Nephrolepis exaltata

Common name: Sword Fern, Wild Boston Fern, Tuber Ladder Fern, Fishbone Fern, Boston Fern

Family: Lomariopsidaceae

Nephrolepis exaltata

Nephrolepis exaltata

Distribution and habitat: Nephrolepis exaltata ferns grow in jungles in Central and South America where they are shaded by the jungle canopy but receive moisture on a regular basis. Within Nephrolepis exaltata genus there are many varieties, some of them quite small and compact, others quite large. These evergreen terrestrial or epiphytic ferns have short rhizomes and usually wiry spreading runners. It is considered as being a serious invasive plant, forming dense monocultures.

Description: Nephrolepis exaltata has 50–250cm (20-98 inch) long and 6–15cm (2-6 inch) broad in tufted clusters arising from underground rhizomes.  The individual pinnae (leflets) are as much as 2 to 8cm (1-3 inch) long and shallowly toothed, but not further divided. The pinnate vein pattern is also visible on these highly compound leaves. The round sori (clusters of spore-bearing organs) are in two rows near the margins on the underside of the pinnae.
The fronds grow upright at first, then arch gracefully downwards. They grow in lovely arching rosette shaped and spread by runners.

Houseplant care: Nephrolepis exaltata is one of the easiest of the ferns to grow indoors. These ferns need pliantly of space to develop their long fronds. Rotate the plant from time to time to ensure symmetrical growth, but as far as possible leave it undisturbed.

Nephrolepis exaltata ferns do not tolerate dry air. They need high level of humidity provided by regular misting and trays of moist pebbles placed under their pots. Use trepid soft water if possible. Once a week, apply a gentle shower  with trepid water. Leave them in bath to drain before returning them to their usual place.

In some of the extremely feathery forms of Nephrolepis exaltata Bostoniensis some of the fronds of the plant occasionally revers to the original species. Cut out any long, insufficiently segmented fronds as soon as they appear. If permitted to survive, they will take over the plant.

Light: Provide to Nephrolepis exaltata bright light without direct sunlight. If necessary these ferns can tolerate medium light for periods up to four or five weeks.
A good place for Nephrolepis exaltata is in front of an east-facing window or several feet from a west or south facing window.

Temperature: Normal room temperatures are suitable throughout the year. Minimum tolerable temperature is 10°C (50°F). For Nephrolepis exaltata grown at temperatures above 21°C (70°F) increase humidity by standing the pot on a tray of damp pebbles and mist-spraying the foliage daily.

Nephrolepis exaltata may appear totally dead due to frost, it will re-emerge in the spring.

Watering: In summer Nephrolepis exaltata will need lots of water and frequent misting. As long as room temperatures remains above 13°C (55°F), water the plant plentifully as often as necessary to keep the potting mixture thoroughly moist. Do not allow the potting mixture to dry out. In winter this fern will need less water.  If the temperature drops below 13°C (55°F) for more than a day or two, allow the top third of the potting mixture to dry out completely between waterings.
Water hanging baskets ferns by plunging in a bath or bucket of water, to cover the soil surface. Let it to absorb water for 15-30 minute.

Fertilising: Apply standard liquid fertiliser every two weeks to Nephrolepis exaltata actively growing in peat-based potting mixture. Feed actively growing plants that are in soil based mixture about once every four weeks.

Potting and repotting: Use either a standard peat-based potting mixture or a combination of half soil based mixture and half leaf mould. When the roots of Nephrolepis exaltata have filled its current pot, repot in the spring, moving the plant into a pot only one size larger. After maximum convenient pot size has been reached, remove the plant from its pot every spring, carefully trim away some of the outer roots and replace the plant in the same pot, which has been thoroughly cleaned. Add fresh mixture as required.

Gardening: Nephrolepis exaltata requires little maintenance, except to keep it in check from spreading too far and too fast, which it does by way of its underground rhizomes.
Nephrolepis exaltata is killed to the ground by frost but will re-emerge in spring.

Location: Nephrolepis exaltata are easily grown in mild areas in part shade or full shade. Plant them in bright indirect light with no direct sun.

Soil: Nephrolepis exaltata grows well in humus-rich soil. Good drainage is mandatory. Amend heavy clay or sandy soils with organic matter.

Irrigation: Follow a regular watering schedule as these ferns need moist soil and steady high humidity. Water them slowly and deeply, allowing the substrate to dry slightly between waterings. It is best to water early in the day to allow the fronds plenty of time to dry before night time.
Ferns need to be kept consistently moist at all times. They do not however want to be soggy or water logged.
Nephrolepis exaltata is the most drought tolerant of the commonly cultivated ferns, but it thrives only under conditions of high humidity.
Mulches them to help reduce water evaporation in hot or dry weather.

Fertilising: Nephrolepis exaltata thrives best when are added 5-8cm (2-3 inch) of compost or peat moss to the beds each spring or fall. This treatment should suffice and no additional fertilising is require.
Adding controlled release fertiliser on the soil surface should be done at low rates, as recommended on label. Ferns are sensitive to high salt levels, so moderation should be considerate when decide to fertilise them.

Propagation: Nephrolepis exaltata plant is usually propagated by division of the rooted runners, as named cultivars will not produce true spores. Propagate whanever desirable by potting up a new plantlet taken from any point where the tip of a runner has rooted down. Use a sharp knife to cut through the runner about 5cm (2 inch) from the tip, thus releasing the rooted plantlet. Plant it in a 8cm (3 inch) pot of the preferred potting mixture for adult plants and treat it in the same way as a mature specimen.

Nephrolepis exaltata will shed fronds if potting mixture dry out, at which point all fronds may be cut back to about 5cm (2 inch) to regenerate.

Pythium or Phytophthora: Symptoms include stunting, wilting, and graying or yellowing of the foliage. More likely to occur in cool, dark weather and cool, wet media.
Treatment: Fungicides remain an important method to control losses due to Phytophthora and Pythium spp.

Rhizoctonia: Aerial blight that occurs mostly in the summer. Symptoms include brown irregular lesions commonly in the crown of the plant.
Treatment: Apply adequate fungicides. Be certain the Nephrolepis spp. to be treated is listed on the fungicide label.

Oval or round brown spots indicate fern scale.
Treatment: It the attack is mild remove the insects with a cotton swab dipped in diluted methylated spirits. Combat major attacks with a suitable insecticide. Care should be taken as some of these insecticides are not suitable for ferns.

Grey, pale or crumpled fronds indicate an attack of red spider mites.
Treatment: Submerge the whole plant in a bath of trepid water for 10 minutes. Drain well, keep evenly moist and mist to keep humidity high. Place the plant in good light. Mites are only comfortable in hot dry surroundings, so will perish if these conditions do not exist.

Small white insects on fronds occur if the plant is host to mealy bugs.
Treatment: Mild attacks can be dealt with using   cotton tipped swabs dipped in diluted methylated spirits. Combat severe attacks with careful use of a suitable insecticide. Follow the label instruction for use.

Lifespan: Give to Nephrolepis exaltata good light and adequate humidity and it will grow for many years.

Availability: Nephrolepis exaltata are available all year from garden centres and nurseries.  Buy fresh green looking plants of a reasonable size.

Note: Nephrolepis exaltata is classified as an invasive alien plant in South Africa. In some provinces it must, by law, be eradicated. In others, a permit is required to import, possess, grow, breed, move, sell, buy or accept one as a gift.

Recommended varieties: Nephrolepis exaltata cv. Bostoniensis has gracefully arching  wavy or curly fronds. It is one of the oldest and probably the most popular variety.

Uses and Display: A mature Nephrolepis exaltata, with its cascading mass of fronds will look impressive in any settings. Stand it on a medium height cane table to create a nostalgic hint of the Victorian era when ferns were more popular than today. Also Nephrolepis exaltata are ideal plants for hanging baskets. But remember that hanging baskets tend to dry quickly, so check the potting mixture to not dry out. Many prefer to keep the ferns in bathrooms, but only do this is the light is bright.
Small plants will fit onto windowsills but larger ones will need more space and should be place a little further into room.
It is used as a specimen or accent plant in large containers. Hanging baskets are often filled with this fern.

Nephrolepis exaltata is a perennial hardy plant used in warm climate zones as erosion control plant, ground cover, massing or woodland garden. It is used in landscape along walks, in front of taller growing shrubs and as a ground cover under trees.

Nephrolepis exaltata is acting as a natural air humidifier, removes formaldahyde and is a general air purifier. It said to be among the best in air purifying houseplants.
On the other hand, these ferns are known to be non-toxic, so it is safe to grow them around kids and pets.


Foliage – green
Shape – upright
Height: 60-90cm (24-36 inch)

Watering in rest period – moderately
Watering in active growth period – plentifully
Light – bright filtered
Temperature in rest period – min 10°C max 13°C (50-55°F)
Temperature in active growth period – min 13°C max 24°C (55-75°F)
Humidity – high

Hardiness zones: 9-11

Nephrolepis exaltata Nephrolepis exaltata Nephrolepis exaltata varieties

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