Boston Fern

Overview

The Boston Fern (Nephrolepis exaltata) is a classic houseplant beloved for its graceful, arching fronds and lush appearance. Native to humid forests and swamplands in tropical regions, this fern has been a popular indoor plant since the Victorian era, when it adorned parlors and sunrooms in hanging baskets and on pedestals.

With its feathery, sword-shaped fronds that can grow up to 3 feet long, the Boston Fern creates a dramatic cascading effect that softens interior spaces. Each frond consists of many small leaflets (pinnae) arranged along a central stem (rachis), giving the plant its characteristic fluffy, delicate appearance.

Beyond its ornamental value, the Boston Fern is known for its air-purifying qualities. NASA studies have shown it effectively removes formaldehyde and other toxins from indoor air. It's also completely non-toxic to pets and humans, making it a safe choice for households with children and animals.

While Boston Ferns have a reputation for being somewhat finicky, understanding their tropical origins helps explain their care needs. With proper attention to humidity and watering, these beautiful ferns can thrive indoors, bringing a touch of lush woodland beauty to your home for many years.

Care Guide

Light Requirements

Boston Ferns thrive in bright, indirect light that mimics the dappled sunlight they would receive on the forest floor in their natural habitat:

• Medium to bright indirect light: Ideal for healthy growth and lush foliage
• Low light: Will survive but growth will slow and fronds may become sparse
• Direct sunlight: Avoid as it will scorch the delicate fronds
• Artificial light: Can thrive under fluorescent lights, making them suitable for offices

For optimal growth, place your Boston Fern near an east-facing window where it will receive gentle morning sun, or a few feet away from a south or west-facing window where direct sunlight won't reach the fronds. In very bright locations, a sheer curtain can help filter the light to appropriate levels.

The color of your fern's fronds can indicate whether it's receiving the right amount of light. Vibrant green fronds suggest optimal light conditions, while pale or yellowing fronds may indicate too much light. Conversely, unusually dark green fronds might signal insufficient light.

Watering

Consistent moisture is crucial for Boston Ferns, as they naturally grow in humid environments with regular rainfall:

Watering Schedule:

• Keep soil consistently moist but not soggy
• Water when the top inch of soil feels slightly dry
• Typically this means watering 2-3 times per week in summer
• Reduce to once weekly in winter when growth slows
• Never allow the soil to dry out completely

Watering Technique:

• Water thoroughly until it flows from the drainage holes
• Use room temperature water, as cold water can shock the roots
• Water the soil directly, avoiding the crown of the plant
• If possible, use rainwater or filtered water, as Boston Ferns can be sensitive to chemicals in tap water

Boston Ferns will signal when they need water by drooping slightly. However, don't wait until this point to water, as consistent moisture is important for these plants. If the soil becomes completely dry, the fronds may turn brown and crispy, and recovery can be difficult.

For hanging Boston Ferns, it can be helpful to take them down and place them in a sink or bathtub for thorough watering, allowing them to drain completely before hanging them back up.

Soil

Boston Ferns thrive in rich, organic soil that retains moisture while still providing good drainage:

Ideal Soil Mix:

• 2 parts peat moss or coco coir
• 1 part perlite or vermiculite
• 1 part standard potting soil

This combination creates a light, airy mix that holds moisture without becoming waterlogged. The high organic content mimics the forest floor conditions where Boston Ferns naturally grow.

Soil pH:

• Boston Ferns prefer slightly acidic soil with a pH between 5.0 and 5.5
• Peat moss naturally provides this acidity
• If using coco coir (which is pH neutral), you may need to slightly acidify the soil

Repot your Boston Fern every 1-2 years in spring, or when it becomes root-bound. Choose a pot that's only 1-2 inches larger in diameter than the current one, as too large a pot can hold excess moisture and lead to root rot. Boston Ferns generally prefer to be slightly root-bound rather than having too much space.

Temperature & Humidity

As tropical plants, Boston Ferns have specific temperature and humidity requirements that reflect their native environment:

Temperature:

• Ideal range: 65-75°F (18-24°C)
• Minimum temperature: 55°F (13°C)
• Avoid temperatures above 95°F (35°C)
• Keep away from cold drafts, heating vents, and air conditioners

Humidity:

• Requires high humidity (50-80%)
• Will struggle in dry environments below 40% humidity
• Increase humidity through these methods:
  • Use a humidifier near the plant
  • Place on a pebble tray with water
  • Group with other plants to create a microclimate
  • Mist fronds daily, especially in winter
  • Place in naturally humid rooms like bathrooms (if adequate light is available)

Humidity is particularly crucial for Boston Ferns. In low humidity, fronds will develop brown tips and edges, and the plant may drop leaflets. If you notice these signs, take immediate steps to increase humidity around your fern.

During winter, when indoor heating systems reduce humidity, you may need to combine several humidity-boosting methods to keep your Boston Fern happy. A hygrometer can be a helpful tool to monitor humidity levels around your plant.

Fertilizing

Boston Ferns benefit from regular but gentle fertilization during their growing season:

Fertilizing Schedule:

• Apply a balanced, water-soluble houseplant fertilizer diluted to half the recommended strength
• Fertilize monthly during spring and summer (active growth period)
• Reduce to once every 2-3 months in fall
• Stop fertilizing completely in winter when growth naturally slows

Fertilizing Tips:

• Always apply fertilizer to moist soil to prevent root burn
• Flush the soil thoroughly every few months to prevent salt buildup
• Organic fertilizers like fish emulsion or worm castings can be gentler alternatives
• Avoid fertilizers high in nitrogen, which can cause brown frond tips

Boston Ferns are not heavy feeders, and too much fertilizer can cause more harm than good. Signs of over-fertilization include brown tips on fronds, a white crust on the soil surface, and stunted growth. If you notice these symptoms, flush the soil thoroughly with water and reduce your fertilizing frequency.

Propagation

Boston Ferns can be propagated through division or by planting the plantlets that develop on mature specimens:

Division Method:

1. Remove the plant from its pot during repotting in spring
2. Gently separate the root ball into smaller sections, ensuring each division has several fronds and a good portion of the root system
3. Plant each division in its own pot with fresh soil
4. Water thoroughly and place in a warm, humid location with indirect light
5. Keep the soil consistently moist until new growth appears

Plantlet/Runner Method:

1. Some Boston Ferns produce small plantlets on runners (stolons)
2. Wait until these plantlets develop small fronds and roots
3. While still attached to the mother plant, pin the plantlet to a small pot filled with moist soil
4. Once the plantlet is established (usually after 3-4 weeks), cut it from the mother plant
5. Continue to care for the new plant as you would a mature Boston Fern

Spore Propagation: While Boston Ferns can be grown from spores (visible as brown dots on the undersides of mature fronds), this method is complex and time-consuming, requiring sterile conditions and specialized knowledge. Division is generally the easiest and most reliable propagation method for home gardeners.

The best time to propagate Boston Ferns is during spring or early summer when the plant is actively growing. Newly propagated ferns may take some time to establish, but with patience and consistent care, they will develop into full, lush plants.

Common Problems

While Boston Ferns are generally resilient, they can experience several common issues:

Brown Tips or Edges on Fronds:

• Cause: Low humidity, underwatering, or fertilizer buildup
• Solution: Increase humidity, adjust watering schedule, and flush soil occasionally to remove mineral buildup

Yellowing Fronds:

• Cause: Overwatering, poor drainage, or normal aging of older fronds
• Solution: Adjust watering frequency, ensure proper drainage, and remove only completely yellow fronds

Dropping Leaflets:

• Cause: Low humidity, sudden temperature changes, or dry soil
• Solution: Increase humidity, maintain stable temperatures, and ensure consistent soil moisture

Pale or Bleached Fronds:

• Cause: Too much direct sunlight
• Solution: Move to a location with appropriate indirect light

Pests:

• Spider Mites: Tiny pests that cause stippling on fronds and fine webbing, particularly in dry conditions
• Mealybugs: White, cotton-like insects that cluster in leaf joints
• Scale: Small, brown bumps on stems and frond undersides
• Solution: Increase humidity (for spider mites), wipe fronds with insecticidal soap or neem oil, isolate affected plants

Stunted Growth:

• Cause: Insufficient light, nutrients, or being severely root-bound
• Solution: Ensure adequate indirect light, appropriate fertilization, and repot if necessary

Root Rot:

• Cause: Overwatering, poor drainage, or compacted soil
• Solution: Reduce watering frequency, ensure pot has drainage holes, and consider repotting in fresh, well-draining soil

Most Boston Fern problems can be resolved by adjusting care routines to better match their tropical preferences, particularly regarding humidity and watering.

Popular Varieties

The Boston Fern family includes several attractive cultivars, each with unique characteristics:

Nephrolepis exaltata 'Bostoniensis' (Classic Boston Fern)

• The original Boston Fern variety
• Long, arching fronds with a classic feathery appearance
• Can grow quite large, with fronds reaching 2-3 feet in length
• Perfect for hanging baskets where fronds can cascade

Nephrolepis exaltata 'Fluffy Ruffles'

• More compact growth habit than the classic Boston Fern
• Fronds have a distinctly ruffled, curly appearance
• Denser growth creates a fuller look
• Good choice for smaller spaces

Nephrolepis exaltata 'Dallas'

• Compact variety with shorter fronds
• More tolerant of lower humidity than other varieties
• Maintains a neater appearance with less dropping of leaflets
• Ideal for tabletops and smaller containers

Nephrolepis exaltata 'Rooseveltii' (Roosevelt Fern)

• Wider fronds than the classic Boston Fern
• Leaflets are more ruffled and overlapping
• Creates a particularly lush, full appearance
• Named after President Theodore Roosevelt

Nephrolepis exaltata 'Compacta' (Dwarf Boston Fern)

• Significantly smaller than standard Boston Ferns
• Grows only 10-12 inches tall and wide
• Perfect for small spaces and terrariums
• Requires the same care as larger varieties

Nephrolepis exaltata 'Tiger Fern'

• Features distinctive yellow-green striping on the fronds
• Slightly more compact than the classic Boston Fern
• Requires bright indirect light to maintain variegation
• Adds visual interest to fern collections

While all these varieties share the same basic care requirements, those with more compact growth habits may be slightly more forgiving of lower humidity levels. The variegated types typically need brighter light to maintain their distinctive coloration.

With their graceful, arching fronds and air-purifying qualities, Boston Ferns make a classic addition to any indoor plant collection. While they require attention to humidity and watering, the lush, woodland beauty they bring to interior spaces makes them well worth the extra care.