Asclepias Incarnata

Swamp Milkweed for Monarch Butterflies
and Caterpillars

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

Swamp Milkweed Flowers
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

Swamp Growing Tips:

  • Slow release fertilizer is optional. Over-fertilization can inhibit flowering
  • 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:

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

18+ Milkweed Plants 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

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