Asclepias Curassavica

Tropical Milkweed for Monarch Caterpillars…
and Butterflies!

Asclepias curassavica: Tropical milkweed, Mexican milkweed, Scarlet milkweed, Bloodflower, Swallow-wort, Silkweed

Tropical Milkweed for monarch caterpillars and butterflies
Tropical Beauty

Plant Specs:

  • Perennial: USDA hardiness zones 8a-11 (lows -12.2 °C or 10 °F)
  • Annual for zones below 8a
  • Full sun to part shade
  • Height: 2 to 3 feet
  • Spacing: 1 to 2 ft
  • Flowers: red and yellow, ‘silky gold’
Monarch Female Laying Eggs on Silky Gold Tropical Milkweed
Baby Bump

Pros:

  • Top plant for monarch egg laying
  • Monarch butterflies and others use as a nectar source
  • A favorite source of nectar fuel for the monarch migration
  • Showy red and yellow blossoms all summer
  • Seeding is not an issue in annual zones
  • Easy to transplant
  • Deer and rabbit resistant
  • Can Still flower while it produces seed- Blooms all season
Asclepias curassavica Buds, Flowers, and Seedpods growing at the same time.
The Multitasking Milkweed…Blooms While Seeding!

Cons:

  • In northern zones, must start seeds indoors to reach full maturity
  • The flowers also attract wasps but they haven’t been aggressive
  • Aphids can be bothersome

Plant Propagation:

  • Start seeds indoors 2 months before final frost
  • Sow seeds directly after final frost (not recommended below zone USDA zone 8)
  • Soak seeds in warm water 24 hours before planting
  • Stem cuttings- easily root in water
'Silky Gold' Tropical Milkweed has just as much Monarch Appeal as the Original Tropical Variety.
A Cultivar with Butterfly Appeal

Tropical Growing Tips:

  • Start cuttings or buy plants for full season bloom period
  • Lusher leaves in partial shade.
  • Taking cuttings at season’s end to place in water overwinter
  • Collect seed pods as they start to crack open
  • Plants can be overwintered indoors
  • Southern California, Florida and Texas gardeners should consider cutting back tropical plants to the ground in fall to cut down the spread of OE and to encourage the monarchs to finish their fall migration.
Eastern Tiger Swallowtail Tropical Milkweed
Tropical Tiger

Pollinator Plus:

This milkweed also attracts eastern tiger swallowtailsgiant swallowtails, hummingbirds, painted ladies, pipevine swallowtails, queens, wasps, and more…(If you know other pollinators tropical milkweed attracts, please comment below.)

Resources:

1.

Click here for 25+ Milkweed Ideas for your Butterfly Garden

Please post below if you have any questions, comments, or suggestions for growing Asclepias curassavica in your garden:
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Comments

  1. Sarah Black says

    I am wondering when you usually do your cuttings of the milkweed. I have plans to create an enclosed butterfly pavillion and a butterfly garden.

    • says

      Hi Sarah, if you want mature tropical milkweed at the beginning of next spring, I would suggest fall cuttings. If you bring plants indoors to overwinter, you can take cuttings a couple months before your average last frost. This gives you a huge head start on the season. I will be posting about fall cuttings in late August or September. Good luck with your new garden and pavilion, Tony

  2. says

    Tony,
    Nice butterfly pictures and we should also be getting our first freeze as well during same time as you. Received some A. Curassavica seeds and have 3 seedlings coming undergrowth light in the basement so excited, each day its seems one more pops up planted 15 seeds and using my tiny warmer as well. Also have seeds of A. Purpurasens and Asperula know both need cold/moist stratification. Would it be beneficial if they had some additional time in a cool fridge without the moist stratification prior to giving them moist stratification? Thanks for all you insights. Brian

    • says

      Hi Brian,

      I’m not sure that starting perennial seeds indoors at this point is a good idea. Tropical milkweed can be started now because it doesn’t have a specific bloom period and you’ll have mature flowering plants the entire summer.

      Purpurascens and Asperula have bloom periods and I’m not sure how growing them all winter would affect that. You would be better off starting those seeds about 2 months before your average final frost in late winter. You could also winter sow them by planting them directly or keeping them in containers outside:

      http://faq.gardenweb.com/faq/lists/wtrsow/2002050141031613.html

      As for cold stratification, all I have ever done is put seeds in the refrigerator for a few weeks. I leave them in their packaging and put them inside a plastic bag in case something were to leak. This has always given me great germination results for milkweed. Hope this helps…

  3. x says

    > “If you know other pollinators tropical milkweed attracts, please comment”

    Bees, of course. Zebra Longwing, Gulf Fritillary, Cloudless Sulphur.

  4. Toby says

    Hi there I am living in the Tropical South Pacific and have purchased A. Currassavica seeds but have had a really poor germination rate. I have bought a potting mix because not to sure on the quality of the soil in the Garden but still there not germinating well. They are planted in seed trays, and are on table under an open garage. There is a spot light that comes on automaticslly after it goes dark is this something that can affect the germination. If you have ideas please reply ok many thanks

    • says

      Hi Toby, I soak my tropical milkweed seeds in warm water for 24 hours before planting them. You can keep the water at a good temperature by putting the seeds in a small bowl of water and placing it on a heated seedling mat. After you plant the seeds the heated seedling mat can also be used to speed up germination. You don’t need to use the spot light if they are getting light during the day. Our seedlings get about 10 hours of light. Check out this article for more info:

      http://www.monarchbutterflygarden.net/starting-seeds-inside/

  5. Wam'z says

    Hi,
    I just wanted to know how long it takes for the milkweed to mature from the cuttings when grown under Hydroponic planting method.

    • says

      Hi, I just grow them until they root and then plant them in-ground. This typically takes between 1-2 months. The system I tried to root them this season was not successful and the styrofoam inserts were causing them to rot, so I switched back to placing them in a glass of water (but this time using distilled water) and placed the glasses o my heated seedling mat.

      If you’re looking for rapid growth and full size plants, someone just sent me this info which might help:
      http://www.folksbutterflyfarm.com/aeroponics_tote.pdf

  6. Chris Hammond says

    If you live in the United States please read the following article before deciding to plant Asclepias Curassavica (Tropical Milkweed). Unfortunately, this well-intentioned effort to restore habitat may actually be contributing to the decline of the Monarch population. It is important to plant only Milkweed species that are native to your area. The article links to helpful sites that can guide you to the correct selection.

    http://blogs.kqed.org/science/2014/11/19/efforts-to-restore-monarch-butterflies-milkweed-habitats-may-be-doing-more-harm-than-good/

    • says

      Chris, this article is based largely on speculation with little science to back it up. Too many people are focused on the potential negatives of tropical milkweed when there are simple solutions for dealing with some of these problems like cutting back milkweed (to avoid overuse) for those in warm weather regions. Also, we have viable tropical milkweed in our northern garden for weeks after the monarchs are gone. If the milkweed was their cue for leaving, they’d be leaving much later. Tropical milkweed grows quickly and is a favorite egg laying milkweed for monarch butterflies. It has even been shown to have medicinal qualities that help produce healthier monarch butterflies compared to native varieties of milkweed:

      Emory University Research

      Before we start spreading speculation as truth, there needs to be more research. For now, tropical milkweed will remain one of many (both native and non-native) milkweed varieties we grow in our garden.

  7. Deborah Brooks says

    I have a container garden on my garage roof in San Francisco, CA. I wanted to buy native milkweed to help the monarch butterflies, but was advised that CA native milkweeds would need very large containers because their roots need to go very deep. I can’t have really large containers on the roof because of their weight. But I was told that it didn’t matter, since monarch butterflies don’t breed in SF anyway. At another nursery, I was told that I should get some A. Currassavica because the butterflies at least are attracted to them for their nectar. Now I’m worried that I’m disrupting their migration. At what point should I bring the plants indoors? Is it already too late? The temperatures are still mild (low to mid-60s) and I still see a few monarchs.

    • says

      Hi Deborah, it’s too late for monarch eggs this season. If you bought curassavica now would be a great time to cut it back. There is no conclusive evidence that tropical milkweed is disrupting the migration. Where it is most likely effecting monarchs is in warm weather regions where it grows all year and monarchs could overwinter. Monarchs do breed in SF…but not this time of the year.

      Tropical and swamp milkweed both grow well in containers. If you’re looking for a California native, you might try tuberosa, but it’s not a preferred milkweed species for laying eggs. Here’s my milkweed resources page for more info:

      Milkweed on MonarchButterflyGarden.net

      • Bill says

        I’m surprised that you say A. Tuberosa is not a preferred milkweed for Monarchs. It’s the only species I can find at the nurseries here in Los Angeles, and when I planted 6 of them they were soon hosting dozens of caterpillars. The plants were quickly stripped of their leaves and the cats grew large. I didn’t see a single chrysalis on any plant, but I sighted several Monarchs flitting about. This year I bought a mesh cage and moved 5 cats inside, along with cuttings of A. Tuberosa in water, which I kept replenishing. Each of the 5 has become a chrysalis, so with luck I’ll have 5 Monarchs to release. At least for this area, A. Tuberosa seems to be preferred.

        • says

          Hi Bill, it’s all about supply and demand. If they have other options available, tuberosa isn’t typically the plant they go for because of the coarse, sapless leaves.

          Are you talking about tropical milkweed (A. curassavica) or butterfly weed (A. tuberosa)?

  8. Ginny Reeves says

    I live in Houston and have been raising Monarchs for a couple of years now. This is the first time I have seen so many cats on my milkweed in December. Should I be cutting down the milkweed earlier? I just had17 butterflies I had to let go outside (not optimal weather).

    • says

      Hi Ginny…typically the migration is over at the beginning of November, but things went a little late this season. I would suggest that would be a good time to cut back tropical milkweed plants. I try to release monarchs monarchs when it’s at least 60 and sunny to give them the best chance for survival. Here some info that might help for future monarchs:

      Releasing Monarch Butterflies

  9. Jesi says

    I just bought these seeds and I’m planning on planting them in Puerto Rico. Should I follow the same instructions? Wet my seeds overnight and plant them in the morning? I also got Swamp Milkweeds and Butterfly Milkweeds but I doubt I could grow those here.

    • says

      Hi Jesi, it never hurts to “try” as long as you are able to monitor the progress of your plants. Yes, no matter where you live i would suggest soaking the seeds first. It helps them to germinate faster. Please post back and let us know how your butterfly weed and swamp milkweed work out!

  10. Ron Doering says

    I agree with Tony’s comments on the unfounded hype about the so-called non-native species doing harm. We raise monarchs in SW Florida and our monarchs love curassavica. What environmental alarmists and what Tony calls native “purists” never explain is what they mean by native. I understand that we have over 100 species of milkweed now. What makes a species “native’? Is 1492 and the great Columbian exchange the date? If so, how do we know how many species we had then? At what time do we have a definitive list and how do we know that many if not most on that list didn’t come from the south. The whole concept of “native” is flawed. Perhaps all milkweeds were originally tropical. (thanks Tony for a great service to all monarch hobbyists)

    • says

      Hi Ron! Thanks for your comments. There are potential issues with growing tropical milkweed in regions where the plants don’t die back because of disease issues. However, instead of spreading hype and trying to alarm people, I wish more people would discuss viable solutions, because they exist!

      As for your native comments, I agree 100%. Sometimes I’ll look at the native map for a particular plant and see a state where it’s not native, surrounded by states where it is. This defies all logic and common sense, yet some believe these guidelines should be followed with question.

  11. Jeanine says

    I just bought some Asclepias Milkweed off the discount rack, they have blooms but look skimpy on the stems though they are tall, not much foliage on them. I live in Central Florida and it is March 1st now. Can I cut them back to make them fuller by next month or two or is it too late to cut them back? Also if I can cut them back, how far down do I cut them since it’s almost spring now? Thank you so much for your help in advance.

  12. Bob Carleton says

    We have 5 milkweed plants in containers. Over the past 2 weeks the caterpillars have eaten almost all of the leaves. We have seen several Monarchs landing on the few leaves this past week. The plants are about 1 year old. Should I cut then back or do nothing ? We are seeing several seed pods with some caterpillars eating them. Hope you can help!

    • says

      Hi Bob, in continuous growing regions it’s good to cut back a couple times a year to avoid the build up of OE spores that can potentially harm monarchs. You could try rotating plants so there is always some available while you cut back the others. If you have room, you might also consider growing more milkweed. 5 plants is just a snack for a hungry batch of monarchs…good luck!

  13. Joy says

    Hello,
    I am just learning about tropical milkweed. I have always planted the local varieties, but after watching Jaap de Roode’s talk on TED Talks. I would like to plant tropical milkweed if you think that is a wise choice for zone 7B in Virginia. My concern is that I already have problems with aphids, I try and control them by wiping them off the plant, but they are still a problem and I am so fearful of wiping off Lady bug lions and Monarch and other butterfly eggs. Can you offer any suggestions on how to control the aphids? Or should I just leave them alone since they only seem to bother the Milkweed?

    I also grow several varieties of Hyssop, Lantana, and Vitex–which I love because of all the different types of butterflies, moths, bees and wasps they attract–least I forget, the common housefly is a frequent visitor too. Thank you any information you can provide.

    • says

      Hi Joy, tropical milkweed is a great annual choice for butterfly gardens. It’s a popular host plant and provides nectar for monarchs during the fall migration.

      Check out my post on how to stop aphids from taking over you milkweed. The 3 best ways to stop them organically are milkweed diversification, having various patches around your yard/garden, and planting aphid repelling plants close to your milkweed. Here’s the full list:

      How to Stop Aphids from taking over your Milkweed Plants

  14. Carolyn says

    I have heard for last two or three years not to grow the Tropical Milkweed
    here in North Florida because it deformed the butterflies and also because
    it blooms so late they don’t do their natural migration. Now, after reading
    so many reports today, I am really confused.

    I cannot find any other milkweed locally that
    is not the tropical variety. Is it because growers don’t know Monarch difficulties, or it is easiest to grow? Should they be cutdown in early fall?

    Now I feel maybe I should return some beautiful plants I just bought at Lowes.

    • Tony Gomez says

      Hi Carolyn, tropical is easier to grow in Florida than other native varieties. Many gardeners also find it a more attractive option for their garden so that is driving demand. There are issues that need to be considered when growing it in your region. This article shares some precautions you can take to help avoid spreading monarch diseases.

      Tropical Milkweed and Monarch Butterflies

      As long as your plants were not treated with pesticides they should a fine addition for your butterfly garden, if you cut them back occasionally. Hope this helps!

  15. Amy Hammes says

    I really hate it when science comes out that counters mindsets and then we are all called “alarmists” for paying attention to it. Tony, I love your effort but I am really concerned that more native milkweeds are not being promoted here. Is this about our gardener preferences or about helping the species?

    The main concern is that although monarchs may LOVE this type of milkweed, they haven’t adapted to it. Humans love sugar and processed food but it doesn’t mean that we should be eating it, much less making it this much of a supplement of our diet. Tropical Milkweed being so prevalent is the “fast foodification” of Monarchs. We should be pushing for native species for YOUR REGION for many reasons, especially if that is the traditional food of these butterflies.

    If we have to fake the natural process and cut it back and fool the insects into moving on, that is making some big assumptions: 1) People are willing to do this type of maintenance and the appropriate timing 2) people will know they should be doing this (awareness) and 3) if the plant spreads to other areas, chances are they will not be cut back.

    What happens over time we discover that these “alarmists” were correct? What kind of damage have we done then? So silly when the solution is easy–plant natives.

    • says

      Amy, I couldn’t disagree more. First off, I’m not pushing tropical milkweed. My message is about attracting and supporting more monarch butterflies (and other pollinators) by diversifying your milkweed offerings….that includes both native and non-native varieties.

      I also believe in discussing viable solutions instead of dwelling on worst-case scenarios based on unsubstantiated theory…which is what being an alarmist is all about. I choose to focus on supporting healthy monarch butterflies for both our and future generations.

      • Amy Hammes says

        If being an alarmist is actually paying attention to what nature is telling us, then I think it is better than ignoring the obvious signs. That is what we call the Precautionary Principle.

        In short, the “precautionary principle” is a notion which supports taking protective action before there is complete scientific proof of a risk; that is, action should not be delayed simply because full scientific information is lacking. It shifts the burden of proof to the element, in this case the prolific planting of Tropical Milkweed, that IT is NOT harmful.

        Tropical Milkweed is pretty much all garden centers offer, with little to no instructions that it needs to be cut back. Also, the more this plant spreads, the more prevalent it will be and it will not always be cut back. Hence, that is the key that you are indeed promoting but it is missing many variables. So you are operating under huge assumptions that are impossible to control.

        I just wish you would discuss this issue as part of supporting healthy butterfly populations rather than writing it all off as “unsubstantiated”. That is very disingenuous.

    • says

      Hi Ernest, you can avoid overuse of tropical milkweed plants by cutting back your plants a couple times a season and letting healthy new growth emerge. If you are willing/able to do that, tropical milkweed can be a beneficial plant in your region. I would also suggest trying some California natives along with tropical to see what grows best and what attracts the most monarchs. Hope this helps:

      California Native Milkweed

  16. kc says

    I just planted the A. Tuberosa in a large container in my garden and now it looks a little sad. I’m confused as I thought this plant was hardy. I have one in the ground thats been cut back 3 times by the gardener in one year and keeps coming back. Why is the new plant not happy in it’s container? Could it be too hot? It is next to a wall in full sun most of the day. I want it to flourish. Thanks.

    • says

      Hi KC….if you’re talking about tuberosa, that variety spreads through underground rhizomes and can be problematic in containers if there’s not enough space to accommodate the roots. Also, if you don’t get the entire root when transplanting tuberosa this can stress the plant. You might try cutting back some of foliage if it’s not improving. good luck!

      If you’re talking about curassavica (tropical milkweed) try moving the container into partial shade.

  17. ReBecca says

    My grandfather collected seeds from his tropical milkweed and planted in a pot, a week after he gave it to me I see seedlings growing but today I noticed one seedlings first leaves are curling under, I live in Tampa bay area of Florida and wondering if there’s a problem with it. I have the pout outside on my porch where it gets plenty of sun and I only water when potting soil is dry, any suggestions?

    • says

      Hi ReBecca, if your tropical is getting full sun consider moving to partial sun. Also, it sounds like you could be under-watering so give your seedlings a bit more to drink. If you are fertilizing, I suggest waiting until the seedlings are more established. Good luck!

  18. ReBecca says

    My grandfather gave me some tropical milkweed seeds in a pot a few weeks ago, within a week they sprouted up, now 2 weeks later they are still only an inch tall and seem to stop growing. They are still green and no signs of distress. I have them on my porch where they get plenty of sun and I only water when potting soil is dry, why are they not getting any taller?

  19. ReBecca says

    Oops so sorry I didn’t see my first post when I scrolled down, thought it didn’t post the other day. I apologize for reposting. Thanks for the response.

  20. Betty says

    I just bought two plants at Home Depot a couple of weeks ago. One plant is just about to flower. Yesterday, I noticed the other one had a yellow, black and white striped caterpillars on it which I removed. Today I noticed several of theses caterpillars just eating away the leaves. Is there something I can do? Thank you

  21. says

    Hi Kate, in my opinion, that article is part of the problem because it only tells half truths and fills the rest in baseless theories.

    Many people are starting to believe that tropical milkweed is solely responsible for the spread of OE when the spores can be present on ANY milkweed variety, native or non-native.

    While there are potential problems with OE in warm regions, there are also simple solutions gardeners can take if they choose to grow it. The people that refuse to discuss those solutions aren’t doing the public, or the monarchs any favors.

  22. says

    Tropical milkweed is fine in its own habitat. Resident monarchs and many other tropical species feed on them and whether they get OE or not they must have worked that out during the process of coevolution.

    There is another issue we have to consider and this is what really matters. We need to save entire habitats, not just an individual species. Organizations engaged on conservation of monarch butterflies as well as conservation in general list only native milkweeds. It is important to use not just native milkweeds, but those native to your area. The following organizations provide lists of milkweeds and information on local suppliers and regional distribution of milkweed varieties. None of them mentions tropical milkweed for very good reasons. It doesn’t help preserve habitats where it is not native.

    Xerces Society Milkweed Seed Finder (25 native species and list of regional suppliers),
    Monarch Watch Milkweed Market (15 native species and regional maps),
    Monarch Joint Venture (about 20 native species by region),

    • says

      Beatriz, OE can be spread to monarchs through any variety of milkweed, both native/non-native. Yes, it’s more common on tropical milkweed in regions with a continuous growing season like southern California, south Florida, and South Texas but gardeners in most regions across the US don’t need to be concerned about this.

      I have never used this website to promote planting tropical milkweed at the expense of native milkweed, but to use it in combination with natives to support more monarchs throughout the season, which it does. Tropical milkweed also supports other pollinators in the local ecosystems of all regions, as you would realize if you had first hand experience growing it.

      The solution to supporting more monarchs and other pollinators will be found through the willingness to explore all potential opportunities, both old and new, to discover a better way to support pollinators in a modern world. Tony

    • says

      Hi Jesi, I”m not sure where you’re located, but I’ve never seen this growing tropical milkweed up north. It looks like it could be some type of fungus? If I ever have foliage issues on milkweed (which is rare) I remove the affected leaves and make sure I’m not overwatering the plants. I suggest contacting a gardening expert in your region to see if they have come across this. Please keep us posted and let us know if your plants recover…good luck!

  23. Don says

    Hi Tony,
    I just bought some starts of Asclepias Curassavica “Silky Deep Red”, and will be planting them in the coastal hills of Sonoma County, CA. I have big gopher and mole problems, and often have to plant in gopher baskets. Do gophers eat Blood Flower roots?
    Thanks!

    • says

      Hi Don, not that I’m aware of, but a few years ago I didn’t think deer ate milkweed…they most certainly do! I have never heard complaints of this, so I’m guessing it’s not a common issue. Sometimes, this depends on what other options you have to offer. We always make sure our bird feeders are full so the squirrels and chipmunks get their fill outside the garden. This has worked pretty well for us.

  24. Danica says

    I purchased 3 curassavica. I live in michigan 5b. I was wondering about how to over winter them or can I sow seeds directly in spring. I haven’t planted them yet and was wondering what would be the best site would be? Thank you.

    • says

      Hi Danica, once you have mature plants it’s much easier to overwinter and take cuttings to start new plants. They grow much faster than seeds. Here’s more info:

      Grow Tropical Milkweed from Cuttings For your planting- Tropical milkweed can be planted in full to partial sun in well-drained soil. Add compost if needed to increase soil quality.

  25. Claudia says

    What do you mean by cutting? Cut off the flowers? How much should one cut. I have a beautiful tropical-milkweed plant purchased 6 months ago and live in So.Cal. Thank you,

  26. says

    Hi Tony with a Y,
    You been mentioning a disease that tropicals and other milkweeds can get…what does it look like and how does it effect and does it effect the monarch in its transformation stages.
    I ask this because ive had some monarchs cacoon go grey or go black and dry up however I’ve seen others do just fine and i live in Southern California. Look forward to you getting back with me on that…O…also I have heard that the tropical plant doesn’t protect the monarch because it’s not toxic where as the native are….is this true.

    • says

      Hi Toni with an I,

      there are more disease issues in Southern California because the continuous growing season means plants can collect spores and bacteria. Here are some common monarch health issues:

      6 Monarch Diseases and Prevention

      Tropical milkweed actually has higher cardenolide levels than native milkweed, so it helps to protect monarchs. Keep in mind, many predators have adapted to the poisonous chemicals in milkweed, so it doesn’t keep them as safe as many people think….this is all milkweed both native and non-native.

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