The Crown Flower Plant (Calotropis gigantea), also known as Giant Milkweed or Gigantic Swallowwort, is a striking tropical shrub known for its unique, long-lasting blossoms. It typically grows up to 15 feet tall in its native environment. The flowers are the most distinctive feature, presenting in waxy clusters of white or pale lavender, with five pointed petals surrounding a small, central crown-like structure. Its large, oval leaves are a light grey-green color, often featuring a white, wooly coating when young. Culturally, the flowers hold significance in various tropical regions, including being favored in Hawaii for stringing into leis.
Environmental Needs for Establishment
The Crown Flower Plant is a sun-loving species that requires full sun exposure, needing at least six hours of direct sunlight daily to thrive. Insufficient light will cause the plant to become leggy and can significantly reduce flower production.
The Crown Flower is highly adaptable but performs best in well-draining soil that prevents water from accumulating around the roots. A sandy or loamy soil composition is ideal, though the plant can tolerate poor, nutrient-deficient soils. Waterlogging is detrimental to this species.
The plant prefers a slightly acidic to slightly alkaline pH range (6.0 to 8.0). It thrives in warm conditions, preferring temperatures between 68 and 100 degrees Fahrenheit. It is hardy only in USDA zones 10 through 12, so gardeners in cooler climates should grow it in containers to move indoors and protect it from frost.
Ongoing Care and Feeding Schedule
Once established, the Crown Flower Plant exhibits strong drought tolerance. Watering should be done deeply but infrequently, allowing the top two to four inches of soil to dry out completely between applications. Overwatering is a common mistake and can quickly lead to root rot.
During the active growing season (spring and summer), the plant requires consistent moisture, but watering should be reduced significantly during cooler winter months when growth slows. For container-grown plants, check the soil weekly and apply water only if the soil is dry.
The Crown Flower is not a heavy feeder and generally requires minimal fertilization. If the soil is poor, a light application of a balanced, slow-release fertilizer can be applied at the start of the growing season in spring. Alternatively, a balanced liquid feed can be applied sparingly every four to six weeks during the spring and summer. Applying too much nitrogen-rich fertilizer can result in excessive foliage growth at the expense of flower production.
Pruning, Pests, and Safety Precautions
Pruning helps manage the plant’s size, encourages a bushier habit, and promotes new flowering wood. The most substantial pruning should be performed in early spring, before new growth begins, cutting back dead or weak stems to shape the shrub. A second, lighter pruning can be done in late summer to encourage a final flush of flowers, but avoid heavy trimming late in the season.
Throughout the growing season, consistent deadheading of spent blooms will encourage the plant to continue producing new flowers. Failure to prune can result in a sprawling, open plant with a tendency to accumulate dead wood. When pruning, make sure to use clean, sharp tools to ensure clean cuts and minimize stress on the plant.
The Crown Flower is generally resilient but can occasionally attract sap-sucking pests like aphids, mealybugs, and mites. At the first sign of an infestation, these pests can typically be managed using non-toxic methods such as insecticidal soap or neem oil.
The milky white sap, known as latex, is poisonous and contains compounds toxic to humans and pets if ingested. It is also a severe irritant to skin and can cause inflammation if it contacts the eyes. Always wear protective gloves and eye protection when pruning or handling any damaged part of the plant, and immediately wash any skin that contacts the sap.