Caring for sword ferns — all about the popular fern

The sword fern (Nephrolepis exaltata and Nephrolepis cordifolia) is probably one of the most popular ferns with its pinnate leaves. The care and the demands on the location require a bit of finesse. In their homeland, the green plants can be found in shady places under trees and in crevices in rocks, sometimes they also grow as epiphytes. The needs of the earth, the light and the temperature are corresponding. If the Nephrolepis, which we cultivate as a room fern, feels comfortable, it forms long fronds and the space on the windowsill becomes too small. Large specimens are predestined for flower stands, pillars and hanging baskets.

Worth knowing LocationCare Watering FertilizingRepottingSpecies Pests & Diseases FAQ

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Worth knowing about the sword fern

Botanical name: Nephrolepis exaltata, Nephrolepis cordifolia

Other names: sword fern, fern, kidney scale fern

Use: Indoor plants, interior greening, room climate plants, ornamental foliage plants, conservatory plants, solitary plants, traffic light plants, terrariums, epiphyte stems

Origin: tropical and subtropical regions in Southeast Asia and South America, Australia

Special features: The popular green plant effectively cleans the air of pollutants such as formaldehyde and solvents. Above all, high humidity and no direct sunlight are important, otherwise the leaf will suffer. The houseplant is suitable for the bathroom.

In which location does sword fern feel most comfortable?

The sword fern prefers a semi-shady location indoors. The indoor fern does not tolerate blazing sun, drafts and dark places. A place facing east or west without direct contact to radiators is ideal. Nephrolepis prefers temperatures above 20 degrees Celsius all year round. From the end of May, the houseplant can be protected from rain and intense sun in the garden. Make sure you get used to the outdoor conditions step by step, otherwise unsightly burns will result. Clear the plant from the garden or balcony back into the house by September at the latest, as cool nighttime temperatures are harmful. Being outdoors often promotes vitality and the indoor plants grow well and develop splendidly after the summer.

Our care tip: direct sunlight burns the fronds. The species can often be found in the herb and shrub layer at its home location. Only part of the UV radiation reaches the plants here. However, it is important to know that there is not enough light in shady locations in the room. Plant lamps can help to improve conditions.

How do I properly care for my sword fern?

Nephrolepis thrive best in a bright location and at a constant temperature. Within a few years, the green plants develop into stately plants. Important in the care are the even soil moisture and humidity. The fern comes from tropical areas, so when it is dry, the leaves drop quickly. Yellow or brown shoots are cut off, but regular pruning is not necessary. For wellness, you can rinse off the fern once a month in the shower with a gentle jet.

Our gardening tip: Fern care includes regular spraying with a spray bottle. Especially in winter, the indoor ferns thrive better with this measure. Wet the fronds regularly with low-lime, tempered water.

How do I water my sword fern properly?

The popular houseplant always needs sufficient moisture. If the bale is too dry, the indoor fern quickly develops yellow leaves or even leaf fall. But it is also important that waterlogging never occurs. It is therefore advisable to pour off the water that is still in the saucer 15 minutes after watering. How often you have to water depends largely on the temperature and the volume of the soil. As a guideline, water every 2 to 3 days. New plants often require less water than fully rooted specimens.

Note: You are welcome to dip the fern once a week. Here you place the houseplant in a bucket filled with water and immerse the plant until no more air bubbles rise. As a result, the root ball is evenly moist and the houseplant is well cared for.

How do I fertilize my sword fern properly?

A special green plant fertilizer is ideal for fertilizing Nephrolepis. This contains important growth and vital substances and thus helps the plant to form new fronds. Fertilize the green plant weekly from March to October and once a month in winter. Make sure that the soil is not too dry when fertilizing, otherwise damage to the roots can occur. Fertilizing with fertilizer sticks is easy to handle. With this convenient long-term fertilization, your plant is supplied with all the necessary nutrients, minerals and trace elements for 3 months.

How do I repot my sword fern?

Depending on the size, it is advisable to repot your fern every 1 to 2 years, as the old substrate is rooted through and a larger planter makes maintenance easier. For transplanting, use good quality green potting soil with a pH of 5.5 to 6. This potting soil is loose, structurally stable and specially tailored to the needs of the species. If possible, transplant in the spring and choose a pot that is a few centimeters larger than the previous container. For better drainage, put a layer of expanded clay on the bottom of the pot. It is important that you do not plant the fern too deep in the new substrate.

Our tip: Avoid repotting in winter. With less light and heating air, there shouldn’t be any major changes for the fern.

Which sword fern types and varieties are there?

Nephrolepis are a genus of ferns that have been represented worldwide with almost 20 species for millions of years. The representatives known today as room ferns can be cultivated both terrestrially and epiphytically. This means they can either grow in substrate or live as epiphytes on logs. The latter way of life is a little more complicated to practice under normal indoor conditions. In horticultural culture are mainly Nephrolepis exaltata and Nephrolepis cordifolia. Basically, the different species differ in the length of the fronds, the leaf shape and leaf color.

Nephrolepis cordifolia

  • Natural form of the sword fern
  • narrow, simply pinnate fronds
  • slightly overhanging
  • 50 to 60 cm in length

Nephrolepis exaltata

  • broad pinnate or compound fronds
  • partially curled leaves
  • upright to overhanging growth

60 to 80 cm in length. Common varieties of Nephrolepis exaltata are ‘Bostoniensis’ and ‘Green Lady’.

What pests and diseases can the sword fern get?

Basically, the popular green plants are insensitive in the optimal location. Too much sun will result in brown leaves. If the foliage is yellow, there may be a lack of fertilizer or the plant has not had enough water. At lower temperatures, the exotic plants also suffer. The following pests can occur:

spider mites

An infestation with spider mites can occur, especially when the air is dry in winter. The foliage has silvery dots on the upper side and webs are visible on the underside of the leaves. It is usually sufficient to spray the plant with water and treat it with a plant strengthener. Apply this tonic several times as described. Above all, the natural plant extracts contained contribute to the vitalization of the plant. Improve the conditions, especially during the winter months, and spray the fern regularly with lime-free water.

scale insects

Brown, slightly convex knobs can be found in the leaf axils of Nephrolepis exaltata and Nephrolepis cordifolia. The scale insects are safely hidden under these protective shields and are therefore difficult to combat. As soon as you discover the infestation, you should wipe off the scale insects or cut back the houseplant. The pests can be controlled biologically with oil-based agents. It is important that the application is carried out several times.

FAQ — Frequently Asked Questions

How is sword fern propagated?

As with all fern species, so-called spores form on older plants. Located on the underside of the leaf, these seed deposits are clustered capsules. The green or brownish spots are often perceived as diseases or pests. When the capsules are ripe, they dry and release the spores they contain. Depending on the genus, a capsule can contain up to 500 spores. The spores can be felt and seen as fine dust. With proper care and optimal ambient temperature, the spores germinate and after a year a small fern may have developed. Partially, the propagation also takes place by offshoots.