Koki‘o ke‘oke‘o (Hibiscus arnottianus & H. waimeae) – is a shrub, right? 

    Like many malihini, the first time I saw a hibiscus was in 1982 when I came to O‘ahu to attend the University of Hawai‘i at Mānoa. And, like many visitors – and residents – for a long while, I assumed hibiscus were shrubs since that’s how they always appear along streets and surrounding houses or other buildings in Honolulu. Later, I discovered two facts: (1) nearly all the hibiscus in Honolulu are not Hawaiian at all but varieties or hybrids of the Chinese hibiscus (Hibiscus rosa-sinensis), (2) Hawai‘i does have native hibiscus species; two of these are referred to as koki‘o ke‘oke‘o because of their predominantly white flowers. Still, it wasn’t until I began hiking extensively (because of my growing interest in Hawai‘i’s native flora) that I learned a most unexpected fact: not all hibiscus are shrubs! In fact, koki‘o ke‘oke‘o (and some other native hibiscus) can grow into quite substantial trees 20-30 feet tall (see photograph). Of course, this leaves you, a native Hawaiian plant enthusiast, with a dilemma: “Should I let my koki‘o ke‘oke‘o grow naturally into a tree or prune it into a shrub?” For me, the answer is simple since I always prefer to see plants in their natural form. However, you may have a different preference. And, that’s okay because koki‘o ke‘oke‘o will thrive in your garden as either a tree or a pruned shrub. I’m just happy you’ve chosen a koki‘o ke‘oke‘o for your garden instead of yet another variety of Chinese hibiscus.

Habitat & Appearance: Hibiscus arnottianus is a shrub or tree (to 30 feet) that grows in dry to wet forests on O‘ahu and Moloka‘i. H. waimeae grows in mesic forests on Kaua‘i. Like most hibiscus, koki‘o ke‘oke‘o vary widely in leaf and flower morphology. This has led to the designation of unaccepted species names, as well as accepted variety names such as Kanani Kea and Shy Girl. Koki‘o ke‘oke‘o flowers are prized by plant-breeders because they are supposedly the only natural hibiscus species with a fragrance. H. waimeae is reported to be the most fragrant of the koki‘o ke‘oke‘o. The fragrant white flowers have led biologists to speculate that native moths may be (were) primary pollinators of koki‘o ke‘oke‘o. Koki‘o ke‘oke‘o flowers, with the exception of the subspecies immaculatus, bloom for two full days, in contrast to koki‘o ‘ula flowers which only last a day (Huppman 2013).

Koki‘o ke‘oke‘o in Hawaiian Culture: Hawaiians grew koki‘o ke‘oke‘o near their homes, using the flowers for medicine and the bark for cordage (Handy & Handy 1972, Bornhorst 2005). Many old songs and stories reference koki‘o ke‘oke‘o (Neal 1965).

Collecting Seeds: If you intend to grow koki‘o ke‘oke‘o from seed, you need to be concerned about seed purity. Koki‘o ke‘oke‘o easily and frequently cross-pollinate with other hibiscus near them, producing hybrid seeds. To be absolutely sure the seeds you are collecting are what you think they are, it’s safest to hand-pollinate bagged flowers. (Place a bag around the flower prior to its blooming. Open the bag and hand-pollinate with pollen from an identified source when the flower blooms. Re-close the bag around the flower, only removing it a week or so after it has bloomed.) Cultivated koki‘o ke‘oke‘o flower and fruit several times a year. Wait until the capsules are brown and dry before collecting them. Some capsules may split open and shed their seeds while others will not; seeds from either are equally viable. Check the often-fuzzy angular seeds for holes, and test their viability by dropping them into a dish of water. A few viable seeds may initially float. However, after a couple of hours, the viable seeds will have sunk to the bottom of the dish. Koki‘o ke‘oke‘o seeds are naturally exposed in the open capsule. Therefore, it’s best to sterilize all the seeds with bleach. Seeds remain viable for at least five years in the refrigerator.

Growing from Seed: Hot-water scarification, followed by either Method One or Method Two sowing, yields the greatest and most synchronous germination of koki‘o ke‘oke‘o seed. Most of the seeds will sprout in 2-3 weeks. Tiny seedlings are vulnerable to aphids, mealybugs, and mites with fatal results if not combated quickly (see Enemies in the Garden). Lightly fertilized, a seedling will grow quickly into a 6-10 inch tall plant within a few months; ready for planting into your garden. 

Growing from Cuttings: Use either Method One or Method Two to root koki‘o ke‘oke‘o cuttings. I normally see the first roots after 1-2 months. Wait at least another month for more root development before removing the plant from the container or mist chamber. Many hibiscus growers propagate several cuttings from a single branch with only one cutting being the stem-tip. This will work with koki‘o ke‘oke‘o, but, personally, I only propagate tip-cuttings because it results in an instantly more attractive plant. Other native plant propagators have grown koki‘o ke‘oke‘o using air-layers and even grafting. I’ve always been tempted to graft native Hawaiian hibiscus because, supposedly, it’s possible to create a single plant with separate branches from all the different native species or varieties. Can you imagine a hibiscus with red, orange, yellow, and white flowers! Or a koki‘o ke‘oke‘o composed of branches from the Kaua‘i, O‘ahu, and Moloka‘i species!  

Growth in the Garden: Your koki‘o ke‘oke‘o will grow best in a site receiving full sun to partial shade. There, the plant will grow rapidly, reaching three or more feet tall in a year. Most commercially available koki‘o ke‘oke‘o are propagated from cuttings, so, flowers often appear soon after planting even when the plant is very small. If you’ve grown your koki‘o ke‘oke‘o from seed, you’ll have to wait 2-3 years for the first flowers. How much you need to water a koki‘o ke‘oke‘o will depend upon the origin of your plant. Koki‘o ke‘oke‘o from Wai‘anae’s dry forests need watering only during drought periods, while plants from places like Mānoa in the Ko‘olau Mountains will require weekly watering. If you don’t know your plant’s origin, you’ll have to experiment and observe the plant until you discover its needs. Fortunately, nearly all koki‘o ke‘oke‘o possess some drought tolerance, permitting enough time for your koki‘o ke‘oke‘o to tell you, with wilted or yellowing leaves, that it needs more water.  

Diseases & Pests: Koki‘o ke‘oke‘o is occasionally attacked, usually at or near the stem-tips, by all the usual sucking insects: aphids, mealybugs, scale insects, and whiteflies. However, koki‘o ke‘oke‘o is a resilient plant, and attacks by these pests are almost never fatal. I normally wait for natural predators like ladybird beetles, lacewings, and mealybug destroyers to find and eliminate these pests. However, if the infestation doesn’t disappear on its own or you just don’t want to wait, several sprayings of horticultural oil mixed with a systemic insecticide will control these insects. Chinese rose beetles and grasshoppers sometimes get a taste for koki‘o ke‘oke‘o leaves. Refer to Enemies in the Garden if the damage becomes severe. The hibiscus erineum mite or hibiscus leaf-crumpling mite (Aceria hibisci) seems to prefer the Chinese hibiscus over native species (Thank goodness!). If you find this type of damage (i.e., leaves with pimples or other twisted distortions) on your koki‘o ke‘oke‘o, remove and discard the affected leaves or branches. If the problem persists, you can first try several sprayings of horticultural oil (about a week apart) before resorting to commercially available miticides. Miticides are tricky. Some are only available to licensed pest-exterminators. Check out your local garden shop, and ask them what’s available to you for combating the erineum mite. Be sure to read and follow the label directions since miticides are often only effective if the application protocol is followed exactly. 

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