Nepenthes rajah is comparable to that experienced in nature, since Borneo lies on the equator. Pure long-fibre "Sphagnum" moss is an excellent potting medium, though combinations involving any of the following – peat, perlite, vermiculite, sand, lava rock, pumice, "Osmunda" fibre, orchid bark and horticultural charcoal – may be used with equal success. The potting medium should be well-drained and not too compacted. Moss is useful for moisture retention near the roots. The mix should be thoroughly soaked in water prior to potting the plant. It has been noted that "N. rajah" produces a very extensive root system (for a "Nepenthes") and,
Aulacomnium palustre plant communities, and individual moss species often have low cover and/or frequency. Moss species with coverages of 2% to 4% can be common to dominant in boreal communities, although ribbed bog moss attains coverages as great as 40% in some boreal communities. Ribbed bog moss grows in open and forested wetland communities. In unforested northern communities, ribbed bog moss is found in sedge ("Carex" spp.) meadows, sphagnum ("Sphagnum" spp.) peatlands, heath-sedge fens, and willow ("Salix" spp.)-dominated fens. In forests, ribbed bog moss grows in the ground layer of boreal and subboreal white spruce ("Picea glauca"), black spruce ("P. mariana"), mixed