# Tropical Milkweed (Asclepias curassavica)

> The scarlet-and-gold milkweed sold in nearly every garden center. It is not native to the United States, it flowers relentlessly, and in frost-free regions that is exactly the problem: it disrupts monarch migration and builds up parasite loads. Beautiful plant, genuinely bad ecological actor south of the frost line.

Source: https://milkweedusa.com/species/tropical-milkweed/  
Licence: CC BY 4.0 (Milkweed USA)

## Summary

The scarlet-and-gold milkweed sold in nearly every garden center. It is not native to the United States, it flowers relentlessly, and in frost-free regions that is exactly the problem: it disrupts monarch migration and builds up parasite loads. Beautiful plant, genuinely bad ecological actor south of the frost line.

## Key facts

| Field | Value |
| --- | --- |
| Scientific name | Asclepias curassavica L. |
| Genus | Asclepias |
| Family | Apocynaceae |
| Common names | Tropical Milkweed, Bloodflower, Mexican Butterfly Weed, Scarlet Milkweed |
| Status | Not native to the United States |
| Height | 2 ft–4 ft |
| Spread | 1.5 ft–2.5 ft |
| Flower color | red, orange, yellow |
| Bloom period | nearly year-round in frost-free areas |
| Light | Full sun, Part shade |
| Soil moisture | Average |
| USDA zones | 8-11 |
| Leaf arrangement | opposite |
| Leaf shape | lanceolate |
| Sap | Milky latex |
| Root system | Fibrous, clump-forming and easy to move |
| Seed stratification | None required |
| Monarch value (0-5) | 2 |
| Garden value (0-5) | 3 |
| Nectar value (0-5) | 4 |
| US states recorded | Alabama, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina, Texas |

## Identification

- Flowers are two-toned, a red or orange corolla with a bright yellow-orange crown, unlike any native species.
- Blooms continuously rather than in a defined season.
- Smooth, dark green lance-shaped leaves; slender upright stems; no basal woodiness in the first year.
- Pods are narrow, smooth and upright.

## Ecology

Monarchs will lay on it eagerly, but in the Gulf states, California and Florida it stays green all winter and encourages butterflies to break their migration and breed year-round. Those resident populations accumulate the protozoan parasite Ophryocystis elektroscirrha (OE), which shortens lifespans and deforms wings. Studies also show that cardenolide levels rise under heat, which may harm larvae.

## Growing

Grown as an annual north of zone 8 it is harmless and useful. It germinates without stratification, blooms in twelve weeks from seed and dies at the first frost. In zones 9 to 11, either cut it to the ground each October through February or, better, replace it with a native species.

## Cautions

Several US counties and native plant societies now discourage or restrict its sale. If you garden in Florida, the Gulf Coast, southern California, Arizona or Hawaii, please choose a native milkweed instead.

## Questions

**Is tropical milkweed bad for monarchs?**

In frost-free regions, yes. Because it does not die back it supports winter breeding, which raises OE parasite infection rates dramatically and can interrupt migration. In cold-winter regions where frost kills it each year, the evidence of harm is much weaker.

**Should I cut back my tropical milkweed?**

If you are in zone 9 or warmer, cut every plant to within six inches of the ground in October and keep it cut through February. That mimics the natural winter dieback and reduces parasite build-up.

**What should I plant instead of tropical milkweed?**

Match your region: swamp milkweed and butterfly weed almost anywhere, aquatic milkweed or pinewoods milkweed in Florida, zizotes and antelope horns in Texas, narrowleaf milkweed in California.

## References

- Plants of the World Online: https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:94213-1
- GBIF: https://www.gbif.org/species/3170241
- iNaturalist: https://www.inaturalist.org/taxa/75602
- Wikipedia: https://en.wikipedia.org/wiki/Asclepias_curassavica
- BONAP county map: https://bonap.net/MapGallery/County/Asclepias%20curassavica.png
- NatureServe: https://explorer.natureserve.org/Search?searchTerm=Asclepias%20curassavica

## Photographs

- Asclepias curassavica (bloodflower) 1 (26056089288) (James St. John, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(bloodflower)_1_(26056089288).jpg
- Asclepias curassavica (bloodflower) 2 (39030330915) (James St. John, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(bloodflower)_2_(39030330915).jpg
- Asclepias curassavica (BG Zurich)-01 (Guérin Nicolas (messages) 09:51, 25 September 2008 (UTC), CC BY-SA 3.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(BG_Zurich)-01.JPG
- Asclepias curassavica (BG Zurich)-02 (Guérin Nicolas (messages) 09:52, 25 September 2008 (UTC), CC BY-SA 3.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(BG_Zurich)-02.JPG
- Anartia amathea - Asclepias curassavica - Schmetterlinghaus Burggarten Wien 01 (Manfred Werner / Tsui, CC BY-SA 3.0): https://commons.wikimedia.org/wiki/File:Anartia_amathea_-_Asclepias_curassavica_-_Schmetterlinghaus_Burggarten_Wien_01.jpg
- Asclepias curassavica (5461131441) (carrotmadman6 from Mauritius, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(5461131441).jpg
- Asclepias curassavica (5461132859) (carrotmadman6 from Mauritius, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(5461132859).jpg
- Asclepias curassavica (15932169749) (John Tann from Sydney, Australia, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_curassavica_(15932169749).jpg

## How to cite

Milkweed USA. (2026). Tropical Milkweed (Asclepias curassavica). https://milkweedusa.com/species/tropical-milkweed/