Milkweed and Monarch Concerns – 2015

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January 18, 1996, when Clay and I visited the El Rosario winter roost in Mexico. That winter the population estimate was 631 million Monarchs

The final fall generation of Monarchs empties out of southern Canada and the United States east of the Rockies and migrates to the mountains of Mexico. This overwintering population is estimated each December. December 2014’s estimate was 57 million Monarchs in Mexico’s mountain top roost sites. Sounds like a lot of Monarchs, doesn’t it? But the harsh reality is that the December 2014 population was 80% below the long-term average of 300 million Monarchs.

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January 1996 the overwintering Monarchs covered 12.61 hectares (or 31.2 acres). I was in heaven as they landed on me as if I was one more shrub in the forest

The December 2014 overwintering Monarchs covered just 1.13 hectares (or 2.79 acres). This doesn’t sound like such a large area, does it? The Monarchs that covered these 2.79 acres in the mountains of Mexico are the core group that will repopulate the United States and southern Canada east of the Rockies in 2015.

Once it warms up in late February, Monarchs mate at the roost sites in Mexico where they have overwintered. By the second week in March they leave the roost sites and journey north. Females, full of fertile eggs, lay their eggs along the way on emerging milkweed. They begin arriving all along the Gulf Coast (Texas, Louisiana, Alabama, Florida) in late March and early April. Each returning female lays about 600 eggs on southern milkweeds.

From egg to adult Monarch takes about one month (or longer if it is a cold spring). So one month later the first generation (the children of the overwintering Monarchs) migrates further north, seeking and laying eggs on Milkweed as they go. This hop-scotch north is accomplished by multiple generations until they finally reach southern Canada, the northern limit of milkweed’s range.

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White Milkweed (Asclepias variegata) in the woodlands near Chattanooga, Tennessee, with a Diana Fritillary


No matter where you live, let’s be ready for 2015’s Monarchs. Plant milkweed with a vengeance so that the Monarch population can swell generation by generation over the summer and fall months. They need all the help we can give them. At Cape May, NJ, we see the first Monarchs sometime from mid-April to mid-May, just as milkweed is poking through the ground.

There are 108-110 milkweed species native to the United States and Canada. Monarchs use ONLY 27 of these as host plants.

With the combination of (1) Monarchs in the news, (2) growing concern to use native plants in landscaping, and (3) more and more native plant nurseries on the scene, it is now possible to find and plant a healthy selection of some of these 27 milkweed species.

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A meadow of Butterfly Weed (Asclepias tuberosa) also known as Railroad Annie because it can thrive in dry, sterile soils


Monarch Joint Venture’s “Plant Milkweed for Monarchs Fact Sheet” showcases milkweed species found region-by-region and includes 20 different species.

Monarch Watch’s “Bring Back the Monarchs” campaign also highlights these 20 species with in-depth fact sheets and photos, helping gardeners understand which ones are native to their area and where to plant them (i.e. where they will flourish: in a well drained spot, a damp spot, a woodland, a prairie).

Also read my posts “Milkweeds for Monarchs” and “Monarch Migration at Cape May: Fall 2012.”

If you are lucky enough to have a native plant nursery near where you live, purchase and plant the native milkweeds found in your area in your gardens and meadows. Plant at least 3 of each species in groupings. Perennials will spread over time so the end result will be massed plantings or islands of milkweed. Scatter plantings around your property. In some spots they will flourish, in other spots they may not. By planting groupings of milkweed in a number of places, the plants will tell you where they are happiest.


Monarch Watch’s “Bring Back the Monarchs” Milkweed Plant and Seed Suppliers
Xerces Society’s Milkweed Seed Finder
Monarch Joint Venture’s “Create Habitat for Monarchs”
Monarch Watch’s Milkweed Seed Kit

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Make sure your garden is a dinner table full of healthy stands of nectar and Milkweed spring through fall


Milkweed is essential for Monarchs to create the next generation, but they also need nectar spring through late fall. Plant native perennials known to be favorites with pollinators and plant them agressively! This website is jam packed with excellent articles and ideas all about that.  The Pollinator Partnership’s region by region Pollinator Friendly Planting Guides are also priceless. If you live in the Northeast, my article “How to Create a Butterfly and Hummingbird Garden” shares many helpful tips and includes a list of recommended nectar and caterpillar plants. The list and article contain Butterfly Bush, which I would never include today (because it has been proven to be invasive) so put a big black line through Butterfly Bush and instead plant the many other suggested native perennials.


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Ro Wilson’s cherished Common Milkweed patch coming up where it pleased

    • We can educate anyone who will listen (and maybe some who won’t) to see milkweed not as a weed but instead as a lovely native wildflower crucial to the Monarch’s future and the future of all pollinators.
    • We can nudge, suggest, or even demand that stands of milkweed and other native wildflowers be spared by repeated roadshoulder mowing regimes. We can all work towards more wildflower-friendly roadshoulders, especially the stretch beyond the first 3 to 5 feet that do need to be mowed for safety sake. Do we need 15 to 20 feet of mowed edge along highways? No! See if there is already a program in your area where you can adopt and sign a roadside stretch so that the area is only mowed once a year in late winter, allowing wildflowers to grow, flower, and set seed naturally the rest of the year.
    • We can urge educators to incorporate schoolyard habitats into their curriculum, places where milkweed and other host plants and pollinator plants can flourish and benefit Monarchs and other pollinators and become outdoor classrooms of learning. This learning experience would be real, life giving, high impact, and crucial to pollinators like Monarchs – far better than ordering Painted Lady kits through the mail as some behind-the-times teachers still do.
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Imagine if wildlife management area fields offered a profusion of Butterfly Weed and Common Milkweed

  • We can urge our state wildlife management areas to manage their successional fields for native plants by battling the invasive non-native grasses, lespedeza, vines, and multiflora rose thickets that have out-competed native wildfowers and grasses. With some effort these fields could be havens of Butterfly Weed and Common Milkweed.
  • We can stop frequenting nurseries that carry problem plants like the very invasives that have spread into our natural areas and wildlife management areas and are crowding out native species. We can support native plant nurseries and native plant sales organized by non-profits.
  • We can work to educate and convince those who have acres of mowed lawn to instead consider wildflower meadows full of milkweed and other pollinator plants and host plants. Great tutorials are available in Catherine Zimmerman’s excellent book and DVD, Urban and Suburban Meadows, and through her latest project, Hometown Habitat.


The Monarch’s complex decline is succinctly explained by Journey North. Be sure to read through it and all the links.  I shared some of the issues in my post, Where are the Monarchs?

Read and understand OE, Ophryocystis elektroscirrha, a protozoan parasite that is infecting Monarchs and Queens. Learn that OE spores live on and persist on Tropical Milkweed where this non-native plant has become perennial, infecting healthy Monarchs as they land on it to lay eggs or nectar. Anyone living where Tropical Milkweed is now perennial should NOT plant it or cut it to the ground in winter to eliminate any OE spores.


Recently, our local paper (the Press of Atlantic City in New Jersey) had fun pointing the finger at wildlife gardeners as being part of the Monarch free fall, claiming that well-intentioned wildlife gardeners who have planted Tropical Milkweed, “may actually be killing Monarchs.” The Press certainly stirred the pot. My phone buzzed. My e-mail box overflowed. Nurseries wanted to know if they should grow it. Gardeners wanted to know if they should plant it.

Indeed, if you live in Florida, Georgia, South Carolina, Tennessee, Louisiana, Texas, and some coastal areas of southern California, where Tropical Milkweed survives the winter, you should NOT plant Tropical Milkweed. OE spores can survive on Tropical Milkweed through winter months and can cripple or kill healthy Monarchs that come in contact with the OE spores on those plants.

These two excellent article explain this serious threat in areas where Tropical Milkweed has become a perennial:

  1. Tropical Milkweed: To Plant it or Not, It’s Not a Simple Question
  2. Native Habitats for Monarch Butterflies in South Florida
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Monarchs will lay their eggs on Common Milkweed late into the fall, so leave it standing even when it looks gnarly

Once you’ve planted all the milkweeds native to your area that are suited to your site, then consider complimenting them with the annual Tropical Milkweed if and only if you live where it is not perennial. Here in southern New Jersey Tropical Milkweed is an annual, dies back after the first frost, and must be planted from seed each spring. So it can not harbor OE over the winter. Another argument that some claim is that Tropical Milkweed is keeping Monarchs here later than normal in the fall. Common Milkweed is still in leaf late in the fall and I have found Monarch eggs and caterpillars on Common Milkweed in early November. That being the case, Tropical Milkweed can not be said to be keeping Monarchs here any later than the native Common Milkweed is keeping Monarchs here.  Instead here in South Jersey and other places where it is not perennial, annual Tropical Milkweed serves only as additional nectar and host plant material.

Let’s all work together to do what we can to save Monarchs. A population 80% below the long-term average, and covering only a paltry 2.79 acres, is a true crisis we need to respond to.

Pat Sutton, of Cape May NJ, is an author, educator, and naturalist who has taught gardening for wildlife workshops and led tours of private wildlife gardens for over 30 years. She shares her passion around the country at festivals and conferences and is available to speak to your group or organization.

© 2015, Pat Sutton. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. We have received many requests to reprint our work. Our policy is that you are free to use a short excerpt which must give proper credit to the author, and must include a link back to the original post on our site. Please use the contact form above if you have any questions.

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  1. Annette Tyler says

    This is the article I found in the StarLedger about monarchs and milkweed.

    By Valerie Sudol
    Email the author
    on March 13, 2015 at 6:00 AM, updated March 13, 2015 at 6:05 AM

    Monarch butterfly populations are down across the country and the National Wildlife Federation (NWF) thinks kids should do something about it.
    Earlier this month, the NWF launched its Butterfly Hero Campaign to encourage youngsters and their families to plant milkweed, a plant that is the exclusive and essential food of the monarch caterpillar. The first 10,000 to register get a free kit with native milkweed seeds and the winner of a drawing gets a trip to Disney World in Orlando, Florida.
    Entrants are asked to submit a photo of themselves (or their young person) making the sign of the butterfly as per international sign language. You’ll see exactly how in photos on the web, where entry forms and rules are also available.
    Monarchs are famous for their long-distance migrations, a wonder of the natural world. Females lay their eggs exclusively on milkweed plants so that their young, ingesting the mildly poisonous sap, develop a terrible taste that discourages predators from eating them.
    Degrading habitat along their North American range and logging near their wintering grounds in Mexico are largely blamed for the monarch’s population decline. But without milkweed, these beautiful insects are nowhere.

    • Pat Sutton says

      This is a great first step. Let’s hope that these youngsters and their families embrace gardening for pollinators by (1) carving out chunks of lawn area for garden beds of milkweed and additional nectar plants, (2) send chem lawn companies away, (3) don’t spray insecticides, (4) take time to monitor what their new gardens attract and benefit, and (5) get hooked and eagerly add to pollinator garden beds year-by-year!
      Pat Sutton recently posted..Monarchs and Milkweed in 2015

  2. Brian Tremback says

    Besides using species native to one’s area, are there species more favored by monarchs than others? Does it matter if we just use the native ones we find most attractive, or should we try for diversity?

    • Pat Sutton says

      Brian, despite there being 27 Milkweed species that Monarchs use as caterpillar plants, only 5 are recommended for the Northeast region, 3 for the South Central Region, 5 for the Southeast region, etc. in Monarch Joint Venture’s “Plant Milkweed for Monarchs Fact Sheet” and Monarch Watch’s “Bring Back the Monarchs” campaign that I shared links to in my post. To ensure that Monarchs have the correct plant to lay their eggs on, you’ll want to focus on the species recommended for your region. Beyond that, whatever you plant in addition is up to you. The more nectar the merrier, but by focusing on these important milkweeds you’ll be guaranteeing that Monarchs have the correct plants to lay their eggs on to create the next generation.

  3. LYNNE TARVES says


    • Patricia Sutton says

      Lynne, I’ll bet your meadows would be great places for both Butterfly Weed and Common Milkweed stands. Thanks for sharing the post with anyone who will listen!
      Patricia Sutton recently posted..Monarchs and Milkweed in 2015

  4. Susan Campbell says

    Hi Pat,
    I am residing in central Florida most of the year. This past fall I purchased a “yellow” milkweed from a plant fair. It had no other description. I harvested some seeds and cold stratified them in the refrigerator. Your articles sound like it would be safe to plant them in NJ. Is this true? I am here now and would not want to hurt any monarchs.
    Please let me know.

    • Pat Sutton says

      Hi Sue, GREAT question! I’ll bet that the milkweed you purchased at a craft fair in Florida is Tropical Milkweed, the yellow variety (just GOOGLE yellow Tropical Milkweed and scroll through all the photos and let me know if the photos look like your milkweed). See Loret’s comment below about a great native plant sale in mid-April in Central Florida including native milkweeds. Sale’s like the one Loret mentioned are probably where we all want to purchase our milkweeds so we know exactly what we’re buying. There is no milkweed called “Yellow Milkweed.” For sellers NOT to let buyers know exactly what they’re buying (especially if it is Tropical Milkweed and the location is Florida) is not very responsible. If the photos do help you match it to Tropical Milkweed, you’ll probably want to replace it with a FL native milkweed.

      For your NJ home garden it would be OK to plant it (since Tropical Milkweed is an annual in NJ), but you’ll also want to take advantage of all the great native plant nurseries and native plant sales and invest in some of the native perennial milkweeds that grow in NJ (Swamp Milkweed, Butterfly Weed, Common Milkweed, Whorled Milkweed) if you don’t already have them.

      Again, thanks for sharing this GREAT question. I’ll bet there are many others in positions like yours who have purchased “Yellow Milkweed” in similar venues without realizing that it is Tropical Milkweed.

      Happy Gardening! Pat
      Pat Sutton recently posted..Monarchs and Milkweed in 2015

  5. Loret says

    Outstanding article Pat. Floridians, please heed the warnings re: tropical milkweed.

    And for those of you in Central Florida, April 10-11 There is a all native plant sale planned in Kissimmee by four chapters of the non-profit Florida Native Plant Society. A wide varierty of plants for all conditions, including more than one hundred native milkweed plants will be available for purchase. Come early! These plants sell out quickly.

    Thanks for all you do Pat. Awareness is so important.
    Loret recently posted..Asclepias incarnata (SWAMP MILKWEED)

    • Patricia Sutton says

      Loret, thank you SO MUCH for sharing the Central Florida Plant Sale information where native milkweed plants will be available for sale. Excellent! May the sale be a huge success, help people who want to plant the right plants for Monarchs, serve as a great education to Floridians why NOT to plant Tropical Milkweed, and be a great fund raiser for the non-profit Florida Native Plant Society. Keep up your great work! Pat
      Patricia Sutton recently posted..Monarchs and Milkweed in 2015

  6. Michele says

    Thank you for the “get a grip” comments about tropical milkweed! It only makes sense to plant the species of milkweed native to your area and areas that the non-native tropical flourishes should certainly avoid it out of commonsense. I live in Illinois – it does not survive the winter here. I plant it in containers because it is a useful source of food late in the season when my other milkweed crops are dying back or decimated by the very reason for them being there.

    Great article in many ways – thank you!

  7. Anne Clark says

    Great article Pat! I love all the detail and links you provided. I was encouraged yesterday on this note…one of my landscape design clients contact me to have me add more butterfly weed in his garden! Collaboration and awareness campaigns are making an impact :)
    Anne Clark recently posted..Bringing Your Garden to Life

    • Pat Sutton says

      Terrific! When clients come to you and WANT milkweed (a weed to so many . . . sadly), this is indeed a good thing.
      Pat Sutton recently posted..Monarchs and Milkweed in 2015

  8. Marilyn says

    Thanks to you and others on this website, I was encouraged to locate and plant Asclepias tuberosa last year. We were were there when the gates opened on the native plant sale, and went directly to the section where the milkweed was being sold–arriving just moments an before an elderly gentleman who was looking for the same thing. We shared the few plants that were there and brought home 6 scraggly plants which we did not think would even live but did wonderfully well. I couldn’t help wondering how many other people who were looking for milkweed went away empty-handed. The word is getting out.

    • Pat Sutton says

      Marilyn, I LOVE what you shared! Thank you. So many folks that are new to native plants are initially put off by how they don’t SHINE during spring sales next to non-native plants that have been forced into a shimmering, alluring, dazzling,irresistible blooming show piece. YES, once you embrace native plants you learn to be patient and trusting that the tiny, unassuming plant will indeed become a plant of wonder and beauty drawing in amazing pollinators (including Monarchs), while that eye-catching non-native just takes up space. I have bought many a scraggly plant that turned into some of my most favorite garden plants. Patience and trust. Happy Wildlife Gardening! Pat
      Pat Sutton recently posted..Monarchs and Milkweed in 2015

  9. Beatriz Moisset says

    You covered a lot of ground in just one article. Indeed, it is a complex subject. Ah! Some of the paradoxes about monarchs and milkweeds! We should all remember that there are other monarchs in addition to the migratory ones. Danaus plexippus plexippus is just one subspecies, the one that travels from Mexico or California to Canada. But there are 5 or 6 subspecies distributed in the Caribbean, Central America and northern South America. They are not migratory, or not as much. I assume that the more tropical monarchs feed on tropical milkweed year round and survive regardless of OE. I wish somebody would bother to study this issue and let us know.

    We also don’t know the total numbers of monarchs a century or two ago. Curiously, for a number of years, farmland was ideal for monarchs. Common milkweed grew well between cultivated rows and along field edges. Seventy percent of these butterflies arriving in Mexico had been bred in farmland. So, it is possible that farming, and also deforestation in the East, benefited monarch butterflies. Probably we will never know.

    I find the idea of planting non-native tropical milkweed disturbing. Not just where it can cause problems due to OE but anywhere where it is not native. Those who don’t care about conservation can go ahead planting non-native milkweeds and butterfly bush, as well as tulips, roses and Japanese maple. They garden for their own satisfaction and not for any ecological reasons.

    But those of us with ecological concerns should care about conservation of all creatures and conservation of habitats, not just of one species that happens to be charismatic. Every time we plant a non-native plant, we are taking space that could benefit some other plant species also in need of space. Worse yet, in many instances the non-native plant may end up causing troubles of a different kind by becoming invasive or by carrying an invasive pathogen of one kind or another. Many non-native species don’t present these problems yet, but every one of them has this potential. It can take as long as a century, but it could happen. Granted that the probabilities are low, but when it does happen the consequences can be devastating.

    This is why I can’t find a justification for resorting to tropical milkweed. If the particular habitat doesn’t support enough milkweeds, maybe it is not meant to be. We must remember that not all areas are equal when it comes to growing milkweeds and to monarch conservation. The biggest losses have occurred in Texas and the Midwest. This is where more milkweeds are needed. In my area, for instance, it is not the milkweeds, but the monarchs, that are missing. They don’t come because the previous generations didn’t make it for lack of milkweed in the two areas mentioned, Texas and the Midwest.
    Beatriz Moisset recently posted..Mass Appeal and Pollination

    • Pat Sutton says

      Beatriz, thank you for your words of wisdom. Along with a wealth of native plants, I’ve always saved room in my garden for “Chocolate Cake” annuals since they are the energizer bunnies of the nectar world, offering nectar from early summer until the frost. Some of my favorites and favorites with pollinators are: Zinnias, Mexican Sunflower, Tropical Sage, Cardinal Climber, Cuphea David Verity, and Tropical Milkweed. As long as these non-natives remain annuals here in South Jersey I’ll continue to compliment my nectar offerings with them. I am so fortunate to have a sizable garden where I’ve planted and / or nurtured 100s of natives that are serving as bird food (berries, seeds, cones, catkins, caterpillar plants), caterpillar plants / host plants, nectar plants . . .

      The materials shared in my post (via links) including recommended native Milkweeds for Texas, the Mid-west, etc., as well as all the nurseries and non-profits that are promoting planting of these milkweeds for distribution is stellar work. To a path of native milkweeds from Mexico to Canada and back! Again, thanks for your heartfelt thoughts.
      Pat Sutton recently posted..Monarchs and Milkweed in 2015

  10. Lorna Wooldridge says

    Very nice article Pat. I just shared it on through my Facebook page. Looking forward to seeing you on Sunday.



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