The large flowers are 4 to 6 inches in diameter. They are yellow, generally with a maroon center, and form singly or in small clusters at the ends of the branches. The staminal column is yellow. Garnett reports that the flowers open between 2 and 4 p.m. and close between 9 a.m. and 1 p.m.

Spring through early summer is the main blooming season with occasional flowers during the rest of the year. Garnett reports a flowering season of January through March for the subspecies found on O'ahu. (Bornhorst 1996; Criley 1998; Criley 1999; Garnett 1988; Koob 1999; Wagner 1990)

The best germination rate is obtained from fresh seed. Hibiscus hybridize easily and the seedlings may differ from the parent plant. To ensure that the seedlings are not hybrids, hand pollinate the flowers. Using a paint brush, transfer pollen to the stigma of the flower and then enclose the flower in a bag until the seed capsule ripens. Bornhorst (1991) recommends hand pollination in the early morning. The germination rate for Hibiscus brackenridgei seeds decreases significantly after one year. Soaking the seeds is not necessary, but it will speed up germination. Soaked seeds germinate in about one week.

Bornhorst (1996) states that Hibiscus brackenridgei can be grown from seed, but cuttings are faster. Garnett, on the other hand, feels that seed propagated plants are more vigorous. Woolliams reports that Hibiscus brackenridgei subsp. mokuleianus becomes an 18 foot tall tree when grown from seed, but is a 6 to 8 foot tall shrub when grown from cuttings. (Bornhorst 1990; Bornhorst 1991; Bornhorst 1996; Garnett 1988; Koob 1999; Wagner 1990; Woolliams 1980)

Bornhorst recommends cuttings 4 to 6 inches long and less than 1/2 inch in diameter should be made from healthy branches without flower buds. Garnett recommends that cuttings should be at least 1/4 inch in diameter.

A loose, well-drained medium should be used such as either 1 part coarse perlite to 1 part vermiculite or 100% vermiculite. The rooting medium should be kept moist. Bornhorst (1991) reports the successful use of a mist system which was one for 24 seconds every 3 minutes. Criley's work was done using an intermittent mist system which was on for 6 to 8 seconds every 5 or 6 minutes; cuttings were rooted under 30% shade.

At Waimea Arboretum, cuttings treated with rooting hormone and rooted under intermittent mist were ready to be potted up in 8 weeks. (Bornhorst 1991; Criley 1998; Criley 1999; Garnett 1988; Woolliams 1980)

To start a plant by air layering, remove the bark and cambium from a 1 inch wide ring of bark. Apply a rooting hormone to the cut surface and cover this with a layer of damp sphagnum moss. Wrap the moss in plastic being sure to secure the ends where it wraps around the branch. (Bornhorst 1991)

Bornhorst, Heidi L. 1991. Propagating native hibiscus. Horticulture Digest (93):3-5.

Bornhorst, Heidi L. 1996. Growing native Hawaiian plants: a how-to guide for the gardener. Honolulu: The Bess Press. p. 46-47.

Criley, Richard A. 1998. Propagation of indigenous and endemic ornamental Hawaiian plants. Combined Proceedings of the International Plant Propagators' Society 48:669-674.

Criley, Richard A. 1999. Aloha Hawai'i. American Nurseryman 190 (3):50-61.

Garnett, William B. 1988. Plant Profile: Hibiscus brackenridgei A. Gray subsp. mokuleianus (M. Roe) D. Bates. Notes from Waimea Arboretum & Botanical Garden 15 (2):6-7.

Koob, Gregory A. 1999. Hawaii's State Flower: Ma'o Hau Hele. Hawai'i Horticulture 2 (10):5-7.

Wagner, Warren L., Darrel R. Herbst, and S. H. Sohmer. 1990. Manual of the flowering plants of Hawai'i. 2 vols., Bishop Museum Special Publication 83. Honolulu: University of Hawaii Press and Bishop Museum Press. p. 883-884.

Woolliams, Keith. 1980. Oahu yellow hibiscus found. Notes from Waimea Arboretum & Botanical Garden 7 (1):9, 12-13.