Question
QUESTION: The pitchers on my Nepenthes miranda turn brown after a few weeks. I have a very large plant in a conservatory, with humidity from 45-75%, and temperatures from 18 to 24 degrees centigrade. THe conservatory mainly has slipper orchids. The Nepenthes miranda is watered erery day with RO water, leaves are sprayed, and occasionally feed with half strength orchid fertilizer from McBean's [phrag and paph strength]. It has grown very fast, has frequent blooms -- large sprays of tiny florets, brown and yellow -- and is a climber, and I have organized a three-armed run for it down the centre and both sides of the conservatory. My question is: the pitchers are beautiful maroon and green stripes, maroon lips, but soon turn brown except for the bottom inch. Why? Should I cut the brown ;pitchers off? They look dead. The plant does a great job of catching flies, and my conservatory is insect-free, thanks to miranda. But I am worried about all these dead-appearing ;pitchers. I have tried to spray the new ;pitchers, thinking that perhaps the atmosphere was too dry, but they still turn brown. ?? Please help! Katherine in London.

ANSWER: Hello Katherine,

Each Nepenthes has its own life span for its pitchers. As long as the plant and its pitchers have good coloration, is constantly growing new pitchers and leaves, and does not appear to have pests or other problems, it is healthy. After opening, a pitcher will last anywhere from a few weeks to a couple months before turning brown from the lid down. The bottom section of pitcher will usually remain green and alive as that is where the liquid level is and where the nitrogen rich soup is. The top of the pitcher dies off and curls while the bottom section stays alive long enough to siphon off what nitrogen and other supplements the plant wants and needs from the insect soup left inside. My Nepenthes truncata does much the same thing. Several brown pitchers are hanging around for weeks while live maroon pitchers grow in their place. Every so often I do just go crazy with my shears and clip off as much dead growth as I can to thin out the overhanging dead stuff.

The only thing you might want to be cautious about is the fertilizer. Too much of a good thing can become a bad thing in the case of carnivorous plants. Most growers advise down to one quarter strength orchid fertilizer in a foliar feed, however; I have never fertilized mine and they do just fine. They can and will get all of their fertilizer from insects trapped in their pitchers. Too much fertilizer could burn their pitchers and leaves, so that might be a potential reason why the pitchers seem to die quickly. Other than that, the plant sounds quite healthy. A flowering Nepenthes is one that is "happy" where it is growing.

Christopher

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

QUESTION: Thanks Christopher. I realize that providing fertilizer to a carnivorous plant is not necessary.I was doing it because I was concerned that there were not enough insects in my conservatory to keep it going...but since it has been there I do not have any insects at all...so it is doing it's job. I will cut back on the fertilizer. A further question: It is still in the small hanging pot I bought it in, from the Royal Horticultural Gardens in Wisley, about 3 years ago. It is now more than 10 times its original size, has further shoots from the base and side shoots from the trunks, and must need re-potting. ? Is this an acidic soil,sphagnum moss, bark, etc? Do I repot on without disturbing the roots? Or do I clean the old compost away from the roots and repot in entirely new compost? I think, from the time it takes for the water to run through, that it is completely pot bound, and should be repotted. Is it just one size up pot, ie, does it like to feel snug in its pot like sn orchid? Please advise on all aspects of repotting my Nepenthes miranda. Thank you, Katherine from London I will send a picture next time.

Answer
Hello Katherine,

It is true that a Nepenthes does seem to need the nitrogen and phosphorous from capturing insects, but they can get by on very little. I have mine inside with no fertilizing whatsoever and they only receive an occasional insect once every few weeks.

It is a good idea to repot Nepenthes about once every year or two and to replace the old material with new. The soil will be, as you surmised, a mix of unfertilized, acidic sphagnum moss mixed with equal parts orchid bark and pumice or perlite. Mainly, the moss will provide the acidity and water retention while larger chunks of neutral materials provide drainage and air spaces. It would be best to use a larger pot as Nepenthes roots do enjoy being able to breathe and grow out a bit. Their roots do not grow out as much as other plants of similar size range, however; they still like plenty of room from my experience. Every time I have repotted my Nepenthes, they seem to have used what pot space I have given each time and seem to have settled for 8 inch pots for now. Both plants are relatively compact species with the N. sanguinea attaining 3-4 feet in vine length so far, and the N. truncata attaining about 15-18 inch diameter with pitcher size of one foot. The N. truncata root ball almost fills an 8 inch pot. I would advise going with one to two sizes larger each repotting until you see that the root mass has settled on a particular maximum size.

Most species of Nepenthes are tolerant of root disturbance with the notable exception of N. rajah. Simply clean some excess material from around the roots with your fingers and a little dip in some water. For large species of Nepenthes, it can be challenging to repot with all the vines and pitchers hanging all over the place. You may need help or at least some objects to brace the plant vines on while it is being repotted until you can get it settled. Keep the soil loose and airy, spongy to the feel. Nepenthes like air spaces and room to grow around their roots. Nepenthes roots are a little brittle and wiry. Excessive pressure can damage or break some off, however; a little damage will not phase the plant much and it will spring back into full growth in a week or two from a rough repotting.  Just try to be gentle and use the water dip to remove most of the material without much handling.

Christopher