Crown flower (giant milkweed, dok rak) Calotropis gigantea
Crown flower (giant milkweed, dok rak) (Calotropis gigantea) is an evergreen perennial shrub in the Apocynaceae family, native to Indian subcontinent to southern China and Malesia. It grows 1.5–4 m (4.9–13 ft) tall and 1.5–3 m (4.9–10 ft) wide, wants full sun and low water, and is hardy to about 2 °C (36 °F). Space plants about 1.5 m (4.9 ft) apart.
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Crown flower (giant milkweed, dok rak) at a glance
| Type | Perennial shrub, evergreen |
|---|---|
| Family | Apocynaceae |
| Mature height | 1.5–4 m (4.9–13 ft) |
| Mature spread | 1.5–3 m (4.9–10 ft) |
| Spacing | 1.5 m (4.9 ft) centre to centre |
| Sun | Full sun, at least 7 h of direct sun a day |
| Water | Low; drought tolerance high, waterlogging tolerance none |
| Soil pH | 5.5–8.5 |
| Cold hardiness | About 2 °C (36 °F) once established (roughly USDA zone 10) |
| Heat stress | Likely above about 46 °C (115 °F) |
| Flowering | about 34–52 weeks after planting, for 34–47 weeks |
| Wind tolerance | Moderate |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | Indian subcontinent to southern China and Malesia |
| Common in gardens of | 🇹🇭 Thailand, 🇮🇳 India, 🇮🇩 Indonesia, 🇲🇾 Malaysia, 🇺🇸 United States |
Is Crown flower (giant milkweed, dok rak) toxic?
- People: severely toxic
- Cats: severely toxic
- Dogs: severely toxic
- Parts: milky sap, leaves, all parts
All parts, especially the abundant milky latex, contain cardiac glycosides (calotropin): poisonous if eaten, and the sap can badly injure eyes. Wear gloves and glasses when pruning.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Crown flower (giant milkweed, dok rak)
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Questions about Crown flower (giant milkweed, dok rak)
- How far apart should I plant Crown flower (giant milkweed, dok rak)?
- About 1.5 m (4.9 ft) apart, centre to centre. A mature plant spreads 1.5–3 m (4.9–10 ft).
- Does Crown flower (giant milkweed, dok rak) need full sun?
- Full sun: at least 7 hours of direct sun a day.
- How much water does Crown flower (giant milkweed, dok rak) need?
- Low water. Drought tolerance is high and waterlogging tolerance none.
- How cold-hardy is Crown flower (giant milkweed, dok rak)?
- It tolerates about 2 °C (36 °F) once established, roughly USDA zone 10.
- When does Crown flower (giant milkweed, dok rak) flower?
- About 34–52 weeks after planting, for 34–47 weeks.
- Is Crown flower (giant milkweed, dok rak) poisonous to cats and dogs?
- For cats it is severely toxic; for dogs severely toxic; for people severely toxic. All parts, especially the abundant milky latex, contain cardiac glycosides (calotropin): poisonous if eaten, and the sap can badly injure eyes. Wear gloves and glasses when pruning.
- What grows well with Crown flower (giant milkweed, dok rak)?
- There is no well-documented companion pairing for Crown flower (giant milkweed, dok rak). Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- eFlora of India, eFlora of India / Botanical Survey of India contributors
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
Notes and assumptions
- Grey-green, waxy shrub of dry, poor ground. The waxy, crown-shaped lilac or white flowers are threaded into Thai wedding garlands (rak means "love") and Hawaiian lei; a food plant of monarch and plain tiger caterpillars.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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