The Blue Oil Fern, often identified as Phlebodium aureum ‘Blue Star’ or Microsorum thailandicum, is a distinctive houseplant admired for its unique silvery-blue-green fronds. Its appealing appearance and relatively straightforward care make it a popular choice for indoor plant collections.
Understanding the Blue Oil Fern
The Blue Oil Fern is also known as Blue Star Fern or Golden Serpent Fern. Its captivating “blue oil” look comes from a waxy cuticle covering its fronds, which gives the plant its unique blue-green color and helps it retain moisture. This iridescent quality is an adaptation to its natural habitat, allowing it to capture more light in shaded understory conditions. These ferns are native to tropical and subtropical regions. Phlebodium aureum originates from the Americas, while Microsorum thailandicum is native to Southeast Asia. Both species often grow epiphytically on trees or lithophytically on rocks, attaching themselves to surfaces rather than growing directly in soil.
Caring for Your Blue Oil Fern
The Blue Oil Fern thrives with specific environmental conditions. Providing the right light, water, humidity, temperature, soil, and nutrients helps it flourish and maintain its distinctive coloration.
Light
Blue Oil Ferns prefer bright, indirect light, mimicking the dappled sunlight of their native jungle habitats. An east or north-facing window is ideal, as direct sunlight can scorch delicate fronds and diminish their vibrant blue sheen. Too much light leads to bleached or burned leaves, while insufficient light results in less vigorous growth or a paler appearance. The iridescent blue coloration is more pronounced under lower light conditions.
Water
Blue Oil Ferns require consistently moist soil, but avoid waterlogging to prevent root rot. Water when the top inch or two of soil feels dry to the touch. Allowing the soil to dry out completely is detrimental, as their roots dry quickly. Using pure water (reverse osmosis, distilled, or rainwater) is beneficial, as these ferns are sensitive to tap water minerals. Avoid getting the fuzzy rhizomes at the base of the plant excessively wet during watering.
Humidity and Temperature
High humidity (60-80%) is important for the Blue Oil Fern. Low humidity can cause frond tips to brown and become crispy. To increase humidity, place the plant on a pebble tray, group it with other plants, or use a room humidifier. They thrive in warm temperatures, typically between 18°C and 24°C (64°F to 75°F). Protect the fern from cold drafts and sudden temperature changes.
Soil and Potting
A well-draining and airy potting mix is suitable for the Blue Oil Fern. Given their epiphytic nature, an orchid or fern mix works well, providing good aeration around the roots while retaining some moisture. Repotting should be done infrequently, typically only when the plant becomes rootbound.
Fertilizing
Blue Oil Ferns are light feeders and do not require frequent fertilization; over-fertilizing can be harmful. During the active growing season (typically spring and summer), apply a balanced, diluted liquid fertilizer once or twice. Dilute to half strength or less to prevent nutrient burn, and ensure the soil is moist before fertilizing to avoid root damage.
Propagating Blue Oil Fern
Propagating the Blue Oil Fern is primarily achieved through rhizome division, the most common method for home growers. This involves gently separating the rhizomes (horizontal stems from which fronds emerge) during repotting. Each divided section should have its own roots and fronds for successful establishment. After division, plant each section into its own pot with appropriate potting mix, providing consistent moisture and warmth.
Troubleshooting Common Problems
Blue Oil Ferns can encounter issues, but recognizing them early helps maintain plant health.
Browning leaf tips or edges often indicate low humidity or inconsistent watering. Increasing ambient humidity through misting or pebble trays, and ensuring a consistent watering schedule, can alleviate this.
Yellowing fronds may suggest overwatering, a nutrient deficiency, or too much direct light. Adjusting watering practices to allow the topsoil to dry slightly and checking light conditions can resolve this. If the plant is overwatered, root rot can occur, characterized by black or mushy roots, requiring prompt action like repotting into fresh soil after trimming affected roots.
Common houseplant pests such as spider mites or mealybugs can affect Blue Oil Ferns. Regular inspection of fronds and undersides of leaves allows for early detection. Organic treatment methods, such as wiping leaves with a damp cloth or applying insecticidal soap or neem oil, can help manage infestations.
A loss of the characteristic blue sheen can happen if the plant is not receiving ideal light conditions, as the blue coloration is often more pronounced in lower, indirect light.