The giant milkweed is a tropical relative of the common milkweed that grows into a large shrub or a small tree. It has large, attractively, sculpted flowers that are purple with a blue-tinted center. There is a white-flowered form that is often planted around temples in Asia. It is called the crown flower because the center of the flower resembles a crown. It is native to India, southern China, Malaysia and Indonesia, but has been extensively cultivated in tropical areas around the world. This milkweed family member typically grows to 8-15' tall. It is noted for its upright growth, milky sap, purple or white crown-like flowers, and white wooly shoots and leaves which mature to subglabrous. Flowers appear in clusters (umbellate cymes) throughout the year, but primarily in summer. Flowers (both white and purple) are commonly used in Hawaii for leis. Elliptic to oblong leaves (to 4-8" long) have cordate bases. Fruits infrequently form. This giant milkweed is an important larval plant for monarch butterflies. Where winter hardy, grow as a hedge or train as a small tree. Where not winter hardy, grow in containers which must be overwintered indoors. Thrives in medium moisture, well-drained soils in full sun. Established plants tolerate drought, but best growth and flower production occur in soils with consistent and even moisture. Zones 10-12.
- Put a mixture of potting soil and sand or perlite into a pot with drainage holes in the base. The soil should be moist and well-drained. Grows best in light, rich, evenly moist, well-drained soil in full sun. Tolerates some light shade. Tolerates some soil dryness.
- Sow the seeds on the soil.
- Cover the seeds with a thin layer of soil.
- Water the seeds. Keep the soil moist but not wet.
- When the plants are a few inches tall, they can be transplanted.