Question
I have been growing(very succesfully) many highland Nepenthes for 10 years in a greenhouse in coastal northern California (Eureka). Have had a Nepenthes raja for 7 years and it grows but never forms traps.  Medium lighting, soil mix of peat, chips, charcoal, sphagnum, perlite), lots of water, highland temp requirements, foliar fertilizing (very weak solution of orchid fertilizer),etc.  Why no traps? Very frustrating. Thanks.

Answer
You're definitely not alone with a pitcherless Nepenthes rajah.  This plant is notorious for not producing pitchers unless the conditions are perfect.  Even for us, we have trouble getting this species to produce pitchers.  We might get one or two pitchers on a plant, but they're often rather small.  

This plant grows in sub-alpine terrain where they experience full sun and cool temperatures.  Day temperatures should be 65?80癋.  Night temperatures should fall in the low 50s to mid 40s.  You didn't mention anything about lighting, so I suspect you may not be giving your plant enough light.  When you see photos of this plant in the wild, you will see it growing amongst the grass and low strubs.  There are essentially no trees in the environment, so this plant gets plenty of sunlight.  Because the plant grows at a very high elevation, the temperature is also quite cool.  

In cultivation, it's difficult to give this plant the lighting it needs without burning it.  One grower in Colorado managed to get very large pitchers on his plant.  He has no problem with getting plenty of direct sunlight in his region, but he uses swamp coolers and misters to keep the temperature below 80.  

I imagine that the coastal climate in your region is very cloudy, much like the Oregon Coast.  If that's the case, you may need to use artificial lights during the winter months.  Winter would be your best chance to see pitchers on your rajah since the temperatures are more ideal.  You'll just need to supplement with very strong fluorescent lights, such as T5.  

Good growing!
Jacob Farin