The Blue Oil Fern (Microsorum thailandicum) is an extraordinary plant known for its metallic, iridescent blue leaves that shimmer under the right light. Native to parts of Southeast Asia, this fern has become popular among collectors for its otherworldly coloration that looks almost unreal. Its leaves are thick and leathery compared to typical ferns, which makes it more resilient and gives it a bold, striking appearance in any collection.
The direction of light has a huge impact on how its unique blue sheen shows. Bright, indirect light is best—an east-facing window provides gentle morning rays that bring out its metallic tones, while a south-facing window filtered with sheer curtains maintains consistent brightness without causing burns. In a north-facing window, the fern may survive but lose some of its vivid iridescence, while west-facing light needs to be softened to prevent heat stress. Positioning it carefully so it catches consistent, indirect brightness is key to highlighting its stunning coloration.
In terms of care, the Blue Oil Fern prefers evenly moist, well-draining soil and higher humidity to mimic its native rainforest environment. It doesn’t tolerate drying out completely, but it also shouldn’t sit in soggy soil.
Blue Oil Fern can be mounted, but it does require a little extra attention compared to when it’s grown in a pot. Because it’s an epiphytic fern in nature, it can thrive mounted on wood, cork, or tree fern plaques, where its roots attach and spread just like they would in the wild. When mounted, the leaves often display their iridescent blue sheen even more beautifully, since air circulation is improved and the plant sits in a more natural position.
The challenge with mounting is keeping the root zone consistently moist. In a pot, the soil holds water longer, but on a mount, the plant dries out quickly. This means you’ll need to mist daily or soak the entire mount several times per week, especially if your home has lower humidity. A humidifier or terrarium setup can make mounted care much easier. If your environment is naturally humid, mounting is a great way to showcase its foliage and unique color.
Regular misting or a humidifier can help maintain the moisture levels it loves. With the right balance of watering, humidity, and especially correct light direction, the Blue Oil Fern rewards growers with foliage that looks like it belongs in a fantasy world.
