Asclepias Incarnata

Swamp Milkweed for Monarch Butterflies
and Caterpillars

Asclepias incarnata: Swamp milkweed, Swamp silkweed, Rose milkweed, White Indian hemp

The BEST Native Milkweed for Butterfly Gardens? Swamp milkweed doesn't need to be grown in a swamp, but it does prefer moist soil. It doesn't spread through underground rhizomes so it won't take over your garden. It has a long summer bloom period that attracts many pollinators, and it receives many monarch eggs over the season. Asclepias incarnata is also a fantastic option for your container garden. More info and photos...
Swamp Beauty

Plant Specs:

Pros:

  • Takes over for fading common milkweed in summer
  • Popular nectar source for monarchs and other pollinators
  • Plays well with others, not an aggressive spreader
  • Easy to start from milkweed seeds
  • Sweet but subtle vanilla scent
  • Makes a great cut flower with its long lasting blooms
  • can use stem cuttings to raise monarch butterflies
Monarch Egg on Red Swamp Milkweed Buds
Swamp Egg

Cons:

  • Another milkweed species that aphids adore
  • Needs more moisture than other milkweed
  • Tiny pollinators buzzing around this can get annoying…however, this isn’t really a con since they’re pollinating your milkweed
  • Leaves are thin and dry out quickly when picked to feed monarch caterpillars

Plant Propagation:

  • Sow seeds directly in fall or spring
  • Start seeds indoors 2 months before final frost- cold stratification required
  • Winter sow for a natural cold stratification
  • Divide plants in late spring
Swamp milkweed works well as a container garden milkweed and attract butterflies with its pinkish, nectar-rich-blooms, while its leaves sustain monarch caterpillars. If you're in a dry region, potted swamp will probably perform much better than its garden grown siblings, but incarnata is really a great container idea for gardeners across North America.
Surprisingly Good in Containers

Swamp Growing Tips:

  • Slow release fertilizer is optional. Over-fertilization can inhibit flowering
  • Second year plants are a great option for growing in containers (not rhizomatous)
  • Cut off milkweed pods to prevent fall seeding
  • or bind them shut with twist ties or rubber bands if you want to collect asclepias incarnata seeds
A male monarch spends his golden years on swamp milkweed
Attract More Monarchs with Swamp Milkweed

Pollinator Plus:

Asclepias incarnata also attracts buckeyes, bumblebees, eastern tiger swallowtails, fritillaries, hairstreaks, honey bees, hummingbird moths, hummingbirds, skippers, spicebush swallowtails, and more… (If you know of others, please comment below.)

Resources:

1.

2.

3. Find Swamp Milkweed on Amazon

The links above also includes popular cultivars like ‘ice ballet’ (white), ‘Cinderella’, and ‘soul mate’. These have all been reported to attract monarchs too.

25+ Milkweed Plants Ideas for North American Butterfly Gardens

Please post below if you have any questions or comments about growing Swamp Milkweed in your butterfly garden:
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Comments

  1. Steff Mandarino says

    I live in the Atlanta area and planted asclepias incarnata in my garden about 5 years ago, right next to my asclepias tuberosa. The tuberosa blooms prolifically– the incarnata has never bloomed. Is it because the site is too dry?

    • says

      Incarnata typically blooms its second year. We grow ours in partial shade and this allows the soil to retain more moisture. If it’s planted in a dry area of your garden, I would try moving it…you’ve got nothing to lose if it hasn’t bloomed for 5 years. Good luck!

  2. Mary says

    I have a few plants of incarnata growing in partial shade and dry sandy soil on the New Jersey shore. It is doing very well, but the blooms do not last very long. We had monarch butterflies, eggs, and caterpillars this year. I just harvested twelve ounces of seeds from 6-8 plants. I also have many tuberosa plants nearby. The blooms last longer and it reblooms more readily when pinched back.

    • says

      Hi Mary, the short bloom period is likely the result of growing in dry, sandy soil. Swamp milkweed likes it wet. Congrats on all your eggs and caterpillars this season, and on your bountiful harvest!

  3. Mke Bryan says

    In Wisconsin we have a place called Prairie Nursery .I bought five plants last summer and planted them by our down spouts to give them extra water. This year I had more insect activity than ever. I’ve had Butterfly Weed for years and have not had much luck attracting Monarchs .That all changed with the Swamp Milkweeds.

    • says

      Hi Mike, glad to hear adding more varieties of milkweed brought more monarchs to your garden. This was a banner year for swamp with cooler temps and more rain in the upper midwest. You’ll find that “favorite” milkweeds change from year to year depending on the weather patterns. There were also more monarchs this season too…I hope this trend continues going forward. Congrats on your swamp success!

  4. Charlene Cornett says

    I’m so glad I found this website. This is my second year raising butterflies and have found this site very informative. I have the perfect moist spot for swamp milkweed. now that I know – that will be my new project.

    I have a large area of common milk weed and hoped to harvest the seed but have lost most to aphids and beetles. Other than hand clean the pods what else could I be doing to save more seed? Black birds do a wonderful job of cleaning when they come in a flock , but you know how they are–here today, gone tomorrow.

    • says

      Hi Charlene, I’m happy to hear you have taken up the hobby of raising monarchs…a fun and rewarding experience. Aphids and beetles can be pests, but I usually try to combat pests by diversifying milkweed varieties and putting several patches throughout the yard and garden.

      If you feel you need to remove beetles, you could always flick them in a bucket of soapy water, which works well for Japanese beetles. Otherwise, I think birds eat them too. Here are 7 ways to get rid of aphids…good luck!

      Stop Aphids from taking Over your Milkweed

  5. Brian says

    Hi Tony,

    We have been butterfly gardening for a few years now, and I just read that swamp milkweed has an average lifespan of 3 to 5 years. We haven’t lost any of our plants yet, but this will be the fourth year for our original swamp milkweed and I wonder if I should start a few new plants from seed this spring just in case we start losing our original plants in the next year or so?

    Have you had to replace any of your swamp milkweed, or have your plants lived longer than the average 3 to 5 year life expectancy.

    Thanks.

  6. Sheila Spotswood says

    I saw a mention on another list of features of swamp milkweed that it could grow in a swamp or pond. Do you know if we could actually grow it submerged in a pot in a pond with a plastic liner, no swamp or wetland type edge. Full or maybe filtered late afternoon shade, depending on where we put it. We’re adding more local milkweeds in sunny ground areas, and I love the idea of some pretty pink ones in the pond.

    • says

      Hi Sheila, I haven’t personally grown it in water, but it’s in a section of our yard where there is often standing water after snow melt and after heavy rain. I’ve also seen it growing right next to lakes/ponds where I’m certain it must be submerged during wetter periods. I would try a few and see what happens…please keep us posted!

  7. Mary Reilly says

    I am growing a butterfly garden for a few years now. Last year I planted swamp milkweed asclepias incarnata. I have saved lots of seeds and also threw lots of seeds back in the garden. I am new to this. I want to buy more milkweed different varieties annd plant but no one seems to carry it on Long Island. So where can I buy it? Also what varieties? Last year had lots of problems with aphids . I cut down plants to ground. Will they grow again?

    • says

      Hi Mary,

      if you can’t find any good local resources, check out my resources page for milkweed seeds and plants. The page also lists native regions and perennial zones to give you some ideas:

      25+ Milkweed Ideas for Butterfly Gardens

      Swamp milkweed is pretty resilient so I would be hopeful it will come back this season, even after cutting it back. Good luck!

  8. Holly says

    I like the purplish color of the Swamp Milkweed shown in these pictures. Where can I get seeds that will produce this color of plant? Also, I’m in upstate NY and my Asclepias Tuberosa dies out here in the winter. Other people write as though it lives through the winter. Am I missing something? I grew tuberosa in Santa Monica CA and it lived through winters, along with Monarchs that graced my garden year-round. I’ve been trying to find out which Ascelpias species will live through the winters in upstate NY. Any advice would be appreciated. Thanks!

  9. Tammy Potte says

    I have swamp growing from rhizomes. So if I read these posts correctly, seeds do better in pots and rhizomes do better in the ground. last year we had no luck with the seeds, but this year I bought a rhizome and it just took off.

    • says

      Hi Tammy, swamp milkweed doesn’t have rhizomes…just a regular root system. This makes it an easy milkweed to transplant in your garden or in containers. You can try growing any variety of milkweed in containers. If the variety spreads through rhizomes, you’ll want a bigger pot to accommodate them.

  10. Kat Rugar says

    I bought a swamp milkweed plant last year and planted it in a sunny
    spot in my Richmond, VA garden. To my surprise, it is growing strong
    this spring. Can I divide this plant, or take a cutting, to increase my
    plants?
    If I can take a cutting, can I use the tropical milkweed instructions?

  11. Barbara Bonforte says

    I’ve been raising monarchs for over ten years…I recently bought swamp milkweed and am wondering if it will grow well and survive a New Jersey winter if I plant it in pots rather than in the ground. A friend told me it would not flower in a pot and that it would not survive the cold of winter. Please advise.

    • says

      Hi Barbara, swamp milkweed will bloom in containers if it’s a second year plant or older. We don’t overwinter swamp in pots, we leave a few seedlings in undesirable places, and then pot them up when they return next spring. You can also keep them in pots. I would advise putting containers in a protected area or wrapping the pots to keep soil temps warmer until spring.

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