Complete Guide To Boston Fern Care and Growth

Quick Overview

The Boston Fern, or Fishbone Fern (Nephrolepis exaltata), is a graceful, arching plant renowned for its lush green fronds. Native to humid forests and swamps from northern South America to Mexico and Central America, it’s a classic houseplant that brings a touch of the tropics indoors.

Boston ferns are evergreen plants that can grow up to 3 feet tall and wide, with fronds reaching up to 4 feet long. Their sword-shaped, blue-green foliage contains tiny leaflets that grow erect and arch gracefully as they mature. Caring for a Boston fern involves providing bright, indirect light, high humidity, and consistently moist soil. While they require some attention to these needs, their vibrant foliage makes them a rewarding addition to any plant collection. They are non-toxic to pets and humans and are excellent air purifiers.

Looking for more air-cleaning plant options? Check out our 👉 Air-Purifying Indoor Plants guide.

How much light does a Boston Fern need?

Boston Ferns thrive in bright, indirect light. They should be placed in a spot that ideally receives 2-3 hours of gentle morning or late afternoon sunlight daily. It’s crucial to avoid direct, intense sunlight, especially midday sun, as it can scorch and damage the delicate fronds.

The ideal light levels for Boston Ferns range from 10,000-12,000 lux. You can measure light intensity with a light meter to find the perfect spot.

Indoor Lighting

Outdoor Lighting

Signs of Lighting Issues

• Insufficient Light: Slow growth, smaller fronds, fronds turning yellow or brown.
• Excessive Light: Dry, brown leaf tips; burnt, crispy fronds.

By providing the proper level of bright, indirect light, you can keep your Boston Fern healthy and vibrant. Monitor your plant closely and adjust its position as needed throughout the seasons to maintain lush, vigorous growth.

How to Water a Boston Fern

Watering Frequency

• During the growing season (spring and summer), water your Boston Fern 1-2 times per week.
• In winter, when growth slows, reduce watering frequency. Allow the top 1-2 inches of soil to dry out between waterings. Always check the soil moisture by touching the surface; if it feels slightly dry, it’s time to water. For precise moisture monitoring, consider using a moisture meter to check deeper soil levels. The top inch should feel slightly dry before watering again.

Watering Technique

• Use lukewarm water to avoid shocking the plant’s roots.
• Water the plant thoroughly until water drains from the bottom of the pot, ensuring the soil is completely damp but not waterlogged.
• Allow the plant to drain properly after watering. Never let the pot stand in water, as this can lead to root rot.

Signs of Improper Watering

• Overwatering: Yellowing leaves, wilted leaves, root rot (a musty smell from the soil).
• Underwatering: Dry, crispy leaves; shedding leaves; slow growth.

Tips for Maintaining Proper Moisture

• Use a well-draining potting mix.
• Increase humidity around the plant by placing it on a pebble tray, using a humidifier, or misting regularly. The frequency and amount of water required may vary depending on pot size, soil type, and environmental conditions (temperature and humidity). Adjust your watering routine accordingly.

Ideal Soil Characteristics

Recommended Soil Mix

A good basic soil mix for Boston Ferns can be made with:

• 1 part peat moss or coco coir (for moisture retention and acidity)
• 1 part perlite or vermiculite (for drainage and aeration)
• 1 part quality potting soil (for nutrients) Alternatively, you can use a pre-mixed indoor potting soil formulated for ferns or an orchid mix, often amended with extra perlite.

Maintaining Acidic pH

Moisture and Drainage

Indoor vs. Outdoor Soil

Why Fertilize?

Type and Frequency

• Use a balanced, water-soluble houseplant fertilizer, typically with an NPK ratio like 20-20-20.
• Dilute the fertilizer to half the strength recommended on the product label to avoid fertilizer burn.
• Fertilize every 2-4 weeks during the spring and summer.
• Discontinue fertilizing in the fall and winter when the plant’s growth naturally slows down.

Alternative Fertilizers

• Slow-release fertilizer pellets can be applied in the spring, providing a steady supply of nutrients for 6-8 weeks.
• For organic options, consider using compost tea, fish emulsion, or liquid kelp, following product instructions for dilution and frequency.

Signs of Nutrient Deficiency

• Yellowing or pale leaves
• Stunted or slow growth
• Increased leaf drop If you observe these signs, and other conditions like light and water are optimal, your fern may need feeding. Always water the plant before fertilizing to protect the roots.

Ideal Temperature Range

Indoor Temperature Considerations

Outdoor Temperature Considerations

Signs of Temperature Stress

• Too hot or too cold: Browning or drying leaves.
• Too cold: Wilted leaves, slow growth. By maintaining the proper temperature range and avoiding sudden fluctuations, you can ensure a healthy and thriving Boston Fern.

Importance of Humidity

How to Increase Humidity

To create a more humid environment for your Boston Fern, especially in dry indoor settings, consider these methods:

• Misting: Mist the plant with room-temperature water once or twice a day. This provides a temporary boost in humidity around the fronds.
• Pebble Tray: Place the fern’s pot on a tray filled with pebbles and water. Ensure the bottom of the pot is not sitting directly in the water, but above it on the pebbles. As the water evaporates, it increases humidity around the plant.
• Grouping Plants: Group your Boston Fern with other humidity-loving plants. Transpiration from multiple plants creates a more humid microclimate.
• Humidifier: Use a room humidifier, especially during winter when indoor heating can dry out the air.
• Location: Place the fern in naturally more humid rooms, like a bright bathroom or kitchen, provided light conditions are adequate.

Signs of Low Humidity Stress

• Brown or dry leaf tips
• Yellowing leaves
• Increased leaf drop
• Crispy frond edges By maintaining adequate humidity levels, you can ensure your Boston Fern remains healthy, with vibrant and lush foliage.

Do Boston Ferns Flower?

Spore Production

Spores are tiny, single-celled reproductive units. On Boston Ferns, these spores develop in structures called sori (singular: sorus), which appear as small, brown or black dots or lines on the underside of mature fronds. These sori are sometimes mistaken for pests or diseases by new fern owners.

The production of spores can occur throughout the year, with many varieties releasing mature spores in spring, summer, fall, and winter, depending on conditions. When the spore capsules (sporangia) within the sori are mature and typically brown and powdery, they rupture to release the spores into the air. These spores, if they land in a suitable moist environment, can germinate and begin the fern’s complex life cycle, eventually developing into new fern plants.

Popular Boston Fern Varieties

The classic Boston Fern (Nephrolepis exaltata ‘Bostoniensis’) is just the beginning. The world of Boston Ferns is incredibly diverse, with dozens of cultivars offering unique textures, sizes, and even colors. From the densely ruffled ‘Fluffy Ruffles’ to the upright-growing ‘Kimberly Queen’ and the strikingly variegated ‘Tiger Fern’, there is a variety to suit any space and aesthetic.

To explore the full range of options, from compact ferns perfect for a desk to large, dramatic specimens, see our detailed guide.

👉 Explore 42 Different Boston Fern Varieties (With Pictures)

Choosing the right variety can depend on your available space, the look you want to achieve, and your home’s environment. While general care is similar, some cultivars like ‘Dallas’ are known to be slightly more tolerant of lower humidity.

When to Repot

Preparing for Repotting

• Water the plant a day or two before repotting. Moist soil clings to the roots better and makes removal easier.
• Choose a new pot that is 1-2 inches (2.5-5 cm) larger in diameter than the current pot. Ensure the new pot has adequate drainage holes.
• Prepare your fresh potting mix. Use a well-draining soil mix suitable for ferns, such as a combination of potting soil, peat moss or coco coir, and perlite or vermiculite.

The Repotting Process

1. Add a layer (1-2 inches) of fresh potting mix to the bottom of the new pot.
2. Carefully remove the Boston Fern from its current pot. You may need to gently squeeze the pot or run a knife around the inside edge to loosen it. Support the base of the plant and try to preserve as much of the root ball as possible.
3. Inspect the roots. If the plant is root-bound, gently loosen the circling roots with your fingers. Trim any tangled, dead, or damaged root sections with clean, sharp scissors.
4. Place the fern in the new pot, ensuring the top of the root ball is about an inch below the rim of the container to allow for watering.
5. Fill in around the root ball with more fresh potting mix, gently pressing down to eliminate large air pockets. Do not pack too tightly.
6. Water the plant thoroughly after repotting, allowing excess water to drain completely.
7. Place the repotted fern back in its usual location, avoiding direct sunlight for a few days to allow it to recover.

Dividing Boston Ferns

If your Boston Fern has become too large, or you wish to propagate it, consider dividing it during the repotting process.

• Gently remove the plant from its pot and lay it on its side.
• Using a sharp, clean knife or spade, carefully cut or pull the root ball into two or more sections. Ensure each division has a healthy portion of roots and fronds.
• Repot each division into an appropriately sized pot with fresh potting soil, following the repotting steps above.

Why and When to Prune

Pruning Boston Ferns is essential for maintaining their shape, promoting healthy and vigorous growth, and removing any dead, damaged, or unsightly fronds. Regular pruning also helps improve air circulation, which can prevent pests and diseases.

• Routine trimming of discolored or dead foliage can be done at any time of the year.
• More significant or severe pruning is best done in spring or summer, ideally during repotting when the plant is in its active growth phase.

Pruning Techniques

• Tools: Use clean, sharp pruning shears, scissors, or a knife to make clean cuts and prevent the spread of diseases.
• Removing Fronds: Cut off dead, brown, yellowed, or irregularly shaped fronds at their base, as close to the soil line or the main part of the plant as possible.
• Shaping: Trim side fronds to maintain the plant’s desired shape and control its size. You can also prune runners (stolons) if they become too long or unsightly.- Avoid: Do not cut the top of the plant or remove all the foliage at once. As a general rule, do not remove more than one-third of the plant’s total foliage at a single pruning session.

Encouraging New Growth

Tips for Successful Pruning

• Prune during the active growing season (spring and summer) for the quickest recovery and best results.
• Monitor the plant closely after pruning and provide optimal care (light, water, humidity) to support new growth.
• Be patient; it may take some time for the plant to fully recover and produce substantial new growth after a significant pruning.

Methods of Propagation

Propagating by Division

This is best done during spring repotting.

For a step-by-step overview of the method, see our plant division guide.

1. Carefully remove the parent fern from its pot.
2. Gently separate or cut the root ball into smaller sections using a sterilized sharp knife or by hand if the clumps are loose.
3. Ensure each division has a good portion of healthy roots and several fronds attached.
4. Repot each division into an appropriately sized pot using a fresh, well-draining potting mix suitable for ferns.
5. Water thoroughly after repotting and place the new plants in a location with bright, indirect light and high humidity. Keep the soil consistently moist while they establish.

Propagating from Plantlets (Offsets/Runners)

Boston Ferns often produce runners (stolons) that develop small plantlets at their tips or along their length.

1. Look for plantlets that have started to develop their own small roots. These often form where the runners touch the soil.
2. Once a plantlet has a few small roots (at least 1/2 inch long), you can carefully detach it from the parent runner using clean scissors or a knife.
3. Pot the plantlet in a small pot filled with moist potting mix. You can also pin a runner with an unrooted plantlet down onto the surface of a pot of soil to encourage rooting before detaching.
4. Keep the newly potted plantlet warm and humid (e.g., by covering it loosely with a plastic bag or placing it in a propagator) and the soil consistently moist.

Propagating from Spores

This method is more complex and time-consuming but can be a rewarding experience.

1. Collect spores from the underside of mature fronds. Look for sori that are dark brown and powdery. Place a frond piece, sori-side down, on a sheet of white paper in a dry place for a day or two; the spores will fall onto the paper.
2. Prepare a sterile, shallow tray or pot with a fine, moist, sterile seed-starting mix (e.g., peat moss mixed with perlite).
3. Sow the spores thinly on the surface of the mix. Do not cover them with soil.
4. Cover the container with clear plastic wrap or a transparent lid to maintain high humidity.
5. Place in a warm spot with bright, indirect light. Avoid direct sun.
6. Keep the soil consistently moist by misting or watering from the bottom. Germination can take several weeks to a few months. You’ll first see a green, moss-like growth (the prothalli or gametophyte stage).
7. Once tiny fern fronds (sporophytes) develop from the prothalli and are large enough to handle, carefully transplant them into individual small pots.

Pests That May Affect Boston Ferns

The lush, dense growth of a Boston Fern makes it an attractive home for several common pests. High humidity can deter some, but consistent monitoring is crucial for keeping your plant healthy.

• Spider Mites - The most prevalent pest for indoor Boston Ferns, especially in homes with dry winter air. You’ll notice fine webbing and a generally lackluster, dusty look to the fronds.
• Fungus Gnats - These small, dark flies are attracted to the consistently moist soil that Boston Ferns crave. Their larvae live in the top layer of soil and can damage the fern’s fine root system.
• Mealybugs - Check for these white, waxy insects in the dense crown of the plant and along the stems. They suck plant sap and cause weakness and distorted growth.
• Scale Insects - These appear as hard, brown bumps on the stems and undersides of fronds. They can be difficult to remove once established.
• Whiteflies – Tiny, moth-like insects that fly up in a cloud when the plant is disturbed. They cluster on the undersides of leaves to suck sap, leading to yellowing and sticky residue. Use yellow sticky traps and insecticidal soap to control them.

Promptly isolate any infested fern and treat thoroughly with a horticultural soap or neem oil, ensuring you get full coverage deep into the plant’s crown.

Outdoor Pest Concerns

When kept on a porch or in a hanging basket outdoors, Boston Ferns can attract other pests:

• Slugs & Snails - These will chew on the tender fronds, leaving ragged edges, particularly in damp and shady locations.
• Caterpillars - Can cause significant chewing damage to the foliage. They can be removed by hand.

Troubleshooting Boston Fern Issues

Boston Ferns are famously finicky indoors, and their problems are almost always a cry for more humidity or a change in watering habits.

• Brown, Crispy Edges - This is the classic symptom of low humidity. The air is simply too dry for the fern’s delicate fronds. Increase humidity by misting, using a pebble tray, or running a humidifier.
• Leaf Drop - A stressed Boston Fern will shed its tiny leaflets everywhere. This is its primary response to being underwatered or experiencing a sudden environmental shock like a cold draft or a move.
• Yellowing Leaves - This typically points to a watering issue. Check the soil: if it’s soggy, you’re overwatering; if it’s bone dry, you’re underwatering. Some yellowing of the oldest, innermost fronds is a normal part of the plant’s life cycle.
• Wilting & Drooping - Usually means the plant is extremely thirsty. However, if the soil is already moist and the plant is wilting, it’s a symptom of root rot. Damaged roots can’t absorb water, leading to dehydration symptoms even in wet soil.
• Pale or Faded Leaves - If the fronds look washed-out and pale green, the fern is likely receiving too much direct sunlight, which scorches its leaves. Move it to a spot with bright, indirect light.
• Leggy Growth - Long, sparse fronds indicate the plant is not getting enough light. While they don’t want direct sun, they still need a good amount of bright, ambient light to remain full and lush.
• Sunburn or Leaf Scorch – Appears as large, bleached, white, or crispy brown patches on leaves exposed to too much direct sunlight. This is damage from intense light and heat, not a disease.
• Nutrient Deficiency – Can manifest as slow or stunted growth, pale or yellowing leaves, and a general lack of vigor. It indicates the plant has exhausted the available nutrients in its soil and requires feeding with a balanced fertilizer.

Showcasing Your Fern

Boston ferns are versatile and their lush, arching fronds can beautifully enhance various indoor and (in suitable climates) outdoor spaces. Here are some creative display ideas:

• Hanging Baskets: This is a classic way to display Boston ferns, allowing their graceful fronds to cascade downwards. Hang them near a window with bright, indirect light, or in a shaded spot on a porch or patio.
• Plant Stands: Elevate your Boston fern by placing it on a plant stand of varying height. This not only adds a vertical element to your decor but also allows the fern’s fronds to create an eye-catching focal point without taking up floor space directly.
• Shelves and Bookcases: Incorporate Boston ferns into your home decor by placing them on shelves, mantels, or bookcases. Their vibrant green foliage can add a touch of nature, soften lines, and fill empty spaces.
• Grouping with Other Plants: Create a mini indoor jungle or a lush plant grouping by pairing your Boston fern with other plants that have similar light and humidity requirements. This can include other fern varieties, pothos, peace lilies, or calatheas.
• Decorative Containers: Choose a decorative pot or planter that complements your interior design style. Materials like ceramic, terracotta (though it dries out faster), or woven baskets (with a liner) can add an extra layer of visual interest.
• Wall-mounted Planters: For a unique and space-saving display, consider mounting your Boston fern in a suitable wall-mounted planter. This can contribute to a living wall effect and bring life to an otherwise empty vertical space.
• Table Centerpiece: A well-maintained Boston fern in an attractive container can serve as a stunning table centerpiece for a dining table, coffee table, or console, adding natural elegance.
• Porch or Patio Accent: In appropriate climates (zones 10-12), Boston ferns make beautiful additions to shaded porches, patios, or verandas, often paired with other shade-loving annuals or perennials.

Remember to always provide your Boston fern with the appropriate light, humidity, and watering conditions, regardless of the display method you choose.

Expert Advice for Thriving Ferns

To ensure your Boston fern thrives indoors and maintains its lush, vibrant appearance, follow these expert tips:

• Consistent Indirect Sunlight: Choose an indoor location that receives consistent bright, indirect light, such as near an east-facing window or a few feet from a south or west-facing window with sheer curtains. Avoid direct sunlight, which can scorch the fronds.
• Maximize Humidity: Boston ferns crave high humidity. Mist your fern daily with room-temperature water. Place it in a naturally humid room like a well-lit bathroom or kitchen. Alternatively, set the pot on a tray of pebbles filled with water (ensure the pot doesn’t sit in the water) or use a room humidifier nearby.
• Prune Regularly: Trim away any browning, yellowing, or dead fronds at their base promptly. This not only keeps the plant looking tidy but also encourages new growth and improves air circulation.
• Careful Watering – Avoid Extremes: Keep the soil consistently moist, but never soggy. For precise moisture monitoring, consider using a moisture meter to check deeper soil levels. The top inch should feel slightly dry before watering again. Ensure the pot has good drainage to prevent root rot. Avoid letting the plant dry out completely.
• Fertilize During Growth Season: Feed your Boston fern with a balanced, water-soluble houseplant fertilizer, diluted to half-strength, every 2-4 weeks during the spring and summer. Do not fertilize during fall and winter when growth slows.
• Avoid Drafts and Temperature Swings: Keep your fern away from cold drafts from windows or doors, and also away from direct heat sources like radiators or vents. Stable temperatures are preferred.
• Rotate for Even Growth: Periodically rotate your fern to ensure all sides receive adequate light, promoting even growth and preventing a lopsided shape.
• Use Quality Water: If your tap water is hard or heavily chlorinated, consider using filtered, distilled, or rainwater, or let tap water sit out for 24 hours before use.

Enjoying Your Boston Fern

In conclusion, Boston ferns are a classic and beloved houseplant, admired for their graceful, arching fronds and lush green foliage. While they do require a bit more attention to their environmental needs-particularly humidity and consistent moisture-than some other houseplants, the tropical ambiance and air-purifying qualities they bring indoors make them well worth the effort.

By providing the proper growing conditions, including bright indirect light, high humidity, warm temperatures, and consistently moist soil, your Boston fern can thrive for many years. Addressing common issues like pests, diseases, and watering imbalances promptly by following the care tips in this guide will help maintain its health and beauty. Experiment with different display methods to highlight this plant’s stunning form.

With the proper care outlined in this comprehensive indoor growing guide, you can keep your Boston fern looking healthy, vibrant, and beautiful, transforming any indoor space with a touch of the tropics and a breath of fresh air.

How often should I water my Boston fern?

Can Boston ferns grow in low light?

How do I increase humidity for my Boston fern?

How do I propagate a Boston fern?

Are Boston ferns toxic to pets?

How do I prevent root rot in my Boston fern?

How often should I fertilize my Boston fern?