Giant milkweed (Calotropis gigantea)

Overview

The Giant milkweed, scientifically known as Calotropis gigantea, is a fast-growing, large shrub or small tree prized for its dramatic presence in warm climates. This tropical specimen offers year-round visual interest with its upright structure and unique, waxy, purplish or white crown-like flowers. It is a significant addition to tropical and subtropical landscapes where its texture and size can be fully appreciated.

As a member of the milkweed family, Calotropis gigantea provides crucial support for local ecosystems, notably serving as an important larval host plant for monarch butterflies. Although established plants tolerate dry conditions well, achieving the best flowering performance usually requires consistent, moderate moisture levels in full sun locations.

Gardeners value Giant milkweed for its low maintenance needs once established, making it an excellent choice for screening or creating bold architectural statements. Whether grown as a dense hedge or a trained accent tree, this robust plant brings an exotic flair to suitably warm environments.

Fast Facts

• Plant Family: Apocynaceae
• Plant Type: Broadleaf evergreen
• Native Range: Asia, tropical Africa
• Hardiness Zones: USDA Zones 11-12
• Size at Maturity:
  • Height: 8-15 ft
  • Spread: 8-15 ft
• Bloom Time: Seasonal bloomer
• Bloom Description: Pale purple or white
• Sun Exposure: Full sun
• Water Needs: Medium
• Maintenance Level: Low

How to Grow

Calotropis gigantea thrives when planted in well-drained soils that receive ample direct sunlight throughout the day. While it prefers consistent, medium moisture for optimal growth and heavy flowering, planting in the most protected, warmest sites in Zone 11 will ensure success. Avoid heavy, poorly draining sites where root health could suffer.

Water established plants moderately. While the Giant milkweed tolerates drought once mature, supplemental irrigation during long dry spells significantly boosts overall vigor and ensures better flower production. Fertilization is generally not required unless the soil is severely depleted.

Pruning is best reserved for shaping, especially if you intend to train the Calotropis gigantea into a small tree form rather than allowing it to develop as a multitrunked shrub. Propagate this species easily from stem cuttings taken from healthy wood.

Landscape Uses

The robust size and upright habit of Giant milkweed make it an outstanding choice for use as a specimen plant or for dense, fast-growing hedges where screening or wind reduction is desired. In its ideal climate (Zones 11-12), it can be shaped to serve as a small, informal specimen tree near patios or entryways.

Where winter protection is necessary, Calotropis gigantea performs beautifully as a container specimen. When overwintering indoors, ensure the large pot is placed in your sunniest location. Even when grown temporarily in containers, its striking foliage and dramatic blooms make it a worthy centerpiece.

Standout Features

Flower Qualities

• Showy

Noteworthy Characteristics

Calotropis gigantea, commonly called crown flower or giant milkweed, is a large shrub or small tree that 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 and is noted for its upright growth, milky sap, and crown-like flowers. This giant milkweed is an important larval plant for monarch butterflies.

Tolerances

• Drought

Potential Problems

Calotropis gigantea generally exhibits good resistance to common insect pests and diseases, contributing to its low maintenance status. However, gardeners must exercise extreme caution regarding its sap. The milky latex produced by the plant is highly irritating; avoid contact with eyes as it can cause severe inflammation, and be aware that it irritates mucus membranes. Handle pruning tasks with gloves and protective eyewear to minimize risk.

Frequently Asked Questions

What hardiness zones is Giant milkweed suitable for?

Calotropis gigantea is best suited for USDA Hardiness Zones 11 and 12, where it can survive year-round outdoors.

How large does Calotropis gigantea grow?

This species typically matures to a height and spread between 8 and 15 feet tall and wide, often taking on the form of a small tree or large shrub.

What sun exposure does Giant milkweed need?

This plant requires full sun exposure to maintain healthy growth and maximize its seasonal blooms.

When does Calotropis gigantea bloom?

It is a seasonal bloomer, typically producing clusters of pale purple or white, crown-like flowers throughout the year, with peak activity generally occurring in the summer months.

Conclusion

The Giant milkweed offers tropical drama, striking flowers, and vital support for butterfly populations, making Calotropis gigantea a rewarding choice for warm-climate gardening. Remember its toxicity warning concerning the sap when planning maintenance tasks. Ensure your location falls within USDA Zones 11 or 12 before planting this magnificent evergreen shrub outdoors.

Wildlife Benefits

Because Calotropis gigantea belongs to the milkweed family, it holds a special place in ecological gardening. It serves as a critical host plant for the larval stage (caterpillars) of monarch butterflies, allowing them to complete their lifecycle. Planting this species directly contributes to the conservation and proliferation of these iconic pollinators within your garden space.

Companion Planting

When placing Calotropis gigantea in a tropical or subtropical landscape, pair it with plants that share similar demands for full sun and medium moisture, especially when the milkweed is young or heavily irrigated. Good companions might include other heat-tolerant, large-leaved tropicals such as certain varieties of Hibiscus or Bougainvillea, which can handle similar soil profiles and sun intensity. This layering helps create a cohesive, lush look in the landscape bed.