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,
Sphagnum cuspidatum capitulum. "Sphagnum cuspidatum" is a dominant species in the bogs that it inhabits. In wetlands, they consume methane through symbiosis with partly endophytic methanotrophic bacteria, leading to highly effective in situ methane recycling preventing large-scale methane emission into the atmosphere. The bacteria are present in the hyaline cells of the plant. Sometimes, Sphagnum moss can be infected with another type of fungus that can cause sporotrichosis. The other fungus can enter the body through cuts or scrapes on the skin, and will then cause ulcerous skin lesions. It is therefore advised to wear gloves and long sleeves when handling sphagnum