The flowers of lehua ʻāhihi differ a bit from those of some other Metrosideros, being less like a pompom and more like thinly-bristled paintbrushes (photograph courtesy of Gerry Carr CC BY-NC 4.0). These nearly ripe fruit capsules will soon turn black and woody, split open (via a cross-like opening), and release their numerous tiny seeds to the wind (photograph courtesy of Neal Kelso CC BY 4.0). Lehua ʻāhihi has shiny, hairless leaves with red petioles (leaf stems) and stems (photograph courtesy of J.B. Friday ©). Header photograph courtesy of Daniel Ward CC BY-NC 4.0).

Wild lehua ʻāhihi are often scraggly small trees growing on windswept ridges; note the other Metrosideros species growing nearby, visible on the top left and bottom of the photograph (photograph courtesy of Neal Kelso CC BY 4.0). However, in more sheltered locations, lehua ʻāhihi can become considerably larger and fuller (photograph courtesy of Hubert Szczygieł CC BY-NC 4.0). Two cultivated lehua ʻāhihi: one doing exceptionally well and another not so much (struggling plant photograph courtesy of Daderot Public domain).

Growth Requirements

General

    I (Koebele) am fairly certain no one reading this is going to like my advice, but here it is anyway. The best thing you can do with your lehua ʻāhihi is keep it in a pot. Growing any native Hawaiian Metrosideros (ʻōhiʻa) requires a considerable investment of time and care. It can take a year for a tiny ʻōhiʻa seed to sprout and grow into a seedling only six inches (15 cm) tall, a few years to have that seedling grow into a plant one would even consider putting in the ground, and several years before seeing a young ʻōhiʻa tree put out its first flowers. Of course, it’s possible to speed up this process a bit by growing ʻōhiʻa from cuttings. (However, growers have discovered that only some varieties or forms of ʻōhiʻa will root consistently and readily.) And, while this shortens the one-year seed-to-seedling stage and produces a plant that will begin flowering in just a year or so, it doesn’t eliminate the deadly microbial threats present, particularly in the soil (see Soils & Media; The difference between soil and media) that can kill an ʻōhiʻa rather quickly. There's a reason we don't see ʻōhiʻa trees lining the streets of Honolulu or Hilo.

    Fortunately, ʻōhiʻa do quite well in containers. I have seen stunning eight-foot-tall Metrosideros polymorpha (costing hundreds of dollars each) covered in flowers that were confined to a pot small enough that I was able to lift it by myself unassisted — of course, I was considerably younger when I did this! Additionally, keeping ʻōhiʻa permanently in a pot opens up opportunities for native Hawaiian plant lovers that don’t have yards or who live outside Hawai‘i. While I have only been growing ʻōhiʻa bonsai-style for a couple of years (see photographs below), others have been doing it successfully for decades [Pacific Bonsai Museum]. With the advent of cheap LED lamps, growing ʻōhiʻa indoors, either bonsai-style or by periodically transferring them to larger and larger containers, just got a lot easier. For the thousands of Hawaiians living outside Hawai‘i, wouldn’t you like a little piece of home — ʻōhiʻa is the most common and one of the most culturally significant native trees in Hawai‘i — growing in the corner of your living room or bedroom? Well, today, it’s really not that hard!

    If you do decide to keep your lehua ʻāhihi (or any native Hawaiian Metrosideros) in a container, here are some guidelines. 

    Growing native Hawaiian Metrosideros from seed can be fun and rewarding, but the details are beyond the scope of this website. If you are interested in trying, check out these two YouTube how-to videos by The HI Escapade:

• https://www.youtube.com./watch?v=pjB6Bp4adUA 

• https://www.youtube.com./watch?v=pbQe7ofVyBY. 

   Whether your lehua ʻāhihi (or other Metrosideros species) is grown from a seed or a cutting, I’ve found it’s best to wait until the plant is about six inches (15 cm) tall and actively growing before transferring it to a bonsai-style container. Metrosideros are prone to transplant shock. Therefore, be gentle and minimize any disturbance to the small plant’s root system. While all the native Metrosideros I’ve grown seem able to survive in a range of media mixes (provided the mix drains water easily), I’ve always been biased toward cinder-rich (75%-plus) mixes (with the balance being sphagnum peat moss) based on where I see so many wild Metrosideros growing. If you plan to let your lehua ʻāhihi grow large, you’ll need to carefully transfer it to larger and larger containers every couple of years. Keep your eye on the small drainage holes as well as the size of the plant to determine when it’s time for a transfer. Avoid premature transfers because the media-root mass can be difficult to transfer without some type of accident if the plant's roots don't extend and weave their way throughout the pot. Also, a small plant in a large pot means that much of the water absorbed by the media sits around and can become anoxic or promote the growth of unwanted algae, fungi, and bacteria. 

    Wild lehua ʻāhihi typically grow out in the open in cool, cloudy, and often rainy places. Try to mimic this temperature, light, and moisture environment for your cultivated lehua ʻāhihi. Indoors, this is easy using two or more full-spectrum LED lamps or panels. Outside, place your potted lehua ʻāhihi in a bright place shielded from the heat of the midday and afternoon sun (e.g., beneath an eave on the eastern side of your home). Keep your plant's container elevated to reduce the possibility of harmful microbes coming in from the ground. Always keep the media surrounding your lehua ʻāhihi roots moist but not waterlogged; a cinder-rich mix makes this task easier since it easily drains away excess water but also retains tiny water droplets in its many pores and crevices. If you are growing lehua ʻāhihi outside Hawai‘i, be mindful of the temperature, both day and night. This is a subtropical plant incapable of surviving below 50°F (10°C). So, don’t place your lehua ʻāhihi in that cold corner of your house or leave it outside; even summer nights might be too cold.

    Containerized lehua ʻāhihi require regular fertilization. While I prefer to use a low-dose fertilize-every-time-you-water fertilizer, I have also sometimes used granular controlled-release and foliar fertilizers and, therefore, don’t think the method of application is critical. Use either a balanced fertilizer or one low in nitrogen since you are trying to promote root growth and flower production, not excessive vegetative growth.

Three Metrosideros species doing just fine under full-spectrum LED lamps: a one-year-old M. tremuloides seedling, a two-year-old M. macrocarpus seedling, and a one-year-old M. polymorpha grown from a mature plant cutting. All are in 90%-plus black cinders in small bonsai-training pots. While these three plants are in my home on O‘ahu, please tell me why they couldn't be growing in someone else's home in Los Angeles, New York City, Paris, or Tokyo.

    For those readers who will only be satisfied with a lehua ʻāhihi in the ground, here are some guidelines from David (Eickhoff), who has had better success than me with this species in the ground.

    While lehua ʻāhihi may require a little more watering, it doesn't seem to be any more difficult to grow than Metrosideros macropus or M. polymorpha and can survive in lowland locations. Select a planting site with full or partial sunlight; mauka (easterly or northern) facing locations may be better than leeward (westerly or southern) facing locations. Consider using mulch to improve soil moisture retention in hot, open areas. 

    The planting site should have organic- or cinder-rich soil that easily drains water. Take extra care when planting your lehua ʻāhihi because they are sensitive to root disturbance. It's best to dig a planting hole about twice as large as the plant's root ball. Improve the drainage by placing black or red cinders at the bottom. When planting, never splay or in any way disturb the roots, but rather gently place the root ball in the hole as is. Be certain to plant your lehua ʻāhihi at the proper level, flush with or slightly above the surrounding soil; the new soil should never cover the area directly surrounding the trunk. A thorough watering, preferably topped off with a B-vitamin solution, will minimize any transplant shock and encourage new root growth. Water every one to two days until you see new growth, a sign of a successful planting. Then adjust the watering schedule to keep the soil moist.

    Lehua ʻāhihi benefits from regular applications of a balanced controlled-release fertilizer every six months. Foliar feeding in the early morning with a water-soluble fertilizer at ⅓ to ¼ the recommended strength every other month also seems to help. 

    Unsurprisingly, lehua ʻāhihi is highly wind tolerant. Because it tends to be shrubby, use this species as a flowering hedge or an accent in the landscape. If used as a hedge, avoid excessive pruning but instead take your time and prune over several weeks or months. When pruning, sterilize your hand-pruners with 70% or more isopropyl alcohol to prevent disease transmission. Lastly, David notes that, over many years, lehua ʻāhihi and Metrosideros polymorpha var. glaberrima are the only species of ʻōhiʻa that have sprouted and grown after broadcasting their seeds in his garden.

Pests and Diseases

    The most common pest for indoor lehua ʻāhihi is spider mites. Outside, be prepared for occasional infestations of scale insects and whiteflies or more lethal attacks by black twig borers. Caterpillars and Chinese rose beetles can also make your plant unsightly but are normally not lethal. Keep a watchful eye for Myrtle or ʻŌhiʻa Rust, a serious fungal disease that should be dealt with quickly. Refer to the Pests & Diseases page for more information and treatments for all the above-mentioned pests and diseases. Lastly, there is Rapid ʻŌhiʻa Death (ROD), an extremely deadly fungal disease. This disease is currently (2026) rare or absent from all the main Hawaiian Islands except for Hawai‘i Island, where it is a very serious threat to the native forests. While there are no reported cases of lehua ʻāhihi being infected by ROD, that situation could change. For the time being, if you are growing any native Hawaiian Metrosideros anywhere in Hawai‘i, keep yourself informed about this disease. Here are three ROD websites you can go to:

• CTAHR; ROD

• Hawaii Invasive Species Council

• ROD Strategic Response Plan

    While I (Koebele) have never seen the galls in the photograph below on cultivated lehua ʻāhihi, I have seen them on wild plants. They are caused by adult female psyllids (jumping plant lice) that lay eggs inside the leaves. When the eggs hatch, the nymphs feed on the leaf from inside and secrete substances that stimulate abnormal plant growth and form the galls. These attacks are not fatal, and if you see them on your lehua ʻāhihi, simply remove and dispose of the afflicted leaf (leaves) to break the psyllids' life cycle.

Special Features and Information

General

    Myrtaceae is a family of approximately 5,950 species within about 132 genera. The family is widely distributed in tropical and warm temperate regions of the world and is particularly diverse in Australia, Malesia, and the Neotropics. All species are woody, evergreen, and contain essential (volatile) oils, with many being trees. Historically, the family was divided into two groups: those with fleshy fruits and oppositely arranged leaves and those with dry dehiscent capsules with alternately or spirally arranged leaves. However, recent molecular studies have shown this division is artificial, and the family is actually polyphyletic [WikipediA;Myrtaceae].

    Both fleshy-fruited and dry-fruited Myrtaceae are present in Hawai‘i, primarily as introduced and naturalized species (over 50 species) but also with seven endemic and one indigenous species. Particularly common are tree species of the genus Eucalyptus, introduced and extensively planted in the early 1900s to recreate forest watersheds that were destroyed when feral cattle consumed much of Hawai‘i's native forests during the early and middle 1800s. Another notable introduced and naturalized Myrtaceae are the guavas, particularly strawberry guava (Psidium cattleyanum), which has proven to be extremely invasive in mesic areas, creating monocultures where there were once diverse native Hawaiian plant communities [Ziegler 2002].

    Native Hawaiian Metrosideros include the following: 

• Metrosideros macropus — small trees endemic to the Ko‘olau Mountain Range, O‘ahu.

• Metrosideros polymorpha — dwarf shrubs to very tall trees found on all the main Hawaiian Islands except Ni‘ihau and Kaho‘olawe. This is a very ecologically and morphologically diverse species, currently with eight formal varieties. It is also the most common native tree in Hawai‘i.

• Metrosideros rugosa — shrubs to small trees near or on the summit and windward cliffs of the Ko‘olau Mountain Range, O‘ahu.

• Metrosideros tremuloides — shrubs to small trees found in mesic to wet areas of the Ko‘olau and Wai‘anae Mountains, O‘ahu, particularly common on steep, windswept slopes.

• Metrosideros waialealae — shrubs and small trees most common on ridges on Kaua‘i, Moloka‘i, Lāna‘i, and Maui [Wagner et al. 1990].

    In addition to the five native Metrosideros, other native Hawaiian Myrtaceae include: the endemic and endangered nīoi (Eugenia koolauensis); an indigenous nīoi (Eugenia reinwardtiana); and the endemic ʻōhiʻa hā (Syzygium sandwicense) [Flora of the Hawaiian Islands].

Hawaiian Name

    In addition to being one of the names for Metrosideros tremuloides, ʻĀhihi can also mean "any plant with long runners or creepers, as cup of gold; any creeping vine," and is similar in meaning to the word hihi, which means "entangled" [Pukui & Elbert 1986].

    Wagner et al. [1990] and some other sources list ‘Āhihi kū ma kua as one of the Hawaiian names for Metrosideros tremuloides. While this name likely translates to "the ‘āhihi that stands on the ridgetop," — a very appropriate name — I (Koebele) was unable to find ‘Āhihi kū ma kua directly associated/defined in any of the Hawaiian dictionaries in Ulukau.

    Kūmakua is also the name of a strong wind [Pukui & Elbert 1986]. 

Etymology

    Metrosideros is derived from the Ancient Greek words, metro, meaning "mother-, centre-, heart-," and sidēros, meaning "iron," referring to the hard wood of these plants [etymonline; Gledhill 2008]. The species name, tremuloides, is from the Latin word, tremulus, meaning "trembling, shaking, quivering" [Gledhill 2008], combined with the suffix -oides, meaning "resembling" or "like" [Wiktionary], and refers to how the leaves of this species tremble in the wind.