Cibotium glaucum is arguably the most common native tree fern seen in urban, suburban and country landscapes. It is easily distinguished from other hāpuʻu by its glaucous, or dull color, on the underside of the fronds. 

Growth Requirements

General

    Cibotium glaucum, commonly known as hāpuʻu, is the popular choice for landscaping in urban, suburban, and rural areas due to its availability and ability to thrive at lower near-sea level elevations, though it is not tolerant of salt. This tree fern can be used to add accents, provide partial screening, or be grown in containers. While it can handle full sun in a north-to-northeast direction at lower elevations, it thrives best in partial shade.

    Hāpuʻu is a slow-growing fern, adding only about an inch (2.5 cm) or so per year, making it beneficial to acquire larger trunks if possible. Cultivated hāpuʻu require regular watering, especially during hot months and when grown in containers, as they are not drought-tolerant. These ferns work well as understory plants, providing shade for more delicate foliage.

    To keep hāpuʻu healthy, occasional fertilization is recommended. Slow-release fertilizer should be applied every six months for container plants, while larger potted ferns showing signs of poor color or lack of crosiers should receive a complete fertilizer at half the recommended strength. Avoid tilling solid fertilizers into the soil, as ferns have shallow root systems that can be easily damaged.

    Hāpuʻu thrives in slightly acidic, well-drained soil with ample moisture. Brown and dried fronds can be trimmed for a neat appearance in landscaping, but avoid pruning emerging crosiers, as this can harm or kill the fern. It is advised to use hāpuʻu instead of the invasive Australian tree fern, Cyathea cooperi, which can escape gardens and compete with native plants. So, try to resist the urge to use non-native tree ferns so as to protect the local ecosystem.

Pests and Diseases

    For those living near forested areas, feral pigs are well known to eat hāpuʻu. Termites are a potential problem.

    Refer to the Pests & Diseases page for treatments. 

Special Features and Information

General

    Cibotium is in the family Cibotiaceae [Evenhuis 2011]. There are a total of 11 species of Cibotium worldwide, with four of them being endemic to the Hawaiian Islands. Unfortunately, feral pigs (puaʻa) have had a devastating impact on hāpuʻu populations in certain areas. These pigs consume the entire starchy inner core of the plants, leading to their destruction and creating breeding grounds for mosquitoes [Pratt 2005]. Overall, the presence of feral pigs poses a significant threat to the hāpuʻu fern populations, highlighting the delicate balance of ecosystems and the importance of conservation efforts.

    The pulu, or wool, found on these ferns is utilized by Hawaiian honeycreepers as nest lining [Pratt 2005].

Hawaiian Name

    The Hawaiian species are commonly referred to collectively as hāpuʻu, although the early Hawaiians gave specific names to each species. Cibotium glaucum is known as hāpuʻu pulu.

    To ensure proper pronunciation in modern times, hāpuʻu should be spelled with kahakō over the "a" (ā) [Hawaiian Dictionaries].

Etymology

    The generic name Cibotium is from the Greek kibotion, diminutive of kibotos, a box or casket, in reference to the indusium, a part of the fern blade that covers the sorus (spores) [Gledhill 2008]. The specific epithet is from the Latin glaucus, bluish green or gray, in reference to the color underneath the fronds [Gledhill 2008].