Iliau (Wilkesia gymnoxiphium)

Photo: KarlMCC BY-SA 3.0via Wikimedia Commonsresized / cropped

Iliau Plant Care

Wilkesia gymnoxiphium A.Gray

Updated · Sources · How we source care data

Wilkesia gymnoxiphium (Hawaiian iliau), is a species of flowering plant in the family Asteraceae that is endemic to the island of Kauaʻi in Hawaiʻi. It is classified as endangered on the IUCN Red List. Wilkesia is one of three genera, with Argyroxiphium (silverswords and greenswords) and Dubautia (a larger group with many varied species) that are believed to be descendant from a single species related to the North American tarweed. The members of these three genera constitute what is called the silversword alliance, a group whose exceedingly close genetic heritage is not reflected in their exceptionally diverse morphologies.

🌱Herbs🌼Perennials🌻Annuals
Water

Every 7–10 days

Light

Full sun to partial shade

Temp

60–80°F

Humidity

40–60%

At a glance

How do you care for Iliau?

Plant Iliau in full sun to partial shade (USDA zones 13a) and water a young shrub every 7–10 days until it is established. It tolerates temperatures of 60–80°F (16–27°C). Fertilize it every 6 months during the growing season.

What Is the Iliau?

Iliau (Wilkesia gymnoxiphium) belongs to the Asteraceae family within the Wilkesia genus. Iliau is native to the island of Kauaʻi in Hawaiʻi. Iliau is also known as Argyroxiphium gymnoxiphium.

Iliau displays a low rosette, clumping growth habit, reaching up to 0.5 ft tall with a spread of approximately 1 ft. Iliau produces small daisy-like flowers in shades of yellow or orange.

Leaf size: approximately 4 inches.

How Often Should You Water a Iliau?

Water a young or newly planted Iliau every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Watering Frequency

Every 7–10 days

Until established; then in dry spells

What Light Does the Iliau Need?

Iliau thrives in full sun to partial shade.

Light Requirement

Full sun to partial shade

What Temperature and Humidity Does the Iliau Prefer?

Wilkesia gymnoxiphium tolerates temperatures of 60–80°F. Iliau prefers humidity levels of 40–60%.

Temperature

60–80°F

Humidity

40–60%

What Soil Mix Works Best for a Iliau?

Well-draining sandy soil with added organic matter for moisture retention. Good drainage is essential for Iliau to prevent waterlogging, which leads to root rot and fungal issues.

How Often Should You Fertilize a Iliau?

Feed Iliau every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

Fertilizing

Every 6 months

During the growing season

The PlantoScan app can remind you when to water and when to fertilize each plant.

Where Should You Plant a Iliau?

Choose a spot with full sun to partial shade and well-draining sandy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

Iliau is suited to USDA Zone 13a.

Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.

How Far Apart Should You Plant a Iliau?

Iliau can spread to about 1 ft (0.3 m) and reach about 1 ft (0 m) tall. Space plants about 1 ft (0.3 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the plant spacing calculator.

How Do You Prune a Iliau?

Prune Iliau while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the shrub in one year.

How Do You Care for a Iliau in Winter?

Iliau is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

How Do You Propagate a Iliau?

Iliau can be propagated through seeds, division of offsets. Similar propagation techniques also apply to ili'au plant care, which shares the same genus.

Is the Iliau Toxic to Pets and Children?

Pet safety not verified

The ASPCA does not list Iliau, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.

This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.

See all plants toxic to cats and plants toxic to dogs.

What Pests and Diseases Affect the Iliau?

Iliau is susceptible to aphids, spider mites, mealybugs. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

What USDA Hardiness Zone Does the Iliau Need?

Iliau grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Iliau is native to the island of Kauaʻi in Hawaiʻi. In cooler regions, grow Iliau as a houseplant or bring it indoors before the first frost.

Hardiness Zone

Zone 13a

Keep exploring plants

Iliau is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.

It belongs to the Wilkesia genus — compare its care with other Wilkesia species on PlantoScan.

Wilkesia is part of the Asteraceae plant family — browse all Asteraceae genera and species.

Iliau thrives in bright light and direct sun — see other bright-light plants.

Related Plant Care Guides

Closely related plants with similar care requirements:

Sources

  • Scientific name & taxonomy: Wilkesia gymnoxiphium A.Gray, family Asteraceae (first published in Proc. Amer. Acad. Arts ii. (1852) 160) — World Flora Online record, IPNI name record.
  • Pet toxicity: Pet safety not verified: the ASPCA does not list Iliau, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
  • Photo: KarlM, CC BY-SA 3.0, Wikimedia Commons — original.
  • Hardiness zone: USDA Zone 13a, calculated from the plant's minimum temperature.
  • Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.

Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.

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