Microsorum grossum, commonly known as the Alligator Fern or Crocodile Fern, is a unique plant with distinctive foliage. Its vibrant green fronds have a textured, leathery surface resembling alligator or crocodile skin, giving the plant its popular names. Native to the humid rainforests of Southeast Asia, the Pacific Islands, and tropical Australia, this tropical fern thrives in warm, moist environments. In its natural habitat, it often grows as an epiphyte, attaching itself to trees for support.
Caring for Your Microsorum grossum
Light Requirements
Alligator ferns prefer bright, indirect light. Placing them near a north-facing window or in a spot where they receive filtered sunlight is ideal. Direct sun exposure, particularly intense afternoon sun, can scorch their fronds, leading to brown, crispy spots on the leaves. If fronds appear pale or yellowish, it might indicate too much light, while sparse growth or very dark green leaves could suggest insufficient light. Adjusting the plant’s position to a brighter or slightly shadier location can help balance its light intake.
Watering Needs
Maintaining consistent moisture in the soil is important for the Alligator Fern, but it should never be waterlogged. Water thoroughly when the top inch or two of soil feels dry to the touch. Ensure the pot has drainage holes to allow excess water to escape, preventing root rot. Signs of underwatering include wilting or browning leaf edges, while yellowing leaves often signal overwatering.
Humidity and Temperature
Microsorum grossum thrives in high humidity, ideally above 60%. To increase ambient moisture, consider using a pebble tray filled with water beneath the plant, ensuring the pot does not sit directly in the water. Regularly misting the fronds or placing a humidifier nearby can also provide the necessary humidity. The plant prefers temperatures between 65°F and 85°F (18°C-29°C) and is sensitive to sudden temperature changes or cold drafts.
Soil and Potting
A well-draining, airy potting mix rich in organic matter is suitable for Alligator Ferns. A standard fern mix, an aroid potting mix, or a blend of peat moss, perlite, and pine bark promotes healthy root development. As epiphytes, they appreciate good air circulation around their roots.
Fertilizing
During the active growing season (typically spring and summer), a diluted liquid fertilizer can support the fern’s growth. Apply a balanced houseplant fertilizer at half the recommended strength every two to four weeks. Over-fertilization can lead to fertilizer burn, damaging the roots and foliage. Avoid high-nitrogen fertilizers, which can encourage excessive leafy growth at the expense of overall plant health.
Propagating Microsorum grossum
Propagating Microsorum grossum is most effectively achieved through division. The ideal time to divide the plant is during repotting, usually when the fern has outgrown its current container.
Remove the plant from its pot and gently tease apart the root ball, identifying natural divisions in the rhizome. Using a sterile cutting tool, cut the rhizome into sections, ensuring each section has at least a few healthy fronds and a portion of the root system attached.
Plant these divisions into separate pots filled with well-draining potting mix. After repotting, provide the new plants with consistent moisture and indirect light to help them establish.
Troubleshooting Common Problems
If the leaf tips or edges begin to brown, it often indicates low humidity, underwatering, or a buildup of mineral salts from tap water. Increasing humidity, ensuring consistent soil moisture, and using distilled or filtered water can alleviate this problem.
Yellowing leaves are frequently a sign of overwatering, which can lead to root rot. Allowing the soil to dry slightly between waterings and ensuring proper drainage can help prevent this.
Stunted growth may point to insufficient light or a lack of nutrients. Moving the plant to a brighter location with indirect light and applying a diluted fertilizer can encourage healthier growth.
Pests such as spider mites, scale, and mealybugs can occasionally affect Alligator Ferns. Inspect plants regularly and treat infestations with insecticidal soap or neem oil.