I've been having an issue with a few nepenthes, and I'm wondering if anyone has figured out the solution. They're growing fine up top, but they lose old leaves as quickly as they gain new ones. Over time this leads to a rosette with five or six leaves sitting on top of a tall woody stem. In my experience this can only happen for so long before the plant begins to suffer. Growth slows and new leaves start getting smaller, and if you're lucky you can start over by cutting off the rosette and rooting it, but at that point the plant is lacking energy and the cutting may fail.
I don't know what causes it. It's like the plant is abandoning its roots, but why? I suspected root rot, but I've found plenty of roots under some of the these plants. I suspected insufficient drops in night temperature, but my night drops are decent these days, and one of the plants suffering is an ampullaria which I've never known to need much of a night drop. I suspected a fungal infection but I've treated with systemics many times. I suspected insufficient light, but these plants are growing alongside dozens of healthy plants in the exact same conditions. I'm at a loss.
Any similar experiences? What has worked and what hasn't?
This has happened to my plant before, so I would like to know too. Could it be that the stem is just too long after a certain point, and it is difficult to get water up to the growing point?
Lack of food. They are withdrawing the old nutrients to support the new growth. Feed em, feed em, feed em.
I have grown the Neps on this table for the past 4 years and performing almost all watering/feeding. The plants themselves stay managable with pruning but are easily 20+ years old. I have tracked down every living person who ever had anything to do with these plants to try to guesstimate their age and they are probably older than 20 years. As you can see, they easily hold 20+ healthy, full green leaves at a time on every vine. Losing leaves is not normal for Nepenthes and usually when mine begin to lose foliage I know to liquid feed again. I shoot dilute food into the pots, flooding the media completely, and doing no damage whatsoever. Root feeding has also been recommended by D'Amato.
Pitcher size is completely normal and almost all leaves make pitchers.
Start with 1/4 tsp per gallon of any liquid feed. You can do 1/2 tsp per gallon once every two weeks. I have even gone up to 3 full teaspoons per gallon of water on a small tester Nepenthes with no ill effects--I concluded it was probably excessive and had no effect on growth at this point. So, between 1/2 tsp and 3 tsp you have a great deal of wiggle room. 1/4-1/2 tsp is a very low rate overall and will not cause burn if your plants are in otherwise optimal conditions.
Also, if it was root rot the decline would be much faster. Additionally, you would see some kind of wilting with the majority of root pathogens because they attack and kill the roots, leaving the plant with decreased ability to hydrate itself.
The plant should start showing symptoms of greening up and regrowth in 2 weeks at the earliest. Some nutrients move quickly and you can actually watch them progress through the leaves, but for a healthy appearance and new leaves you need to be patient. Once a week at 1/4 tsp for two weeks should give you a noticeable jump in vigor.
Let me know how it goes if you try this.
I tend not to feed plants through the roots to avoid accelerating substrate rot, but this does make sense. I shouldn't be waiting for pitchers before I feed as the plants without pitchers might be the ones needing food the most. I'll do some extra feeding and see what happens. Thank you.