| Light | Full sun |
|---|---|
| Water | Drought-tolerant once established; hates wet feet |
| Soil | Any well-draining soil, even poor and sandy |
| Size | 6–12 ft shrub; prune to keep at picking height |
| Flowers | Lavender or white crowns, year-round in Hawaii |
| Wildlife | The monarch butterfly host plant in Hawaii |
| Caution | Milky sap is toxic — wear gloves, keep from pets/kids |
| Best spot in Hawaii | Hot, dry, sunny — perfect for the leeward side |
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How do you care for a crown flower plant?
Crown flower is one of the easiest shrubs you can grow on O'ahu's dry side: give it full sun and well-draining soil, water regularly for its first few months while roots establish, then back off almost entirely. Mature plants shrug off drought, heat, wind, and poor soil — conditions that kill fussier plants are exactly what crown flower likes. The fastest way to kill one is kindness: rich soil, heavy watering, and soggy roots. Prune a few times a year to keep flowers within reach and the shrub full.
Why are caterpillars eating my crown flower?
Because that's the deal with this plant. Crown flower is a milkweed relative and the primary host plant for monarch butterflies (pulelehua) in Hawaii — female monarchs lay eggs on it, and the striped caterpillars eat the leaves, sometimes down to stems. A healthy crown flower regrows quickly, and most local growers plant it partly for the butterflies. Don't spray pesticides on a crown flower unless you're prepared to kill monarchs. If you want perfect leaves and lei flowers, grow two: one for you, one for the caterpillars.
What is the story behind the crown flower in Hawaii?
Crown flower — pua kalaunu — was famously the favorite flower of Queen Liliʻuokalani, Hawaiʻi's last reigning monarch. The small lavender or white blossoms look like tiny royal crowns, and strung into lei they were her signature. Lei pua kalaunu remain a beloved old-style lei today, fragrant of nectar and heavy with history. The plant itself came to Hawaiʻi from South and Southeast Asia and settled happily into island gardens, especially in hot, dry leeward neighborhoods like ours.
How do you propagate crown flower?
Crown flower grows readily from cuttings and from seed. For cuttings, take a pencil-to-finger-thick section of semi-hard stem about 8–12 inches long, let the milky sap drain and the cut end dry for a day or two, then stick it in barely moist, sandy mix in bright shade. It roots in a few weeks. Seeds from the fat pods germinate easily too — the silky floss carries them on the wind, which is why volunteers pop up around mature plants. Wear gloves whenever you cut: the white sap irritates skin and is dangerous to eyes.
What pests bother crown flower besides caterpillars?
The main freeloader is the oleander aphid — clusters of bright yellow-orange aphids on new growth and flower stalks. A hard blast of water knocks them off, and ladybugs usually keep them in check; avoid systemic insecticides, which poison monarch caterpillars feeding on the same plant. Spider mites can stipple leaves in dusty, dry spots (hose the foliage down occasionally), and mealybugs sometimes hide in leaf joints. Honestly, on a healthy plant in full sun, none of these do lasting harm.
Crown Flower FAQ
Is crown flower poisonous?
Yes — the milky sap contains cardiac glycosides and is toxic to people and pets if ingested, and seriously irritating to eyes and skin. Wear gloves when pruning and wash up after. This is also what makes monarch caterpillars that eat it distasteful to predators.
Does crown flower attract monarch butterflies?
Yes — it's the primary monarch host plant in Hawaii. Plant crown flower and monarchs will find it, lay eggs, and raise caterpillars on the leaves. Never spray it with pesticides if you want butterflies.
How big does a crown flower bush get?
Left alone, 10–12 feet or more. Most people prune it to 5–6 feet to keep flowers at picking height for lei making. It takes hard pruning well.
Can I grow crown flower in a pot?
Yes, in a large pot with sandy, fast-draining mix and full sun. It will stay smaller than an in-ground plant. Water deeply but infrequently.
🧰 Our favorite crown flower tools & supplies
What we actually reach for at the nursery:
- Sturdy garden gloves — non-negotiable — the sap is a genuine irritant
- Bypass loppers — for the woody stems when pruning to lei height
- Sandy planting mix or cinder — sharp drainage keeps roots happy
- Lei needle & string — 12-inch needles make quick work of pua kalaunu lei
- A second crown flower plant — one for lei, one for the monarchs 🦋
Heads up: some links on this page may become affiliate links, which means we may earn a small commission (at no extra cost to you) if you buy through them. We only recommend things we actually use in our own backyard.
Sources & further reading: University of Hawaiʻi CTAHR extension resources on crown flower and monarch butterflies in Hawaiʻi landscapes. Everything else comes from our own hands-on growing in Wai'anae, O'ahu.