Nepenthes merrilliana is one of the biggest pitchering Nepenthes there is. I can't recall how big they get, but they're monsters! I tried growing it outdoors with my others but it didn't do too well. There was leaf and tendril curl due to the fact that this plant is really a lowlander and best treated that way. Since then I have moved into my bedroom and it is doing well. I have had difficulty getting this species to produce pitchers as a houseplant in lower humidity similar to N. northiana and N. bicalcarata. The plant grows well but some vendors have told me that N. merrilliana really does like those hot, humid, true lowland conditions. I'm beginning to agree. I've been able to sustain good growth, but no pitcher production. The tendrils dry up at the ends. This plant may fall into the category of Nepenthes that doesn't do well in lower humidity household conditions and should be grown exclusively in greenhouses with high humidity. So if you try to grow this guy give him plenty of room, heat, and humidity and you should do well.
RATING
lowlander 20m-1700m
Cultivation: difficult to impossible outdoors in
highland conditions; very difficult to pitcher as an indoor houseplant;
a vigorous grower under normal lowland, greenhouse conditions, gets very
large!
Market availability: size 3 and larger;
common
Species variability: none that I'm aware of other
than locality differences
$ / size: inexpensive $10.00 and up
Cuttings: none available for trade
Sex: unknown