Niʻaniʻau looks very nice and does well in the landscape under large shrubs or trees. Kidney-shaped sori, on the underside of a frond, are characteristic of this fern family.

Niʻaniʻau can be planted as a groundcover or used in a large hanging basket or in large containers such as an old concrete sink.

Growth Requirements

General

    The beautiful niʻaniʻau or ʻōkupukupu fronds can reach over four feet in length and sweep down the sides of the container it is grown in. This fern is perfect for deep pots, old concrete sinks, toilet tanks, or hanging baskets in areas that receive partial shade to near full shade. Once these ferns are established, it will begin to send out rhizomes and produce new plants with its own set of fronds. These can easily be separated from the mother (main) fern to create new plants without disturbing the entire pot. However, it is recommended to repot these ferns every one to two years to prevent them from becoming root-bound and from plantlets emerging from the drainage holes.

    For dense groundcover, space the niʻaniʻau 1-1.2 m (3-4 ft) apart. If you wish to showcase their sweeping fronds, space them further apart at 1.5-2 m (5-6 ft.) These ferns thrive in a rich organic soil mix in moist but do not appreciate waterlogged soil. Providing some sun protection, such as planting them under tall shrubs or trees, will help the ferns maintain their vibrant dark green color. Sometimes niʻaniʻau will even climb trees or hapuʻu, especially if leaf litter or debris has been collected in tree crotches.

    Niʻaniʻau prefers north and east-facing locations, but can also be planted on the west and south sides with proper protection from intense sunlight, especially during the summer months. Similar to the Boston fern, niʻaniʻau make excellent indoor plants and are safe for children, cats, and dogs [Verdant Dwellings].

    To ensure optimal growth and health of your plants, it is recommended to use a 13-13-13 slow-release fertilizer every six months for plants in pots or planted in the ground. For larger potted ferns that are displaying poor color or not producing crosiers (fiddleheads or emerging fronds), it is advised to use a complete fertilizer at half the recommended strength. Kay Lynch (Lāʻau Hawaiʻi/Hawaiʻi Fern Project), suggests avoiding tilling solid fertilizers into the soil, as palapalai has a shallow root system and can damage roots.

    Niʻaniʻau thrives on foliar feeding with fish or kelp emulsion and can benefit from occasional feedings with Miracle-Gro® fertilizer for acid-loving plants at half the recommended strength. The Boston fern (Nephrolepis exaltata) is known to be somewhat drought-tolerant, but our native plants typically perform best with a reliable source of moisture.

To maintain a tidy appearance, dead fronds should be pruned off regularly, especially if the ferns are being used as indoor plants, as the dead pinnae can create a mess as they drop to the ground. By following these guidelines, you can ensure that your ferns remain healthy and vibrant.

Pests and Diseases

    Mealybugs can be a nuisance and should be treated right away. Scale can infest the stip (midrib). Occasionally, caterpillars can damage the fronds. Look for curled fronds with webbing for the pest.

    Refer to the Pests & Diseases page for treatments.  

Special Features and Information

General

    Nephrolepis exaltata formerly belonged to Lomariopsidaceae. However, it has now been placed in its own family Nephrolepidaceae or the Sword Fern family, with about 30 species. Several common naturalized sword ferns have hybridized with the native species [Palmer 2003]. The only other native Nephrolepis species in the Hawaiian Islands is niʻaniʻau and kupukupu (Nephrolepis cordifolia), a very close relative of N. exaltata [Nephrolepidaceae]. Over the years, there has been a seemingly back and forth taxonomic challenge as to the botanical name of this species as to whether is Nephrolepis exaltata or Nephrolepis exaltata subsp. hawaiiensis, an endemic subspecies. As of 2025, this species is recognized as Nephrolepis exaltata, an indigenous fern [Imada et al. 2025]. 

    The name True ʻŌkupkupu is used to distinguish niʻaniʻau from the False ʻŌkupkupu (Nephrolepis multiflora) [Smathers et al. 2007].

Hawaiian Name

    Kupukupu is a term used to refer to ferns that grow on a single stem, with "kupu" meaning to sprout [Hawaiian Dictionaries]. In ancient Hawaiian culture, kupukupu was often placed on hula altars to symbolize the sprouting of knowledge. For this website, we have chosen to use niʻaniʻau to specifically distinguish it from Nephrolepis cordifolia since they both share the same Hawaiian names of kupukupu and ʻōkupukupu.

    Alternate names, rarely used, for the featured species are Palapalai, a specific type of fern found on Niʻihau, and Pāmoho, another Hawaiian name for the indigenous spleenwort fern, Asplenium unilaterale.

Etymology

    The generic name Nephrolepis is derived from the Greek nephros, kidney, and lepis, scale, in reference to the kidney-shaped indusia (sori covering) [Palmer 2003]. The Latin specific epithet exaltata, raised, high, lofty, alludes to the upright fronds of this fern [Palmer 2003]. The former subspecific epithet hawaiiensis is from Hawaiʻi, + -ensis, the place of origin [Palmer 2003].