLLOW-UP ----------

QUESTION: ok then, how deep should the soil in top of the drainage layer  be?  I use a lot of long-fibered sphagnum moss, isn't that airy?

Answer
Hello Jake,

The deeper the better as it will keep the Nepenthes roots away from the drainage layer. I would start with at least 5-6 inches depth of Nepenthes mix. Long fiber sphagnum is OK to use, but can absorb a huge amount of water. If your using perlite and orchid bark with the long fiber moss, and each ingredient is about 1/3 mixture, then it should be fine. Alternate mix would include 1/3 each of peat moss, which is granulated, dead sphagnum moss, orchid bark, and coconut fiber or alternatively two parts perlite to one part peat moss. Perlite, orchid bark, and coconut fiber all allow free passage of water without actually absorbing much, which is exactly what Nepenthes need.

Try to keep the drainage layer of pebbles from holding much water... just water a little at a time. That will reduce bacterial buildup and waterlogging. The deeper the soil is above the drainage layer the better. The trick is to keep the soil just moist, but not damp.

I hope your Nepenthes start growing normally soon,

Christopher