Giant Swordfern
Nephrolepis biserrata
The Giant Swordfern (Nephrolepis biserrata) is a lush, tropical fern known for its impressive fronds and resilience. Native to tropical regions, it adds a vibrant touch to indoor and outdoor spaces, making it a popular choice among plant enthusiasts.
Everything it needs
9 essentials at a glance
Watering
Water the Giant Swordfern when the top inch of soil feels dry.
During the growing season (spring and summer), water more frequently, about once a week, ensuring the soil remains consistently moist but not soggy. In fall and winter, reduce watering to every 10-14 days. Signs of over-watering include yellowing fronds and root rot, while under-watering can cause browning leaf tips and wilting.
Light
The Giant Swordfern thrives in partial shade to full shade, ideally receiving 4-6 hours of indirect sunlight daily.
Direct sunlight can scorch the leaves, so place it in a location where it is protected from harsh afternoon sun. It can tolerate low light conditions but may grow slower and appear less vibrant.
Soil
This fern prefers a well-draining, rich organic potting mix with a pH range of 5.5 to 7.0.
A mixture of peat, pine bark, and perlite is ideal for good drainage and aeration. Ensure the pot has drainage holes to prevent water accumulation.
Humidity
Giant Swordfern enjoys high humidity levels of 50-70%.
To increase humidity, consider misting the fronds regularly, placing a humidifier nearby, or setting the pot on a tray filled with water and pebbles. Signs of low humidity stress include browning leaf tips and curling fronds.
Temperature
The ideal temperature range for the Giant Swordfern is between 60-75°F (15-24°C).
It is hardy in USDA zones 10-12 and can tolerate brief periods of cooler temperatures but should be protected from frost. In extreme heat, ensure adequate moisture to prevent stress.
Fertilizing
Use a balanced liquid fertilizer with an NPK ratio of 20-20-20, diluted to half strength.
Fertilize every 4-6 weeks during the growing season and avoid fertilizing in winter. Signs of nutrient deficiency include yellowing leaves, stunted growth, and poor frond development.
Pruning
Prune the Giant Swordfern in early spring to remove any dead or damaged fronds.
Use clean, sharp scissors or pruning shears. Deadheading is not necessary, but removing spent fronds encourages new growth and improves the plant's appearance.
Repotting
Repot the Giant Swordfern every 2-3 years or when it becomes root-bound, indicated by roots growing out of the drainage holes.
Choose a pot that is 1-2 inches larger in diameter. Carefully remove the plant, refresh the soil, and replant, ensuring the crown is level with the soil surface.
Propagation
Giant Swordfern can be propagated through division or spores.
To divide, carefully remove the plant from its pot and separate the root ball into sections, ensuring each section has roots and fronds. Replant in fresh soil. For spore propagation, collect spores from mature fronds, sow them on a moist growing medium, and keep them in a humid environment until they germinate, typically in spring.
When it's unhappy
Yellow leaves
Why it happens
This can be caused by over-watering or insufficient light.
How to fix it
Adjust watering frequency and ensure the plant receives adequate indirect light.
Browning leaf tips
Why it happens
Low humidity levels or underwatering can lead to this issue.
How to fix it
Increase humidity through misting or a humidifier and adjust watering habits.
Wilting fronds
Why it happens
Under-watering or root rot from over-watering can cause wilting.
How to fix it
Check soil moisture and adjust watering accordingly, ensuring proper drainage.
Pests (e.g., spider mites, aphids)
Why it happens
Dry conditions can attract pests.
How to fix it
Increase humidity and treat with insecticidal soap or neem oil as needed.
Slow growth
Why it happens
Insufficient light or nutrient deficiency can hinder growth.
How to fix it
Ensure adequate light and fertilize regularly during the growing season.
Care through the year
Spring
In spring, increase watering frequency as the plant begins to grow actively. Fertilize every 4-6 weeks to encourage new frond development.
Summer
During summer, maintain consistent moisture and humidity levels. Monitor for pests and provide shade from harsh afternoon sun to prevent leaf scorch.
Fall
In fall, gradually reduce watering as growth slows. Continue to monitor humidity levels and prepare for cooler temperatures.
Winter
In winter, reduce watering to every 10-14 days and avoid fertilizing. Keep the plant in a warm, humid environment to prevent stress.
Toxicity & Safety
The Giant Swordfern is non-toxic to pets (cats and dogs) and children. It is safe to have around your home without concern for ingestion.
Good to know
Why are my Giant Swordfern leaves turning yellow?
Yellowing leaves on your Giant Swordfern can indicate over-watering or insufficient light. Check the soil moisture and adjust your watering schedule while ensuring the plant receives adequate indirect sunlight.
How often should I water my Giant Swordfern?
Water your Giant Swordfern when the top inch of soil feels dry, typically once a week during the growing season and every 10-14 days in winter. Ensure the soil remains moist but not soggy.
What humidity level is best for Giant Swordfern?
Giant Swordfern thrives in humidity levels of 50-70%. To maintain this, mist the fronds regularly or use a humidifier, especially in dry indoor environments.
How do I propagate my Giant Swordfern?
You can propagate Giant Swordfern through division or spores. For division, separate the root ball into sections and replant, or collect and sow spores on a moist medium for germination.
When should I repot my Giant Swordfern?
Repot your Giant Swordfern every 2-3 years or when it becomes root-bound. Look for roots growing out of the drainage holes as a sign it needs repotting.
What type of fertilizer is best for Giant Swordfern?
Use a balanced liquid fertilizer with an NPK ratio of 20-20-20, diluted to half strength, every 4-6 weeks during the growing season for optimal growth.
Can Giant Swordfern tolerate low light conditions?
Yes, Giant Swordfern can tolerate low light but may grow slower and appear less vibrant. It thrives best in partial to full shade with indirect sunlight.
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