Complete Guide To Button Fern Care and Growth

Quick Overview

The Button Fern (Pellaea rotundifolia) is a delightful and distinctive fern, cherished for its unique appearance. It features gracefully arching fronds adorned with small, round, leathery, button-like leaflets (pinnae) of a deep green color. Native to the cool, moist forests and rocky crevices of New Zealand and parts of Australia, this fern brings a touch of woodland charm indoors.

Typically a low-growing plant, the Button Fern forms a compact clump, making it an excellent choice for smaller spaces, terrariums, or as an accent plant. While it shares the fern family’s love for humidity and consistent moisture, it can be slightly more tolerant of drier conditions than some of its relatives, though it still thrives best with ample humidity. It is non-toxic to pets.

Ideal Light for Button Fern

Button Ferns perform best in medium to bright indirect light. They are accustomed to the dappled sunlight of a forest floor, so replicating these conditions indoors is key. An east-facing window that provides gentle morning sun is often ideal. They can also thrive near a north-facing window or a few feet away from a west- or south-facing window where the light is filtered by sheer curtains or shaded by other objects.

Avoid placing your Button Fern in direct, intense sunlight, as this can easily scorch its delicate fronds, leading to brown, crispy patches.

Low Light Tolerance and Signs of Issues

While Button Ferns can tolerate lower light conditions for some time, prolonged exposure to insufficient light will result in slower, sparser growth, and the fronds may appear less vibrant. If the plant is getting too much light, you might notice faded or scorched leaves.

• Too Little Light: Leggy growth, pale fronds, slow development.
• Too Much Light: Scorched or brown leaf tips/patches, faded leaf color.

Watering Needs

Watering Frequency

• Growing Season (Spring to Early Fall): Water when the top 0.5 to 1 inch of soil feels slightly dry to the touch. This might mean watering once or twice a week, depending on your home’s temperature, humidity, light exposure, and pot size.
• Dormant Season (Late Fall to Winter): Reduce watering frequency slightly as the plant’s growth slows. Allow the soil to dry out a bit more between waterings, but never let it dry out completely.

Always use room-temperature water to avoid shocking the roots. Water thoroughly until water drains from the bottom of the pot, then discard any excess water from the saucer.

Signs of Improper Watering

• Overwatering: Yellowing fronds (especially lower ones), wilting despite moist soil, mushy stem bases, a musty smell from the soil (indicating root rot).
• Underwatering: Fronds turning brown and crispy, wilting, dry and brittle leaflets, slow growth.

Ideal Soil Characteristics

Button Ferns thrive in a well-draining, yet moisture-retentive potting mix that is rich in organic matter. The soil should allow for good aeration to the roots while holding enough moisture to keep the fern happy. A slightly acidic to neutral pH (around 5.5-7.0) is generally preferred.

The ideal soil should:

• Provide excellent drainage to prevent sogginess.
• Retain adequate moisture.
• Be light and airy, not heavy or prone to compaction.

DIY Soil Mix Recipe

A good homemade potting mix for Button Ferns can be created using:

• 2 parts peat moss or coco coir (for moisture retention and acidity)
• 1 part perlite or coarse sand (for aeration and drainage)
• 1 part quality potting soil or compost (for nutrients and structure)
• Optional: A small amount of horticultural charcoal can help keep the soil fresh.

Mix these components thoroughly. This blend will offer the right balance for your fern.

Pre-Made Potting Mix Options

Do Button Ferns Need Fertilizer?

Type and Frequency

• Use a balanced, water-soluble liquid houseplant fertilizer (e.g., with an NPK ratio like 10-10-10 or 20-20-20).
• Dilute the fertilizer to half or even quarter the strength recommended on the product label. Ferns, in general, have sensitive roots that can be easily burned by full-strength fertilizer.
• Fertilize once a month during the spring and summer months.
• Do not fertilize in the fall and winter when the plant’s growth naturally slows down.

Application Tips

• Always water the plant thoroughly before applying fertilizer. Fertilizing dry soil can damage the roots.
• Avoid over-fertilizing. Signs of excess fertilizer can include burnt leaf tips or edges, or a white, crusty buildup on the soil surface. If this occurs, flush the soil with plenty of water.

Ideal Temperature Range

Button Ferns prefer average to cool room temperatures, typical of most homes.

• Ideal Range: 60–75°F (15–24°C). They appreciate consistency and are sensitive to abrupt temperature changes.

Temperature Stress Factors

• Cold Sensitivity: Avoid exposing the plant to temperatures below 50°F (10°C) for prolonged periods, as this can cause cold damage, leading to browning or dropping fronds.
• Avoid Drafts: Keep your Button Fern away from cold drafts from windows, doors, or air conditioning vents. Sudden chills can stress the plant.
• Proximity to Heat Sources: Similarly, do not place it too close to direct heat sources such as radiators, fireplaces, or heating vents, as this can dry out the plant rapidly and scorch the foliage.

Importance of High Humidity

Like most ferns, Button Ferns are native to humid environments and thrive when humidity levels are high.

• Ideal Humidity: 50% or higher. Low humidity is one of the most common reasons Button Ferns struggle indoors, leading to brown, crispy fronds.

How to Increase Indoor Humidity

If the air in your home is dry, especially during winter months when heating systems are active, consider these methods to boost humidity for your Button Fern:

• Misting: Mist the plant’s fronds daily with room-temperature water. This provides a temporary humidity boost.
• Pebble Tray: Place the pot on a tray filled with pebbles and a small amount of water. Ensure the bottom of the pot is not sitting directly in the water. As the water evaporates, it will increase humidity around the plant.
• Humidifier: Using a small room humidifier near your Button Fern is one of the most effective ways to maintain consistent high humidity.
• Grouping Plants: Cluster your Button Fern with other houseplants. The collective transpiration from plants helps create a more humid microclimate.
• Terrariums: Button Ferns are excellent candidates for enclosed or semi-enclosed terrariums, which naturally maintain high humidity levels.
• Location: Placing your fern in a naturally more humid room, such as a well-lit bathroom or kitchen, can also be beneficial.

Signs of Low Humidity

• Frond tips and edges turning brown and crispy.
• Leaflets (pinnae) may shrivel or drop.
• Overall dull appearance of the foliage.

Do Button Ferns Flower?

Spore Production

Spores are tiny, single-celled reproductive units. On Button Ferns, these spores are produced in structures called sori (singular: sorus). The sori are typically found on the undersides of the mature leaflets (pinnae), often appearing as small, brownish clusters or lines along the edges. These are sometimes mistaken for pests or diseases by those unfamiliar with fern anatomy.

When the spores are mature, the sori will release them into the air. If a spore lands in a suitable moist and shaded environment, it can germinate and begin the fern’s complex life cycle, eventually developing into a new fern plant. Propagating ferns from spores is possible but can be a challenging and lengthy process for the home gardener.

Understanding Pellaea rotundifolia

Pellaea rotundifolia, the Button Fern, is a fairly distinct species without a wide array of commonly cultivated varieties or cultivars that drastically differ in appearance from the standard form. Its charm lies in its consistent and unique characteristics:

• Leaflets (Pinnae): The most notable feature is its nearly round, button-like leaflets, which are dark green, leathery in texture, and alternately arranged along the wiry, dark stems (rachis).
• Fronds: The fronds are pinnately compound, typically arching or spreading, and can reach lengths of up to 12-18 inches.
• Growth Habit: It forms a low-growing, spreading clump, originating from a creeping rhizome.

While other species exist within the Pellaea genus (cliff brake ferns), such as Pellaea falcata (Sickle Fern) which has more elongated, sickle-shaped pinnae, Pellaea rotundifolia is specifically recognized by its characteristically round leaflets. When purchasing a Button Fern, you are generally getting this specific species.

When to Repot

Button Ferns have a relatively slow to moderate growth rate and do not require frequent repotting. They prefer to be slightly root-bound.

• Frequency: Typically, repot every 2-3 years, or when the plant shows clear signs of having outgrown its current container.
• Signs it’s time to repot:
  • Roots are visibly growing out of the drainage holes.
  • The plant dries out much more quickly than usual, requiring very frequent watering.
  • Growth has significantly slowed or stalled, even during the growing season.
  • The plant appears overcrowded in its pot, or water sits on top of the soil without draining.

The best time to repot is during the spring, as the plant is entering its active growth period.

How to Repot

1. Choose a New Pot: Select a new pot that is only one size larger (e.g., about 1-2 inches wider in diameter) than the current one. Using a pot that is too large can lead to the soil staying wet for too long, increasing the risk of root rot. Ensure the new pot has adequate drainage holes.
2. Prepare Potting Mix: Use fresh, well-aerating potting mix suitable for ferns (as detailed in the Soil section).
3. Remove the Plant: Gently remove the Button Fern from its old pot. You may need to tap the sides of the pot or carefully slide a thin tool around the inside edge to loosen it. Support the base of the plant and try to keep the root ball as intact as possible.
4. Inspect Roots: Examine the root ball. If the roots are tightly circling (root-bound), gently try to loosen them with your fingers. Trim away any roots that appear mushy, dark brown/black, or have a foul odor, as these are signs of rot. Use clean, sharp scissors for trimming.
5. Pot Up: Add a layer of fresh potting mix to the bottom of the new pot. Position the plant in the center of the new pot, ensuring the top of the root ball is at approximately the same level as it was in the old pot, or about an inch below the rim of the new pot to allow space for watering. Fill in around the root ball with more fresh potting mix, gently firming it down to eliminate large air pockets, but avoid packing it too tightly.
6. Water Thoroughly: After repotting, water the plant thoroughly to help settle the soil and provide initial moisture. Allow excess water to drain completely.
7. Aftercare: Place the repotted Button Fern back in its usual location with bright, indirect light and high humidity. It may take a few weeks for the plant to adjust. Avoid fertilizing for at least a month after repotting.

Why and When to Prune

Pruning Button Ferns is generally minimal and primarily focused on maintaining the plant’s appearance and health by removing old or damaged foliage.

• Removing Dead or Damaged Fronds: Trim off any fronds that are entirely brown, yellow, crispy, or show signs of disease or pest damage. This helps improve air circulation and directs the plant’s energy towards healthy growth. This can be done at any time of year as needed.
• Shaping: Button Ferns have a naturally attractive arching or spreading habit, so extensive shaping is rarely necessary. If some fronds are growing erratically or making the plant look untidy, you can selectively prune them.

Use clean, sharp scissors or small pruning snips to make cuts. Cut the unwanted fronds off at their base, as close to the soil line or the rhizome as possible.

Encouraging New Growth

Methods of Propagation

Propagating by Division

This method is best performed when repotting a mature, well-established Button Fern that has formed multiple growing points or a dense clump.

1. Prepare: Gather your materials: a clean, sharp knife or pair of snips, new pots, and fresh potting mix suitable for ferns.
2. Remove from Pot: Carefully take the parent Button Fern out of its pot. Gently shake off excess soil to get a better view of the rhizome and root structure.
3. Divide the Rhizome: Identify natural divisions in the rhizome (the thick, often fuzzy, horizontal stem from which fronds and roots grow). Using your clean knife or snips, carefully cut the rhizome into sections. Ensure each section has a healthy portion of the rhizome, several attached fronds, and a good cluster of roots.
4. Pot Up Divisions: Plant each new division into its own appropriately sized pot filled with fresh, moist fern potting mix. Pot them at the same depth they were growing previously.
5. Aftercare: Water the newly potted divisions lightly. Place them in a location with bright, indirect light and high humidity. You can increase humidity by covering the pots loosely with clear plastic bags for a few weeks (ensure some ventilation to prevent mold) or by placing them in a propagator. Keep the soil consistently moist but not soggy while the new plants establish.

Propagating from Spores

This method mimics the natural reproductive cycle of ferns but requires patience and sterile conditions.

1. Collect Spores: Wait until the sori (spore-producing structures) on the undersides of mature fronds turn dark brown and look powdery. Carefully cut a frond with ripe sori and place it, sori-side down, on a clean sheet of white paper in a dry, draft-free place for a day or two. The tiny, dust-like spores will fall onto the paper.
2. Prepare Sowing Medium: Fill a shallow, clean tray or pot (with drainage holes) with a sterile, fine-textured seed-starting mix, often peat-based or a specific fern spore mix. Moisten the mix thoroughly from the bottom or with a fine mist.
3. Sow Spores: Gently tap the paper to distribute the collected spores thinly and evenly over the surface of the moist sowing medium. Do not cover the spores with soil.
4. Maintain Humidity and Light: Cover the container with a clear plastic lid, plastic wrap, or place it inside a clear plastic bag to create a highly humid environment. Position the container in a warm spot (around 70°F/21°C) with bright, indirect light (avoid direct sun).
5. Germination: Keep the sowing medium consistently moist by misting lightly or watering from the bottom as needed. Germination can take several weeks to many months. The first sign of growth will be a green, moss-like film or tiny heart-shaped structures called prothalli (the gametophyte stage).
6. Development of Sporophytes: Fertilization occurs on the prothalli, and eventually, tiny fern fronds (the sporophyte stage, which is the fern plant we recognize) will begin to emerge from them. This can also take several more weeks or months.
7. Transplanting: Once the young fernlets are large enough to handle (typically with a few small fronds), they can be very carefully pricked out and transplanted into individual small pots with fern potting mix. Continue to provide high humidity and gentle care as they mature.

Pests That May Affect Button Ferns

While generally robust, Button Ferns can occasionally be affected by common houseplant pests, particularly if the plant is stressed due to suboptimal growing conditions (like low humidity). Regular inspection, especially of the undersides of fronds and new growth, can help catch infestations early.

• Spider Mites: These tiny arachnids thrive in dry conditions. Signs include fine webbing between fronds or on leaflets, stippling (tiny yellow or brown dots) on the leaflets, and a generally dusty or unhealthy appearance. The small, dense foliage of the Button Fern can make them harder to spot initially.
• Mealybugs: These are small, white, cottony insects that often hide in protected areas such as the base of fronds, in leaf axils (if applicable to fern structure), or along the rhizome. They feed on plant sap, which can lead to stunted growth and sticky honeydew.
• Scale Insects: Scale appear as small, immobile, shell-like bumps, often brown or tan, attached to stems (rachis) or the undersides of leaflets. They also feed on plant sap, weakening the plant over time and potentially causing yellowing or leaf drop.
• Fungus Gnats: These small, dark, mosquito-like flies are attracted to consistently moist soil. While the adult gnats are primarily a nuisance, their larvae, which live in the top layer of soil, can feed on plant roots and tender new growth, especially in young or stressed ferns. Allowing the soil surface to dry slightly more between waterings can help control them.

If pests are detected, isolate the infested plant immediately to prevent them from spreading. Treat promptly with an appropriate method, such as wiping affected areas with alcohol-dipped cotton swabs for mealybugs and scale, or spraying with insecticidal soap or neem oil for more widespread infestations like spider mites. Ensure good air circulation and appropriate humidity to deter pests.

Troubleshooting Button Fern Issues

Button Ferns, while charming, can present a few challenges, mostly related to their need for consistent moisture and high humidity.

• Brown, Crispy Edges or Fronds: This is the most common issue and is almost always a sign of low humidity or underwatering. The air is too dry, or the soil has been allowed to dry out too much. Increase humidity significantly and ensure consistent soil moisture.
• Yellowing Leaves (Fronds): Can be caused by several factors. Overwatering is a primary suspect, leading to root rot where roots can’t function. It can also be due to underwatering (though browning is more common), nutrient deficiencies, or sometimes natural aging of older fronds. Check soil moisture and root health.
• Root Rot: Occurs when the soil is kept too wet or drainage is poor. Roots become mushy, brown/black, and can no longer absorb water or nutrients, leading to wilting, yellowing, and eventual plant death. Prevention is key: use well-draining soil and avoid overwatering.
• Stunted Growth: May result from insufficient light, lack of nutrients (if never fertilized), being severely root-bound, persistent pest problems, or consistently poor environmental conditions (e.g., very low humidity).
• Leaf Drop (Pinnae Falling Off): Severe stress, often from extreme dryness (both soil and air), sudden temperature changes (especially cold drafts), or severe pest infestation can cause the individual “buttons” or entire fronds to drop.
• Pale or Faded Leaves: Can indicate too much direct sunlight, which bleaches the fronds, or sometimes a nutrient deficiency. Ensure the fern is in bright, indirect light.

Addressing these issues typically involves adjusting care routines: improving humidity, ensuring proper watering techniques, providing appropriate light, and checking for pests.

Showcasing Your Button Fern

The Button Fern’s unique texture, compact size, and gracefully arching fronds make it a versatile plant for various indoor displays:

• Terrariums: Its manageable size and love for high humidity make the Button Fern an ideal candidate for enclosed or open terrariums, creating a miniature woodland scene.
• Small Decorative Pots: Placed in an attractive small pot, it can be a charming accent on desks, shelves, windowsills (with filtered light), or bedside tables.
• Hanging Baskets: In a small hanging basket, its arching fronds can cascade gently, allowing its button-like leaflets to be admired from different angles.
• Bathroom or Kitchen Placement: These rooms often have naturally higher humidity levels, which can benefit the Button Fern, provided there is adequate indirect light.
• Groupings with Other Plants: Combine it with other humidity-loving plants like other ferns, Calatheas, or Marantas. This not only creates an attractive, lush display but also helps increase local humidity.
• Underplanting: For larger potted plants, a Button Fern can serve as a lovely, textured “ground cover” at the base, provided the light and moisture conditions are compatible.
• Kokedama or Mounted Displays: For a more artistic approach, Button Ferns can be grown as kokedama (moss balls) or mounted on driftwood or cork bark (requiring very consistent moisture and misting).

When choosing a display method, always prioritize the plant’s need for bright indirect light, high humidity, and consistent moisture.

Expert Advice for Lush Button Ferns

To help your Button Fern flourish and maintain its unique charm, keep these expert tips in mind:

• Humidity is King: This cannot be overstated. Button Ferns crave high humidity (50%+). Consistently mist, use a pebble tray, group with other plants, or invest in a small humidifier, especially in dry indoor environments.
• Consistent Moisture, Not Sogginess: Aim for soil that feels like a well-wrung sponge. Water thoroughly when the top 0.5-1 inch is slightly dry, but never let the pot sit in water.
• Bright, Indirect Light is Ideal: Mimic dappled forest light. Avoid direct sun, which will scorch the fronds, but don’t relegate it to deep shade either.
• Use Well-Draining, Rich Soil: A peat-based mix amended with perlite for drainage works well. Good aeration is important for healthy roots.
• Fertilize Sparingly: Feed only during the growing season (spring/summer) with a heavily diluted liquid fertilizer, no more than once a month.
• Protect from Drafts and Temperature Extremes: Stable, moderate temperatures (60-75°F / 15-24°C) are best. Avoid placing near cold drafts or direct heat sources.
• Gentle Cleaning: If fronds get dusty, gently mist them or carefully wipe with a soft, damp cloth. Avoid leaf shine products.
• Repot Only When Necessary: Button Ferns don’t mind being slightly root-bound. Repot every 2-3 years or when clearly needed, into a pot just one size larger.
• Monitor for Pests Regularly: Check under fronds and around the base for early signs of common houseplant pests.

Enjoying Your Button Fern

The Button Fern (Pellaea rotundifolia) is a truly unique and endearing addition to any houseplant collection, offering distinctive texture and a touch of woodland elegance. While it requires attention to its specific needs, particularly concerning humidity and consistent moisture, the reward is a beautiful, thriving fern that can grace your home for years.

By providing the right balance of bright indirect light, high humidity, appropriate watering, and a suitable soil mix, you can successfully cultivate this charming New Zealand native. Its compact size makes it versatile for various displays, from terrariums to desktops. Remember that patience and observation are key to understanding your Button Fern’s individual requirements in your specific home environment. With a little dedicated care, you can enjoy the lush, button-adorned fronds of this special fern.

Why are the fronds on my Button Fern turning brown and crispy?

Can Button Ferns tolerate low light?

How often should I water my Button Fern?

Is the Button Fern safe for pets?

How do I increase humidity for my Button Fern?