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Should I Plant Milkweed to Save the Monarchs?

by on March 03, 2015

Monarch caterpillars devouring milkweed. Photo: Vicki DeLoach
Monarch caterpillars devouring milkweed. Photo: Vicki DeLoach

If you were a struggling insect beset by habitat loss, you’d best be a monarch butterfly. Unlike your more obscure cousins, you certainly wouldn’t slip into extinction without a bang.

In fact, we’re in a bit of a monarch mania at the moment as the population count continues to drop.

The Obama Administration recently tossed a cool $3.2 million to restore monarch butterfly habitat in the Midwest with the aim of getting the eastern population to a billion (fewer than 50 million monarchs made it to Mexico last winter). Meanwhile, the U.S. Fish and Wildlife Service has started a status review to see if monarchs deserve to be listed under the Endangered Species Act.

There’s even a movie out, Butterfly Town, USA, about the fight to save an overwintering site for western monarchs near the city center of Pacific Grove, California. (A free premier is showing April 2 in Palo Alto).

Butterfly Town USA – Film Trailer from Dorothy Fadiman on Vimeo.

All the attention has prompted monarch fans and environmental do-gooders to action. Perhaps the simplest thing to do is plant milkweed, an herbaceous perennial that’s the prime larval food source for monarchs. But it turns out that planting milkweed may not, in fact, always be the right thing to do to save monarchs.

Bay Nature put this question to local lepidopterist Liam O’Brien and the Xerces Society‘s Bay Area liaison, Mia Monroe (who is also site supervisor of Muir Woods National Monument).

With the monarch butterfly population in deep decline, should I plant milkweed in my garden?

Liam O'Brien

Liam O’Brien

O’Brien: The answer to this question seems more and more complex each day. People want an easy equation: Monarch + Milkweed = Saving Monarchs. Unfortunately in the Bay Area, we were inundated will a Goodwill tsunami of non-native tropical milkweed from Home Depot that went into everyone’s garden during the voguish years of “Butterfly Gardening” (70s-90s), so the question is not starting from a neutral base.

Turns out there is strong evidence that planting milkweed (Aesclepis sp.) in places it never was (San Francisco and other California counties) might not be the best idea. If they never bred somewhere, making them breed is not helping them. They should move along, or nectar, or overwinter in their South/Southwesterly Migration. Milkweed that never was is not missing. Get it?

So, this is what I would advise: a) Find out the local, native Milkweed endemic to your area. (Do not proceed to Home Depot because tropical milkweed is easier to buy. Do your research: call your local California Native Plant Society Chapter) b)  If you live in Northern San Mateo County or San Francisco County, DO NOT PLANT MILKWEED.

This may seem counterintuitive BUT THAT is actually helping the monarch. Contact the Xerces Society if you are not sure. Better to plant nectaring flowers in your garden if you are not sure. That will help them.

Is there a collapse in the numbers known for Monarchs in their migration? Yes. Is the solution more milkweed? Not sure. Greater folks than myself are studying it. Zealot commitment by the novice gardener must remain sound in science. Do not get caught up in The-Sky-Is-Falling-In-On-Monarchs hysteria. The Monarch, folks, isn’t going away anytime soon.

Mia Monroe at Muir Woods. Photo by Jacoba Charles.

Mia Monroe at Muir Woods. Photo by Jacoba Charles.

Monroe: Besides the basic premise of learning from nature, by doing the research, (i.e. don’t plant milkweed where it didn’t naturally grow AND plant the native species) Liam tucks in another universally solid suggestion: plant nectar plants!

Since planting native milkweeds is a helpful thing to do in parts of the Bay Area, the Xerces Society website is very helpful as they can help with identifying the right species, recommend sources, offer growing tips, and provide support for those able to do so on a large scale.

Monarch butterflies have always been provocative!  With many of their overwintering grounds in eucalyptus trees and located in the high end real estate of the California coast, there have always been conflicts about the right thing to do for this species.

Now that the population throughout North America has declined so precipitously, it is time for a wake up call.  Sure will make for good and thoughtful discussion, hopefully some serious changes too that could hopefully lead to more attention and respect for other butterflies, their relationship to plants.

We also hope to have a wider discussion this fall:  2015 marks 200 years since western science observed monarchs in California, and this was on what we now call the Presidio!

Showy milkweed is native to California. Photo: Philip Bouchard/Flickr

Showy milkweed is native to California. Photo: Philip Bouchard/Flickr

Western monarchs overwintering in Arroyo Grande, California.

Western monarchs overwintering in Arroyo Grande, California.

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PaulCherubini on March 3rd, 2015 at 2:30 pm

Non-native Australian eucalyptus trees support 90% of the overwintering monarchs in California, but native plant agenda purshing organizations like the Xerces Society are trying to get rid of the eucalyptus! Just like they are trying to get rid of the non-native monarch magnet nectar plants (Pride of Madiera, DaisyTree, Buddleia bushes, Bottlebrush, English Ivy). So it is not surprising the Xerces Society is trying to get us to believe non-native tropical milkweeds should not be planted and are a threat to the monarch migration. Xerces knows darn well that non-native tropical milkweeds support 100% of the migratory monarchs in Australia/New Zealand/Spain/Portugal so it’s absurd to think they are a threat to the migration.

Rachael Brown on March 4th, 2015 at 6:12 am

Planting tropical milkweed that doesn’t die back in winter actually prevents monarchs from completing their migration which in turn makes the monarchs more susceptible to a parasite that is killing them. And like Liam says in the article putting milkweed in a migration area where they really need migration food is not helping either.

Scott Simono on March 4th, 2015 at 8:15 am

@PaulCherubini: Eucalyptus trees act as roosts for the overwintering Monarchs, and in California only, not in Mexico. They don’t feed on the trees and they would roost in native trees had we not chopped most of them down. Tropical milkweeds attract Monarchs to areas they cant survive as a population and it triggers developmental processes at times/seasons that ultimately lead to the demise of the butterfly. That you “save the Eucalyptus” people will stoop to any form of hysterical misinformation and lying is getting insanely tiresome. (By the way, Monarchs are NOT native to Australia/New Zealand/Spain/Portugal). People like you are disturbing.

Ward Johnson on March 4th, 2015 at 12:10 pm

The right way to solve the Monarch decline is to plant Milkweed.

At SaveOurMonarchs.org anyone can get free milkweed seed packets. Just go toh SaveOurMonarchs.org/store/c4/Get_Seeds.html

They usually ship the same day they are ordered.

Ward Johnson

PaulCherubini on March 11th, 2015 at 9:28 pm

Scott Simono, you are correct monarchs are not native to Australia/New Zealand/Spain/Portugal. Nor are evergreen tropical milkweeds. But those introduced evergreen tropical milkweeds are the only milkweeds available in those countries and they have sustained their monarch migrations for 150 years. That’s why it’s absurd for anyone to think planting non-native tropical milkweeds in California could stop California monarchs from migrating. The City of Pacific Grove, California has the most famous overwintering habitat in the State and does not follow the anti-native plant advice of the Xerces Society/Liam Obrien/Mia Monroe. So they plant eucalyptus trees for the monarchs and several non-native nectar plants such as DaisyTree (Montanoa grandiflora, buddleia bushes, Pride of Madiera, Bottlebrush and non-native flowering fruit trees. Similarly, at the Ardenwood Historic Farm overwintering site in Fremont, Calif. the local park district has planted various non-native nectar plants a large amount of a non-native evergreen milkweed from South Africa.

Crystal Sage on March 13th, 2015 at 11:21 am

Help save the Monarch. vote for our girl scout troop to win $500 in this contest so that we can purchase milkweed seeds and distribute them throughout our community.

Ard Beard on March 21st, 2015 at 12:04 pm

So let’s plant more native Milkweed here in California.
I’m doing my small part. Having developed a nice patch of A. eriocarpa here in Mendocino county I can offer seed to anyone interested.
They are easy to germinate, perennial, water wise plants.
And Monarch magnets for sure.
Seeds available on ebay search for seedinsoil or eriocarpa.
Ardatmaddotscientistdotcom is for mail.

will thrift on April 20th, 2015 at 1:26 pm

Wow, to an “outsider” like myself, this dialogue looks like Wash DC politicians, with two extremist points of view.

I just hope that you all grow up soon and start behaving/talking like adults.

Mary McAllister on May 25th, 2015 at 6:19 am

Here’s a middle-ground viewpoint from Professor Art Shapiro. Professor Shapiro (UC Davis) is an expert about California butterflies. He was asked about planting non-native milkweed when we spoke recently at Annie’s Annuals in Richmond. He said that you planted tropical milkweed, you should cut it back in winter so that it would make new growth in spring. That way the plant doesn’t accumulate the parasites that are harmful to butterflies. It’s also good for the plant which gets weedy-looking if it’s not cut back to renew its growth in the spring.

Yuba Sutter MG on July 5th, 2015 at 7:28 pm

The Milkweed seeds offered by Save Our Monarchs are an Eastern milkweed A.carnata which is not found in the West. Native species from local sources are a better bet.

Yuba Sutter MG on August 9th, 2015 at 8:20 am

I can offer gratis Narrow Leaf milkweed seeds we have just collected in Butte Co. to anyone interested in planting some – Just send a self addressed stamped envelope and we can send 20 seeds right back to you. Contact goodvibrationssecty@gmail.com.

Fletch on October 17th, 2015 at 9:43 am

With not one mention of the impact of pesticides, how can this website be taken seriously at all? Boycott quasi science and quasi scientific websites such as this one.

Yuba Sutter MG on October 19th, 2015 at 10:21 am

It is now October and almost time to plant milkweed seeds for Spring germination. We have lots of Narrow Leaf, Showy and Kotolo milkweed seeds collected in Butte and Plumas Counties. Available free of charge to any interested parties in Northern California. Contact: goodvibrationssecty@gmail.com

James stoval on May 21st, 2016 at 9:34 pm

Liam…not true.grew up in sf bay area.. used to be lots of fields . Full OF MILKWEED….WE..AS KIDS HARVESTED CATAPELLERS…….THE PLANT GROWS ABOUT THREE FEET TALL ; and a seed ball resembling a giant dandy lion…and disputses it seeds in the exact same manner… ps resemtly discoverer a patch of about ,100 plants and have started seeds..can send picture

Lech Naumovich on October 10th, 2016 at 2:56 pm

Upon review of herbarium specimens from CCH/Smash database, there are in fact no records of Asclepias in SF county/City. Liam O’Brien’s claim is supported by this lack of collection material. This is not to say that milkweed was completely absent, but rather that it was likely in low numbers and thus not being an important resource for monarchs in this area. Thanks for the great article Bay Nature – this is an important topic to discuss.
Notably, a few organizations/collectors offer milkweed seed from hundreds of miles away. I would highly discourage that other than for garden/ornamental use, since local genetic material is usually preferable and well adapted to local climate conditions.

Mia Monroe on October 14th, 2016 at 9:19 pm

Sure sign of season’s change to autumn: the arrival of monarch butterflies in the coastal CA region! Already reports are coming in of small clusters in coastal Marin, Santa Cruz and Alameda counties plus late season reproduction, too to thrill many of us with the full cycle of metamorphosis before the long and indispensable overwintering period…thx for reviewing this message string about what we can each due depending on where we are!

Plus, a historical footnote:
The RURIK sailed into SFBay (and anchoring, going ashore at the Presidio of SF) in early October 1816…a Russian expedition enroute to seek the elusive northwest passage.

The ship Rurik carried only twenty-seven people, including Captain Kotzebue, scientist Adelbert von Chamisso, and artist Choris as well as the ship’s surgeon, Johan von Eschscholtz.

These curious people provided the earliest documentation, descriptions and specimens to the rest of the world of the California poppy, chert, the monarch butterfly as well as the peoples they encountered. They evidently got along well and named the new sights after each other. The type specimens are in European and Russian museums but once were on display here.

Accounts of their journeys are fascinating, Kotzubue (and Eschscholtz) returned in 1824 and made an extensive foray into Marin.


Yuba Sutter MG on October 26th, 2016 at 8:36 am

We have a very large quantity of 2016 Showy milkweed seeds to give away, please contact goodvibrationssecty@gmail.com. Thank you.

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