# Swamp Milkweed (Asclepias incarnata)

> The best-behaved milkweed there is: a tidy, clump-forming, non-running perennial with narrow willow-like leaves and domed clusters of vivid rose-pink flowers that smell faintly of cinnamon. It grows in wet ground in the wild but is perfectly happy in ordinary garden soil, which makes it the safest choice for a border.

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

## Summary

The best-behaved milkweed there is: a tidy, clump-forming, non-running perennial with narrow willow-like leaves and domed clusters of vivid rose-pink flowers that smell faintly of cinnamon. It grows in wet ground in the wild but is perfectly happy in ordinary garden soil, which makes it the safest choice for a border.

## Key facts

| Field | Value |
| --- | --- |
| Scientific name | Asclepias incarnata L. |
| Genus | Asclepias |
| Family | Apocynaceae |
| Common names | Swamp Milkweed, Rose Milkweed, Marsh Milkweed, Pink Milkweed |
| Status | Native |
| Height | 3 ft–5 ft |
| Spread | 2 ft–3 ft |
| Flower color | pink, rose, white |
| Bloom period | June to September |
| Light | Full sun, Part shade |
| Soil moisture | Wet, Average |
| USDA zones | 3-9 |
| Leaf arrangement | opposite |
| Leaf shape | lanceolate |
| Sap | Milky latex |
| Root system | Fibrous, clump-forming and easy to move |
| Seed stratification | 30 days cold-moist |
| Monarch value (0-5) | 5 |
| Garden value (0-5) | 5 |
| Nectar value (0-5) | 5 |
| US states recorded | Alabama, Arkansas, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Wisconsin, West Virginia, Wyoming |

## Identification

- Narrow, smooth, willow-like leaves on a slender stem that branches near the top.
- Flowers are a much brighter, cleaner pink than common milkweed, in neat rounded clusters held upright.
- Pods are slim, smooth and spindle-shaped, never warty.
- Forms a discrete crown; it does not send up shoots away from the plant.

## Ecology

Excellent monarch host and outstanding late-season nectar plant, blooming when common milkweed has finished. Great spangled fritillaries, tiger swallowtails and long-tongued bees dominate the flowers. Because it holds foliage late and stays soft, it often carries the last monarch generation of the year in the Midwest and Northeast.

## Growing

The one to plant if you only plant one. It stays where you put it, tolerates clay, standing water and rain gardens, and takes ordinary garden watering without complaint. Slow to emerge in spring. Cut back in late winter. Divides easily, unlike its taprooted relatives. The white form ‘Ice Ballet’ and compact ‘Cinderella’ are widely sold.

## Cautions

Low toxicity risk in gardens. Aphid magnet. Expect orange oleander aphids, and leave them for the ladybirds rather than spraying, which kills monarch eggs.

## Questions

**Does swamp milkweed need a swamp?**

No. It is adapted to wet ground but grows well in average garden soil with normal watering. It simply will not tolerate prolonged drought the way butterfly weed does.

**Is swamp milkweed aggressive?**

No. It is fibrous-rooted and clump-forming, the least aggressive of the widely grown milkweeds and the right choice for a mixed perennial border.

**When does swamp milkweed bloom?**

Mid to late summer, typically July into September, later than common and showy milkweed. That makes it valuable for the final monarch generation of the season.

## References

- Plants of the World Online: https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:94351-1
- GBIF: https://www.gbif.org/species/3170266
- iNaturalist: https://www.inaturalist.org/taxa/125381
- Wikipedia: https://en.wikipedia.org/wiki/Asclepias_incarnata
- BONAP county map: https://bonap.net/MapGallery/County/Asclepias%20incarnata.png
- NatureServe: https://explorer.natureserve.org/Search?searchTerm=Asclepias%20incarnata

## Photographs

- Asclepias incarnata 5-eheep (5097206759) (Superior National Forest, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_5-eheep_(5097206759).jpg
- Asclepias incarnata 4-eheep (5097804326) (Superior National Forest, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_4-eheep_(5097804326).jpg
- Asclepias incarnata 3-eheep (5097206621) (Superior National Forest, CC BY 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_3-eheep_(5097206621).jpg
- Asclepias incarnata - Swamp Milkweed (Fritzflohrreynolds, CC BY-SA 3.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_-_Swamp_Milkweed.jpg
- Asclepias incarnata (20617060945) (peganum from Small Dole, England, CC BY-SA 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_(20617060945).jpg
- Asclepias incarnata - Flickr - peganum (peganum from Small Dole, England, CC BY-SA 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_-_Flickr_-_peganum.jpg
- Asclepias incarnata - Flickr - peganum (1) (peganum from Small Dole, England, CC BY-SA 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_-_Flickr_-_peganum_(1).jpg
- Asclepias incarnata - Flickr - peganum (2) (peganum from Small Dole, England, CC BY-SA 2.0): https://commons.wikimedia.org/wiki/File:Asclepias_incarnata_-_Flickr_-_peganum_(2).jpg

## How to cite

Milkweed USA. (2026). Swamp Milkweed (Asclepias incarnata). https://milkweedusa.com/species/swamp-milkweed/