Both the flowers and stem-tips (with their whorled leaves) of hinahina kū kahakai were and are popular in lei. Wild hinahina kū kahakai (like the one pictured here), because they usually receive very little water, often have their leaves more tightly spaced at their stem-tips compared to cultivated plants (Cultivated plant photograph courtesy of Greg Koob ©.). While this two-year-old hinahina kū kahakai is doing just fine under LED lamps, I'm still waiting for its first flowers. 

Growth Requirements

General

    Heliotropium anomalum makes a beautiful groundcover in xeric or coastal landscapes, particularly when planted in black cinder, which dramatically highlights its silvery foliage. Use a spacing of about two feet between plants for total ground cover and maximum weed suppression, or four or five feet apart to showcase each plant. Hinahina kū kahakai also does well as a container plant outside or indoors (under LEDs), provided the media mix drains well; fill the container with crushed coral, sand, or cinder. 

    Outside, hinahina kū kahakai needs at least six hours of full sun every day for optimal growth and health and does best in south- or west-facing sites. It is tolerant of extreme heat, drought, strong winds, salt spray, and even exposure to brackish water. It will grow in a variety of soils, including coralline, sand, lava/cinder, and even clay (provided there is good drainage).

    Heliotropium anomalum does not do well in constantly wet environments and will become less silvery, more leggy, and even die if given too much water. Allow the surface soil to dry between waterings, and then water only enough to keep the plant from wilting. In pots, provide the plant with regular but infrequent waterings; again, just enough to prevent wilting.

    While hinahina kū kahakai does best in coastal or low rainfall regions, it can also be grown in mauka (upland) and higher rainfall areas, provided it is planted in a site with maximum sunshine and excellent soil drainage. In areas of poor drainage, we recommend planting hinahina kū kahakai on a raised mound or ridge of cinder, crushed coral, or sand.

    Plants will benefit from foliar feeding with a water-soluble organic or inorganic fertilizer at ¼ -⅓ the recommended strength. However, too much fertilizer (no more than once a month) will result in a non-silvery gangly plant. An occasional soil drench or spraying of seawater also seems to benefit hinahina kū kahakai, perhaps due to a nutrient deficiency in synthetic fertilizers. However, seawater drenching/spraying is best reserved for potted hinahina kū kahakai or for planting areas dedicated to salt-tolerant plants, since once the salts are in the soil, it can be very difficult to leach them out.

    Hand-prune straggler branches to encourage new growth or maintain a desired shape. However, avoid excessive pruning because this can potentially kill the plant; prune no more than one-third of the stems at any one time, and then wait for new growth before pruning again.

Pests and Diseases

    Hinahina kū kahakai is occasionally attacked by aphids, mealybugs, scale insects, thrips, and nematodes, particularly when the plant is grown in a suboptimal environment (e.g., too much shade). Refer to the Pests & Diseases page for ways to deal with each of these pests and consider moving your plant to a better site. Infrequent sprayings of seawater also seem to deter some infestations. Fungal rot, resulting in dieback, can be a problem if the plant is overwatered. Avoid this by only watering when the surface soil is dry, and only planting in well-drained soil or in a container with a media mix that drains extremely well. 

Special Features and Information

General

    Heliotropiaceae is a family with approximately 450 species of small trees, lianas, shrubs, and herbs in three genera with a worldwide distribution; however, most species are found in the tropics and subtropics. Heliotropiaceae was considered a subfamily of Boraginaceae before 2016. [WikipediA;Heliotropiaceae]. 

    There are around 325 species of Heliotropium worldwide [WikipediA;Heliotropium], with two species native to the Hawaiian Islands, hinahina kū kahakai (H. anomalum) and kīpūkai (H. curassavicum), both coastal plants. Three non-native Heliotropiaceae are also found in Hawai‘i: the fourspike heliotrope (Euploca procumbens; syn. Heliotropium procumbens); the blue heliotrope (Heliotropium amplexicaule); and the tree heliotrope (Heliotropium arboreum; syn. Tournefortia arborea) [Flora of the Hawaiian Islands]. 

Hawaiian Name

    Hawaiians referred to several native plants covered with silvery hairs as hinahina, including the Hawaiian wormwood (Artemisia spp.), silversword (Argyroxiphium spp.), Hawaiian Geranium, and others. Hinahina kū kahakai is further identified as "the silvery plant that grows near the ocean" (kū kahakai) [Pukui & Elbert 1986]. Nohonohopuʻuone is the name for this plant on Niʻihau [Wagner et al. 1990].

Etymology

    Heliotropium is derived from the Greek words helios, for "sun," and trope, meaning "turning," in reference to the erroneous belief that Heliotropium flowers turn to face the sun [WikipediA;Heliotropium]. Leaves and flowers of other genera that turn toward the sun are referred to as heliotropic. The species name, anomalum, means "unlike its allies" or "out of the ordinary" [Gledhill 2008].