Q/A #34 - Nepenthes albomarginata Not Pitchering

QUESTION:
I received my Nepenthes albomarginata, Black in mid February, and since then it's grown one vine about a foot long. In that time, it's never made any pitchers, but now it looks like it's going to flower. I'm excited to see the flowers it makes, and if it's male or female, but I'm worried the plant might be weakened because of this, and the fact that it has not made any pitchers like my two other Nepenthes growing beside it. Should I cut the flower stalk off in this situation or let it grow?

The plant on the left is N. ventricosa x spectibilis I got from you guys last July. The one on the right is a N. sibyuanesis x talengensis. N. ventricosa is now over 3 foot tall on it's one vine.

They all get lots of indirect sunlight from the South facing skylight and windows, plus I keep five 36 Watt LED grow lights as supplemental lighting for 12 to 16 hours a day. Light meter readings show the N. ventricosa hybrid getting 3,000 to 4,000 lux at the leaf top area. N. sibuyanesis hybrid getting 4,000 to 5,000 lux at leaf tops, and N. albomarginata in center getting 5,000 to 8,000 lux at the leaf tops.

Before they were moved to this room just a week ago they were solely under LED grow lights because of the lack of good windows in room they were in since purchase. Light was kept about 6,000 to 8,000 lux on the leaf tops in general, with the N. ventricosa sometimes getting up to 15,000 to 25,000 lux on certain leaf tops until it outgrew the area the lights were able to cover and so things were moved to the brighter room when it became available.

I hope I'm doing okay with them, just surprised I was not able to get the N. albomarginata to pitcher in 5 months now. Humidity is usually over 50 percent and up to 70 percent overnight (The windows and skylight let in the cooler night air to drop temperatures from the 80's to low 90's during the day to about 70 degrees by morning or lower) Temperatures never get below 67 degrees at night with these plants year round.

Attached is a photo of the setup, with close up of N. albomarginata's possible flower stalk forming. Not sure, but it looks interesting.

Any advice you could share for keeping these plants happy would be appreciated, I love growing these plants and being able to keep them in a special room that's bright and also relaxing. I just hope it's bright enough to keep them all thriving.
(Submitted in July 2020.)

N. albomarginata, Black

Flower bud of N. albomarginata, Black

N. sibuyanensis x talangensis

The Collection

N. ventricosa x spectabilis

RESPONSE BY JEFF DALLAS:
This dark form of N. albomarginata can be slow to pitcher. It's definitely one of the Nepenthes that lives up to the stereotype of liking it warm and bright. Your conditions sound pretty good, but it may just need more sun. Ideally, it should get several hours of DIRECT sunlight. The color on your plant is dark, but it definitely could be darker to the point where you don't see any green. This is one of the few Nepenthes that can tolerate full sun.

One winter many years ago, I grew this species in my home in a west-facing window as an experiment. It got lots of direct sunlight when the sun was out, and it produced pitchers like crazy. I moved the plant back to the greenhouse the following summer, and it stopped producing pitchers. It grew long vines and flowers, but no pitchers until we changed the greenhouse film that allowed more intense sunlight. Some Nepenthes just won't pitcher unless they are getting enough intensity. N. albomarginata is one of them. They grow long vines in the wild to grow over tree branches and reach more sunlight. You mentioned that your plants get lots of indirect sunlight, so this might be the reason for no pitchers. 

(Keep in mind that what you think is bright enough is irrelevant. Nepenthes don't care what you think. Each Nepenthes will always be the final judge of what is bright enough, regardless of what the plant next to it is doing.)

It could be that the windows are also blocking UV light, so this one is being grumpy about it. For many other varieties it doesn't seem to matter as much. An example of this I saw this last year with some Nepenthes. I had in a window at my other job. It was a big picture West facing window with lots of direct sun. N. sanguinea and N. St. Mercury did great. N. Red Queen and N. Falcon didn't so much. They grew, but pitchered little if any. They were getting plenty of sun, but our windows in this building are Argon filled, and block 100% of UV light. I'm not sure how to recommend a way to get more unless you can just open a window to let direct sun hit that plant. 

The only other option is to use strong LED shop lights (40 watts, cool white) and bring it close to the plant. Start with 12 inches. The leaves

By the way, the plant is male. It will flower a lot, and we cut them off because they smell bad.

N. albomarginata, Black in my home, producing pitchers in winter!
It was in a west window getting direct afternoon sunlight.

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