The King of the Tropical Pitcher Plants, Nepenthes rajah is world famous, but still poorly represented in cultivation. Some of the reasons include there being very few clones in Tissue Culture, so there isn't any real genetic diversity to work with in horticulture; at least until seed grown plant become more common; and this species is endemic to ultramafic soils. Ultramafic soil is mostly quartz sand with high levels of iron, magnesium and also contains various heavy metals which are toxic to many species of plant not specifically adapted to live with these minerals.
While the few clones of N. rajah widely available can grow well, many times the plants fail to grow well for their owners. While thinking about how to supplement the soil with minerals and some nitrogen without adding salty chemicals found in nearly all fertilizers; which highland species abhor; I started contemplating coffee. It is made from the baked cotyledon of a baby coffee plant which is then leached with water. I figure if the salts present in the bean are rich in nutrients and speed the growth of the baby plant without causing harm; they have to be mild enough for other sensitive plants too while still providing a well balanced palate of nutrients for the plant to use--Water soluble nutrients without harsh salts.
My "clone #4" plant had been in a "holding pattern" of growth where it looked healthy, but wasn't making pitchers often and the leaves were not increasing in size. While I would feed it insects, the pitchers would then rot without the plant appearing to actually gain from the meals. And it was even starting to get smaller. Enough is enough, I decided the plant needs help and so watered it once with coffee. Nothing special about this coffee; just the leftover, stale brew from the office that usually just gets poured down the drain.
One month later; but check out the size of the new leaf!
Two months later:
And another three months later, the plant now has pitchers that do not rot when fed:
