This Nepenthes has been in a large indoor terrarium for about 9 months. I do not know what species it is. It has been fine until a month ago when its leaves started to turn blotchy red. Even the brand new leaves on my Nepenthes ventricosa are starting to turn black and crisp. It's been under fluorescent lights (T5 blue/red spectrum) and watered with only distilled water. It's planted in sphagnum moss, peat moss, perlite, and charcoal in proportions recommended by "The Savage Garden". I've attached a photo of one of the affected plants. Almost all of my Nepenthes have some level of red coloration on their leaves and some also turn black very quickly (about 15 plants). They are on a 12-hour photo period for the winter.
I live in Vancouver, WA. Do you know why the plants have developed altered coloration on their leaves and what should I do about it? Thanks!
Since all your plants seem to be having similar problems, it really seems like your soil is the culprit. Your soil media is probably breaking down making the mix anoxic. Like I mentioned before, it appears that they may have been too wet.
Repot all your plants into fresh media, but I'm going to recommend that you leave out the peat moss altogether. Just use long-fiber sphagnum with the other ingredients. Be sure to include the lava rock, vermiculite and orchid bark as recommended in the "Savage Garden" mix. If you omitted those, it will have made the mix less porous. Often it's necessary to adjust Nepenthes mixes to your own particular growing conditions. As I mentioned before, be sure you're not keeping them too wet.
While you have your plants out, inspect them carefully with a hand-lens. Look for any signs of insects such as scale or thrips. Scale insects will look like odd little bumps, or white crusting on stems. Thrips on very small long bugs that hang-out on undersides of leaves. Attacks from both often leave sticky residue on leaves. If you find some, you need to spray the plants. Here's a link to our insecticide podcast: http://www.youtube.com/watch?v=lbRCdJ8ZNF0
For more information on growing Nepenthes check-out our volume #3 DVD: http://cobraplant.com/index.php?main_page=product_info&cPath=38&products_id=257