The Boston Fern (Nephrolepis exaltata bostoniensis) is a popular houseplant, celebrated for its voluminous, arching green fronds. It brings a natural, lush element to any indoor space.
Understanding Your Boston Fern
The Boston Fern originates from tropical regions like South America, Central America, Florida, and the West Indies, thriving in humid, shaded forest undergrowth. This explains its preference for consistent moisture and indirect light. Its characteristic frilly, sword-shaped fronds can reach 4 feet, emerging from a central rosette to create a dense display. The Boston Fern is also valued for its air-purifying qualities, reportedly removing common indoor pollutants.
Boston Fern Care Guide
Boston Ferns flourish when their environment mimics their native tropical origins. Consistent care across several key areas ensures vibrant green foliage and robust growth.
Light
Boston Ferns thrive in bright, indirect light, imitating dappled forest sunlight. A north or east-facing window is ideal, or a south or west-facing window if the light is diffused with a sheer curtain. Too much direct sunlight, especially midday, can scorch fronds, leading to browning. Insufficient light may result in sparse, pale fronds and stunted growth.
Watering
Consistent moisture is important for Boston Ferns, as they do not tolerate drying out. The soil should remain evenly moist but never waterlogged, which can lead to root rot. Water thoroughly until excess water drains from the pot, then empty any collected water from the saucer. Check the top inch or two of soil for dryness before watering to prevent over or under-watering. During spring and summer, water every 2-3 days; in fall and winter, reduce frequency to once a week or every other week as growth slows.
Humidity
High humidity is important for Boston Ferns, which prefer levels above 60-70%, ideally around 80%. Low humidity often causes frond tips to turn brown and crispy. To increase humidity, regular misting is helpful, especially in dry indoor environments. Other methods include placing the pot on a pebble tray filled with water (ensuring the pot is not submerged) or using a room humidifier. Grouping plants together can also create a localized microclimate with higher humidity.
Temperature
Boston Ferns prefer stable, moderate temperatures, ideally 65-75°F (18-24°C) during the day. Nighttime temperatures should not drop below 55°F (13°C) and can range up to 65°F (18°C). These ferns are sensitive to extreme temperature fluctuations and cold drafts, which can harm the plant. Keep them away from air conditioning vents, heating units, or drafty windows to maintain consistency.
Soil and Potting
A well-draining yet moisture-retentive soil mix is ideal for Boston Ferns. An organic, loamy soil, often peat-based with added perlite or vermiculite, provides balanced drainage and water retention. Good drainage is important to prevent waterlogging and root rot. When potting, choose containers with ample drainage holes. Repotting is best done in spring when roots emerge from drainage holes, indicating the plant is root-bound.
Fertilizing
Boston Ferns are not heavy feeders, but they benefit from moderate fertilization during their active growing season. During spring and summer, a balanced liquid houseplant fertilizer (e.g., 20-10-20 NPK) applied at half strength once a month or every 4-6 weeks is sufficient. Water the plant before fertilizing to prevent root burn. Reduce or stop fertilization entirely in late fall and winter when the plant’s growth slows.
Pruning
Pruning Boston Ferns maintains appearance and promotes healthier growth. The primary goal is to remove any yellowing, brown, or dead fronds, trimmed at their base using clean, sharp shears. This encourages new growth and improves air circulation, which helps prevent fungal issues. While routine removal of discolored foliage can occur anytime, more severe pruning to reshape the plant or remove leggy growth is best done in spring or summer, often coinciding with repotting.
Propagating Boston Ferns
Propagating Boston Ferns is primarily achieved through division, the most accessible method for home gardeners. This technique is useful when a fern has outgrown its pot or when creating new plants from an existing one. Division also helps rejuvenate an older, root-bound plant.
To propagate by division, remove the mature Boston Fern from its pot. Shake off excess soil to expose the root ball. Using a sharp, sterilized knife or garden forks, divide the root ball into smaller sections, ensuring each has healthy roots and fronds. Plant each section into its own pot with fresh, well-draining potting mix.
After potting, water thoroughly and keep them in a warm, bright spot with indirect light and high humidity to encourage establishment. This process is best performed during the plant’s active growing season, typically spring or early summer, for recovery and new growth.
Common Boston Fern Problems
Boston Ferns can exhibit issues signaling a need for care adjustment. Browning or crisping frond tips indicate low humidity or inconsistent watering. Increasing humidity through misting or pebble trays, and ensuring consistently moist soil, helps alleviate this. Yellowing fronds might suggest overwatering or insufficient humidity. Checking soil moisture and adjusting watering frequency, along with boosting humidity, remedies this.
Drooping fronds are often related to watering issues. Both under-watering (dry soil) and overwatering (leading to root rot) cause drooping. Feeling the soil to assess its moisture level is important; if dry, water deeply, but if wet and drooping, allow the soil to dry out slightly before the next watering to prevent root damage. Pests like spider mites, mealybugs, and scale insects can also affect Boston Ferns. Spider mites appear in dry conditions, causing tiny webs and speckled leaves; mealybugs are cottony white masses; and scale insects are small, flat bumps. Isolating affected plants and treating with insecticidal soap or neem oil helps manage these infestations.