Short inflorescence form closeup and cultivated plant. Long inflorescence form closeup (Photograph courtesy of J.K Obata via G.D. Carr ©) and cultivated plant (Note lower "immature" and upper "mature" leaf shapes.). The beginnings of a topiary (Photograph courtesy of Greg Koob ©). Header photograph courtesy of Greg Koob ©.

Growth Requirements

General

    Achyranthes humilis is an attractive easy-to-care-for shrub that should be more common in Hawai‘i landscapes. We suspect its endangered status, and thus its regulated commercial status, may be the reason for its rarity. Use kuluʻī as an accent plant, screen, or hedge. It can also be kept in a container.

    Kuluʻī does best in a site with full sunlight for all or most of the day, but is also tolerant of shade; shaded plants tend to be taller and more open-branched than full-sun plants. Once established, kuluʻī grows best with infrequent heavy waterings followed by long dry periods that permit the surface soil to dry out. It is tolerant of extreme heat and drought, and can grow in lava/cinder, clay, and organic-dominant soils, provided there is good drainage. We have not tried to grow kuluʻī in sand or coralline soil. Because kuluʻī are often propagated by cuttings, they lack a deep taproot, and can be toppled and uprooted by strong winds. Refer to Hibiscus arnottianus: Growth Requirements for how to prevent or deal with this potential problem.  

    Grounded Achyranthes humilis initially grow quite rapidly, and can be two or more feet tall in a year or less. They also begin flowering about this time. After this, growth typically slows down. While normally not necessary for in-the-ground plants, containerized kuluʻī benefit from biannual applications of a balanced (e.g.,13-13-13) controlled-released fertilizer or foliar feedings in the early morning (to avoid burning) with a water-soluble organic or inorganic fertilizer at ¼-⅓ the recommended strength every other month.

    Kuluʻī can withstand pruning provided it is done by hand. In fact, some native Hawaiian plant enthusiasts have even tried using kuluʻī as a topiary (see photograph above). If you do prune, be aware that kuluʻī cuttings are very easy to root — and, an easy way to give away this rare shrub to friends.

Pests and Diseases

    Kuluʻī is infrequently infested by sap-sucking insects like aphids, mealybugs, or scale insects. Look for infestations near the stem-tips and refer to the Pests & Diseases page for treatments. 

Special Features and Information

General

    Amaranthaceae is a large plant family with about 2,000 species within 165 genera with a global distribution; most species are herbs or shrubs, and many are known to cause pollen allergies [WikipediA;Amaranthaceae]. 

    In addition to Achyranthes humilis, other native Hawaiian plants in the Amaranth family (Amaranthaceae) include: five other endemic species of Achyranthes (one of which is extinct); five endemic species of pāpala (Charpentiera spp.); the endemic ʻāweoweo (Chenopodium oahuense); a possibly now extinct amaranth (Amaranthus brownii) endemic to Nīhoa; and an endangered amaranth (Amaranthus pakai) [Flora of the Hawaiian Islands].

Hawaiian Name

    It is worthy of note that while this species is often spelled with kahakō over the "i" as kuluʻī, Hawaiian Dictionaries traditionally spell kuluʻi, without kahakō over the "i" as kuluʻi.

Etymology

    Achyranthes comes from the Greek words, achyron, meaning "chaff," and anthos, meaning "flower," referring to the chaff-like parts of the flower [Wagner et al. 1990]. The former genus name, Nototrichium, comes from the Latin word, nota, meaning "remarkable," and the Greek word, tricho, meaning "hair," probably referring to the dense pubescence of these plants [Wagner et al. 1990]. However, Achyranthes humilis (syn: Nototrichium humile) does not have the characteristic dense silvery hairs on its leaves like its two sister species (A. divaricata, A. sandwicensis). 

    The species name, humilis, translates as "low-growing" or "close to the ground" [Gledhill 2008], which may be a reference to the decumbent growth behavior of some forms of this species.