One needs to always consider the amount of space you will need to grow even a few of these to maturity. Imagine keeping like five so you can guarantee to have a female and male among them. These are some of the obstacles in growing many nepenthes. Of course if given more pot space and better growing areas with more light, nutrients, water-rainfall, etc. These would even get larger. Like Sam said, I also fertilize less often since good feeding by way of nutrients to roots will increase plant potential ten-fold. I feed heavily on seedlings up to a certain stage of growth and then once established, I tend to feed less making harder, more compact plants. But they still do require fertilizing to the roots to keep them alive and functional for nutrient absorption.