Complete Guide to Asian Sword Fern Care and Growth

Quick Overview

The Asian Sword Fern (Nephrolepis brownii), more famously known as the Kimberly Queen Fern, is a beautiful and robust evergreen fern. It stands out with its upright, narrow, sword-shaped fronds that create a neat, tidy appearance. Unlike its cousin, the Boston Fern, the Asian Sword Fern is less prone to shedding, making it a cleaner choice for an indoor plant.

Native to Asia and Australia, this fern is not only prized for its structural beauty but also for its excellent air-purifying qualities. It’s relatively easy to care for, thriving in conditions that mimic its native forest floor environment.

How much light does an Asian Sword Fern need?

Asian Sword Ferns thrive in bright, indirect light. Think of the dappled sunlight they would receive on a forest floor. An east-facing window that provides gentle morning sun is ideal. They can also do well near a north-facing window or set back from a brighter south or west-facing window.

While they can tolerate lower light conditions, their growth may become leggy. Avoid exposing them to harsh, direct afternoon sun, as it can scorch their delicate fronds, causing them to turn yellow or brown.

Light PRO Tips

How to Water an Asian Sword Fern

Consistent moisture is key for a healthy Asian Sword Fern. The soil should be kept evenly moist, but never waterlogged or soggy, as this can lead to root rot.

A good rule of thumb is to water thoroughly when the top inch of soil feels dry to the touch. During the active growing season (spring and summer), you may need to water more frequently. In the fall and winter, reduce the watering frequency, allowing the soil to dry out a bit more between waterings. Always use room temperature water to avoid shocking the plant’s roots.

Troubleshooting Water Issues

• Yellowing Fronds: Often a sign of overwatering. Ensure the pot has proper drainage and you’re not letting the plant sit in a saucer of water.
• Crispy, Brown Fronds: This typically indicates underwatering. Water the plant deeply and check the soil moisture more regularly.

Best Soil for Asian Sword Ferns

The right soil provides the foundation for a thriving fern. Asian Sword Ferns need a potting mix that is well-draining yet capable of retaining adequate moisture. A high-quality, peat-based potting mix is an excellent choice.

To improve drainage and aeration, you can amend a standard potting mix with ingredients like perlite, orchid bark, or compost. The goal is to create a rich, loamy soil that mimics their natural habitat. A slightly acidic to neutral soil pH is ideal.

How to Feed an Asian Sword Fern

During the growing season (spring through summer), feed your Asian Sword Fern with a balanced, water-soluble fertilizer. Dilute the fertilizer to half the recommended strength to avoid burning the roots.

Apply the fertilizer every 4-6 weeks. There is no need to fertilize during the fall and winter when the plant’s growth naturally slows down. Over-fertilizing can cause a buildup of salts in the soil, which can damage the plant.

Ideal Temperature Range

Asian Sword Ferns prefer average to warm household temperatures, ideally between 60-75°F (16-24°C). They are not frost-tolerant, so if you keep your fern outdoors, be sure to bring it inside before the first frost.

Protect your fern from sudden temperature fluctuations. Keep it away from drafty windows, doors, and air conditioning or heating vents.

Humidity Requirements for Asian Sword Ferns

Like most ferns, the Asian Sword Fern loves high humidity. It thrives in environments with 50% humidity or higher. In most homes, especially during winter when heating systems are running, the air is too dry.

To increase humidity, you can:

• Mist the fronds with water a few times a week.
• Place the pot on a pebble tray filled with water (ensure the pot is not sitting directly in the water).
• Group it with other plants to create a more humid microclimate.
• Use a small room humidifier near the plant.

A bathroom with a bright window is often a perfect location for a humidity-loving fern.

Do Asian Sword Ferns flower?

Pests That May Affect Asian Sword Ferns

The dense, overlapping fronds of the Asian Sword Fern can provide ample hiding spots for common houseplant pests. Its vigorous growth can sometimes mask early infestations, so regular checks are important.

• Spider Mites - These tiny arachnids thrive in low humidity and can quickly cover a fern in fine webbing, causing the fronds to look faded and dusty.
• Mealybugs - Look for white, cottony masses near the crown of the plant and where the fronds meet the soil. They feed on plant sap, leading to weakened growth.
• Scale Insects - These immobile, armored pests look like small brown bumps and typically attach themselves to the fern’s stems (stipes) and the central vein of the fronds.
• Fungus Gnats - The consistently moist soil required by this fern is an ideal habitat for fungus gnat larvae. While adults are a nuisance, a large larval population can damage the root system.
• 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.

When treating, ensure your chosen solution (like insecticidal soap or neem oil) penetrates the dense foliage to reach all hidden pests.

Outdoor Pest Concerns

If grown outdoors on a patio or in the garden, Asian Sword Ferns may also be targeted by:

• Slugs & Snails - These mollusks will chew holes in the tender fronds, especially in damp, shady conditions.
• Caterpillars - Various types of caterpillars may feed on the fern’s foliage, leaving behind chewed edges and droppings.

Troubleshooting Asian Sword Fern Issues

Like its close relatives, the Asian Sword Fern’s health is directly tied to humidity and proper watering. Its problems are almost always a signal that one of these core needs is not being met.

• Brown, Crispy Edges - This is a clear sign that the air is too dry. The Asian Sword Fern needs high humidity. To fix this, mist the plant often, group it with other plants, or use a room humidifier.
• Yellowing Leaves - Can be caused by both overwatering (soggy soil) and underwatering (very dry soil). Check the moisture level an inch deep into the soil to determine the cause. Some yellowing of older, lower fronds is normal.
• Leaf Drop - When this fern gets stressed, particularly from being too dry, it will shed its tiny leaflets, creating a significant mess. It’s a dramatic plea for more consistent watering.
• Wilting & Drooping - This is the fern’s primary sign of thirst. A thorough watering will usually cause it to perk up within a few hours. If the soil is already wet, this could indicate root rot, as damaged roots cannot absorb moisture.
• Stunted Growth - If the fern is not producing new growth during the spring and summer, it may be root-bound and need a larger pot, or it could be lacking in light or nutrients.
• Sunburn or Leaf Scorch - Direct sun can cause fronds to develop bleached, brown, or crispy patches. Move the fern out of harsh sunlight and trim away damaged areas. Provide bright, indirect light for best results.

Propagating Through Division

The easiest and most effective way to propagate an Asian Sword Fern is by division. This is best done in the spring when you are repotting the plant.

1. Carefully remove the fern from its pot.
2. Gently tease the root ball apart with your hands or use a clean, sharp knife to cut it into two or more sections.
3. Ensure that each section has a healthy portion of roots and several fronds.
4. Pot each new division into its own container with fresh, appropriate potting soil.
5. Water the new plants well and keep them in a warm, humid spot out of direct sunlight until they show signs of new growth.

Creative Ways to Display Asian Sword Ferns

The neat, upright habit of the Asian Sword Fern makes it incredibly versatile for home decor. Here are some ideas:

• Floor Plant: In a large, decorative pot, it can serve as a stunning floor plant to fill an empty corner.
• Hanging Basket: While it’s more upright than a Boston Fern, its lush fronds will still create a beautiful cascading effect in a hanging basket.
• On a Stand: Elevating the fern on a plant stand can highlight its graceful, arching fronds.
• Outdoor Containers: On a shaded patio or porch, they look fantastic in containers, either alone or mixed with other shade-loving annuals.

Is the Asian Sword Fern the same as Kimberly Queen Fern?

Is the Asian Sword Fern safe for pets?

Why are the tips of my fern's fronds turning brown?

How often should I repot my Asian Sword Fern?

Can I grow Asian Sword Fern outdoors?