Rainbow Fern

The Rainbow Fern (Selaginella uncinata) is a stunning, iridescent groundcover that shimmers with metallic blue-green hues in shifting light. Native to subtropical China, this ancient spikemoss relative produces dense, overlapping fronds that catch and refract light like a prism — making it one of the most visually striking terrarium and vivarium plants available.

Care Guide

Light

Thrives in bright, indirect light. Avoid direct sun, which will bleach the iridescent coloration. Low to medium light is tolerated, though the metallic shimmer is most vivid under diffused bright light or full-spectrum grow lights.

Water

Keep the substrate consistently moist but never waterlogged. Rainbow Fern prefers high ambient humidity (60–90%) and does exceptionally well in closed or semi-closed terrariums. Allow the top layer of substrate to remain just barely damp between waterings.

Humidity

High humidity is essential — 70% or above is ideal. Misting, pebble trays, or enclosed terrarium environments are strongly recommended for long-term success.

Temperature

Prefers temperatures between 60–80°F (15–27°C). Protect from cold drafts and temperatures below 50°F (10°C).

Soil & Substrate

Use a well-draining, moisture-retentive mix — a blend of peat or coco coir, perlite, and orchid bark works well. Terrarium substrate mixes are ideal.

Fertilizer

Feed lightly with a diluted balanced liquid fertilizer (quarter strength) once a month during the growing season (spring–summer). Avoid over-fertilizing, which can damage delicate fronds.

Repotting

Repot only when root-bound, typically every 1–2 years. Handles best in shallow, wide containers that allow lateral spreading.

Toxicity

Non-toxic to humans and pets.