Selaginella uncinata (Rainbow Moss)

Selaginella uncinata is a spikemoss native to subtropical China, widely cultivated as a terrarium and paludarium groundcover for its extraordinary iridescent blue-green foliage — an optical effect caused by the same thin-film interference mechanism that produces colour in peacock feathers. Under the right lighting conditions the fronds shimmer between teal, blue, and violet, creating a jewel-like carpet across the land zones of paludariums.

It is a vigorous creeper that spreads horizontally, rooting from nodes wherever it contacts moist substrate or hardscape. It tolerates low light and high humidity exceptionally well, making it one of the most reliable groundcover plants for enclosed terrarium and paludarium builds. Occasional trimming keeps the mat dense and prevents leggy growth.

Light: Low to medium indirect; 500–2,000 lux; iridescence is most vivid at medium light intensity. CO2/Humidity: No CO2; humidity above 70% essential; keep substrate consistently moist but not waterlogged. Fertilisation: Light monthly fertilisation with dilute all-purpose fertiliser; avoid excess nitrogen which causes excessive growth. Placement: Plant directly into moist substrate or press against damp hardscape; it will self-attach via adventitious roots. Propagation: Stem cuttings root easily; press cut sections onto moist substrate and they establish within weeks.