The Cabbage Fern, scientifically known as Blechnum brasiliense, is a visually appealing plant prized for its ornamental qualities, whether grown indoors as a houseplant or outdoors in suitable climates. Its striking appearance features dark green, leathery fronds and new growth emerging in vibrant shades of red or bronze. Young fronds often unfurl resembling a compact “cabbage” head, contributing to its common name.
Understanding Cabbage Fern
The Blechnum brasiliense, often referred to as the Brazilian Tree Fern or Red Dwarf Tree Fern, is an evergreen subshrub native to the wet tropical climates of South and Central America. This fern forms a central rhizome that can develop into a thin, trunk-like structure over time, reaching up to 30-70 cm in height in mature specimens.
Its fronds are a notable feature, typically growing between 3 to 6 feet wide and tall, forming an attractive, arching rosette. New fronds emerge with an intense pinkish-red or reddish-bronze hue, which gradually transitions to bronze and then a glossy, dark green as they mature. These fronds are pinnate or pinnatifid, meaning they are divided into many toothed, linear segments, creating a finely textured, feather-like appearance.
Caring for Cabbage Ferns
Light
Cabbage Ferns thrive in environments that mimic their natural shaded understory habitat. They prefer bright, indirect, or filtered light conditions. Indoors, an east or north-facing window is often suitable, or a sheer curtain can diffuse intense light. Direct sunlight should be avoided as it can easily scorch delicate fronds.
Water
Consistent moisture is important for the Cabbage Fern, as it prefers perpetually damp but not waterlogged soil. The soil should be kept consistently moist, watering when the top inch feels slightly dry. Using distilled or rainwater is beneficial to prevent mineral buildup.
Soil
A well-draining soil mix rich in organic matter is ideal for Blechnum brasiliense. A suitable blend might include peat, perlite, and compost, which provides both moisture retention and proper drainage. The fern generally prefers a slightly acidic to neutral soil pH.
Temperature and Humidity
These ferns flourish in moderate temperatures, ideally ranging from 65°F to 75°F (18°C to 24°C). High humidity is particularly important, with optimal levels between 60% to 80%. To maintain sufficient humidity, consider placing the plant on a pebble tray, using a humidifier, or grouping it with other plants. Regular misting also helps.
Fertilizer
During the active growing season (typically spring and summer), Cabbage Ferns benefit from regular fertilization. Apply a balanced liquid fertilizer with an N-P-K ratio such as 10-10-10, diluted to half or quarter strength, monthly. A slow-release product can also be applied tri-annually. Reduce or stop fertilization during fall and winter when growth slows.
Propagation and Pruning
Cabbage Ferns can be propagated through two primary methods: division and spores. Division is the more straightforward method for home growers. This involves carefully separating offsets or sections of the rhizome from the main plant, ensuring each new section has healthy roots and fronds. The best time for division is typically in the spring or early summer during the plant’s active growth period.
Propagating by spores is a more advanced and time-consuming process. Spores are collected from the underside of mature fronds when ripe, typically appearing as tiny brown spots. Sow these on a sterile, moist growing medium in a humid environment. Germination can take several weeks to months before tiny plantlets emerge.
Pruning is generally minimal for Blechnum brasiliense. It is not required for overall plant structure. The main purpose of pruning is to maintain the plant’s appearance and health by removing any old, yellowing, or damaged fronds. This selective removal encourages new growth and helps the plant direct energy towards healthy foliage.
Common Issues and Solutions
Browning leaf tips or edges often indicate insufficient humidity or inconsistent watering. Increase ambient humidity (misting or pebble tray) and ensure consistently moist soil.
Yellowing fronds can signal overwatering, poor drainage, root problems, nutrient deficiency, or natural aging. Adjusting watering and fertilization can address these.
Cabbage Ferns can attract common houseplant pests like spider mites or mealybugs, especially in dry conditions. Regular inspection helps early detection. Treatment involves wiping affected areas with a damp cloth or applying insecticidal soap.
A lack of new growth may suggest inadequate light, insufficient nutrients, or incorrect temperature conditions. Ensure the plant receives bright, indirect light, appropriate fertilization during the growing season, and stable temperatures to encourage renewed growth.