Calotropis gigantea aka Crown Flower

Calotropis gigantea is remarkably adaptable to different soil types, thriving in light sandy, medium loamy, and even heavy clay soils. It prefers well-drained, littoral (coastal) sandy soils but succeeds in nutritionally poor and even saline conditions. The pH can range from mildly acidic to mildly alkaline. Good drainage is essential as the plant is susceptible to root rot in waterlogged conditions.

Calotropis gigantea is a fast-growing evergreen shrub that typically reaches 4-5 meters (13-16 feet) in height with a spread of up to 6 meters (19 feet). In optimal tropical conditions, exceptional specimens can grow to 10 meters. The plant develops a much-branched habit from the base with stems up to 20cm in diameter. Growth is rapid in warm climates with full sun.

Calotropis gigantea is a tropical plant that thrives in warm temperatures and cannot tolerate frost. It grows best in USDA zones 10-12 where temperatures remain above freezing. The plant is damaged by temperatures below 0°C (32°F) and should be protected or brought indoors in cooler climates. In its native range, it thrives in hot conditions up to 1,400 meters elevation.

Calotropis gigantea actually prefers lower humidity and thrives in drier tropical climates with distinct dry seasons. Unlike many tropical plants, it does not require high humidity and performs well in arid conditions.

Calotropis gigantea requires minimal fertilization as it naturally thrives in poor, nutrient-depleted soils. The plant can grow successfully in waste land unsuitable for other crops. If desired, a light application of balanced fertilizer during the growing season can promote flowering, but over-fertilization is unnecessary and may actually reduce the plant's hardiness.

Calotropis gigantea produces stunning waxy flowers year-round in tropical climates, with peak flowering during summer and the hot season. The flowers appear in dense clusters (umbellate cymes) and feature five pointed petals that curve backward, with colors ranging from white to pale purple or lavender. Each flower has a distinctive five-pointed crown rising from the center, giving the plant its common name 'Crown Flower.'

Calotropis gigantea uses a specialized 'translator mechanism' for insect pollination. Pollen grains form coherent masses called pollinia that attach to visiting insects via sticky translator arms. Carpenter bees (Xylocopa species) are the primary pollinators, though wasps, honeybees, and butterflies also visit. The plant has co-evolved with carpenter bees, and the relationship between flower nectar production and bee water requirements is finely balanced.

Calotropis gigantea can be propagated by seeds, stem cuttings, or layering. For seeds, allow pods to dry on the plant and split open naturally before collecting. Sow in well-draining soil and keep warm and moist until germination. Stem cuttings should be taken from mature plants and rooted in sandy soil. Wear gloves when handling seeds and cuttings as the latex can cause skin irritation.

Calotropis gigantea tolerates pruning well and can be shaped as a hedge or maintained as a smaller specimen. Prune in late winter or early spring before the main growth flush. The plant responds well to hard pruning and will resprout vigorously. Always wear protective gloves and eye protection when pruning as the milky latex that exudes from cuts can cause skin irritation and serious eye injuries.

Calotropis gigantea grows best outdoors in USDA zones 10-12 where it can reach its full potential as a large shrub. It's excellent for seaside gardens due to salt tolerance and thrives in hot, dry conditions. In cooler zones (9 and below), grow in containers that can be moved indoors during winter. The plant needs full sun and cannot tolerate frost or freezing temperatures.

Calotropis gigantea is primarily available in two flower color forms: the common purple/lavender variety and the white-flowered form. Named cultivars include 'Alba' (white flowers) and 'Andromeda' (a rare white variety sometimes called White Madar or Albino Crown Flower). The purple form may be sold as 'Purpurea.' Both colors are popular for Hawaiian leis and traditional floral arrangements.

Calotropis gigantea is remarkably pest and disease resistant. Missouri Botanical Garden notes 'no serious insect or disease problems.' The milky latex contains toxic compounds that deter most herbivores and insects. The main concerns are root rot in waterlogged soils and potential damage from extreme cold. Monarch butterfly caterpillars feed on the foliage but rarely cause significant damage.

Calotropis gigantea has extensive traditional medicinal uses in Ayurveda, Siddha, and Unani medicine systems. The latex is used externally for wounds, boils, burns, sprains, and skin conditions. Internally (with extreme caution), preparations have been used for fever, coughs, asthma, dysentery, and rheumatism. The plant contains cardiac glycosides with digitalis-like effects. Always consult healthcare professionals before any medicinal use as all parts are toxic.

Calotropis gigantea has numerous practical applications. The stem bark yields strong fiber (called 'Bowstring of India') for textiles, ropes, and fishing nets. Seed floss serves as kapok substitute for stuffing and has water-repellent properties useful for life jackets and oil spill cleanup. The wood makes quality charcoal historically used in gunpowder. The plant is also used for soil stabilization, hedging, and reclaiming waste land.

Crown Flower requires a bit more attention and knowledge to thrive, making it a suitable plant for those with some gardening experience.

Crown Flower’s native range is E. Asia - southern China, Indian subcontinent, Myanmar, Thailand, Laos, Vietnam, Malaysia, Indonesia.

Crown Flower should be watered regularly, allowing the soil to dry out between waterings.

Crown Flower requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Crown Flower will be sure to bring you many years of beauty and enjoyment.

Ploi does not possess verified information regarding the toxicity of this particular plant. In the event that you, a member of your family, or a pet ingests plant material with an unclear toxicity level, it is highly recommended to seek the advice of a medical professional.