Blue Oil Fern
Microsorum thailandicum

A striking terrestrial to epiphytic fern native to Thailand, grown for its narrow, strap-like fronds that shimmer with an iridescent blue-green metallic sheen — the "oil slick" effect most visible under bright light and at an angle. The leathery fronds have a rippled texture and grow from a creeping rhizome. A slow grower that rewards patient, consistent care and high humidity.

• Light: Bright indirect light brings out the strongest blue iridescence; avoid direct sun which scorches the fronds. Too little light diminishes the metallic sheen.

• Soil: Airy, well-draining epiphytic mix of orchid bark, perlite, and sphagnum, or mounted; the rhizome should sit at the surface. Excellent drainage and aeration essential.

• Temperature/Humidity: Warm temperatures between 65-80°F; high humidity of 70%+ is essential — well suited to terrarium or cabinet culture. Brown crispy edges signal air too dry.

• Watering: Keep consistently and evenly moist — never allow to dry out fully, never waterlog. Use rainwater or distilled water; sensitive to mineral buildup.

• Fertilizer: Feed with a balanced liquid fertilizer diluted to half strength every 4-6 weeks during active growth; reduce in winter.