Why You Should Be Planting Milkweed this Year In Pleasantville

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Purple Milkweed (Asclepias purpurascens)
Purple Milkweed (Asclepias purpurascens) Photo Credit: Contributed by Kim Eierman

WESTCHESTER COUNTY, N.Y. -- Our youngest generation may be the last to ever see a beautiful Monarch butterfly.  Since the 1990s the Monarch population has dropped by more than 90 percent from an estimated one billion Monarchs to only 33 million today.   

There are a number of reasons why the Monarch population is crashing – deforestation of their overwintering sites in Mexico and California, radical changes in farming practices, widespread pesticide use, and the disappearance of milkweeds.

Butterfly caterpillars have a different diet than their adult counterparts.  Most caterpillars eat plant parts, usually leaves.  Monarch caterpillars have evolved to eat only the leaves of milkweeds (Asclepias species) which are their “larval host plants.”

While we often plant nectar-producing plants in our landscapes to feed adult butterflies, we rarely plant the larval host plants that their caterpillars must have. This absence of host plants in our landscapes, in combination with our frequent use of pesticides, has contributed to reduce the populations of many butterfly species – including the highly threatened Monarch.

This fall, you can help save the Monarch butterfly in your own landscape in two ways:  1) plant regionally native milkweeds and 2) keep your landscape pesticide-free.   

In spite of their unfortunate common name, milkweeds are beautiful and wonderful additions to every yard.  Not only do milkweeds feed Monarch caterpillars with their leaves, they support countless pollinators and other beneficial insects with their nectar.

Here are some native milkweeds to consider planting this fall:

Swamp Milkweed (Asclepias incarnata)

Full to part sun
2 – 4 feet high
Pink blooms in summer

Butterflyweed (Asclepias tuberosa)

Full sun;welll drained soil
1-3  feet high
Orange blooms in summer

Purple Milkweed (Asclepias purpurascens)

Full to part sun; dry to moist soil
2 – 4 feet high
Rose pink blooms in summer

Whorled Milkweed (Asclepias verticillata)

Full sun to part sun; dry to moist soil
1 – 2 feet high
White, light green blooms in summer

Tall Milkweed (Asclepias exaltata)
Part shade to part sun; average to moist soil  
2 – 5 feet high
White, light green blooms in late spring to early summer

White Milkweed (Asclepias variegata)

Full to part sun; average to moist soil
1-3 feet high
White blooms in early summer

Common Milkweed (Asclepias syriaca)

Full to part sun; average to dry soil
2-6 feet high
Pink blooms in summer

Common Milkweed is a critical plant for Monarchs but has a spreading root system and should be sited accordingly.  It is a wonderful choice for natural areas and a terrific replacement for tough invasive plants in sunny spots.

For more in-depth information on milkweeds: http://www.ecobeneficial.com/2014/07/closer-look-monarchs-milkweeds-latest-information-xerces/

Look for milkweeds at your local nursery and also join me at the Native Plant Appreciation Weekend at Rosedale Nurseries in Hawthorne on Sept. 6-7.   Volunteers from The Native Plant Center will be on hand to help you shop for lots of great native plants – including milkweeds!

Kim Eierman, a resident of Bronxville, is an environmental horticulturist and Founder of EcoBeneficial!  When she is not speaking, writing, or consulting about ecological landscapes, she teaches at the New York Botanical Garden, Brooklyn Botanic Garden, The Native Plant Center and Rutgers Home Gardeners School.


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Comments (7)

Great article! Planting milkweed and avoiding pesticides are great steps to help monarch butterflies. I planted milkweed last spring and more this spring. I was rewarded by one monarch visiting this week to lay eggs!

Please disregard Paul Cherubini's comment. He shows up on every monarch butterfly article I've seen read in the last year with similarly outlandish claims.

Past 10 years I have seen fewer & fewer Monarchs around Westchester & in particular my backyard. Prior to my planting milkweed over 3 years ago, I saw no Monarchs in my backyard for a few seasons. I planted Milkweed after reading up on the plight of the Monarch. Much of my info came from the group Paul mentioned. Last year I had 2 monarchs visiting, This year I had 3. My patch is now about 10x30, (was originally 5x7 when I started it). The Cm. milkweed has spread a bit, but I am happy with the results, it all stays & I will start to replant next years new shoots. We need more awareness,and just as important, info on what we can do to help. Kim's piece provides both, great work, It's a keeper for someone looking to get started! Very little effort required!

Common Milkweed (Asclepia syriaca) is an important plant for Monarchs and many other beneficial insects as well. It is known to produce nectar not only during the day, but also at night, supporting many nocturnal moths, some of which are in real decline too, like the Luna Moth.

As you point out, Common Milkweed is rhizomatous (a type of spreading root system) and will create dense stands. It is a wonderful plant for naturalized gardens and other natural areas, as well as an excellent choice for sunny, well-drained areas which have been taken over by non-native invasive plants. If you have Common Milkweed present in your landscape you are fortunate - it has been completely eradicated from most of our suburban landscapes.

For areas of your landscape where a rhizomatous plant is not wanted, there are many milkweed alternatives, some of which are cited in my article. Choose species that are native to your area and fit the conditions that you have. Plant diversity is critically important to a healthy ecosystem - so try to plant more than one species of milkweed which has evolved in your area - all of these plants are important within your ecosystem.

Paul doesn't live here so he hasn't seen the drop in numbers that we have the past two years. I have seen a total on one so far this year. I have a few fields that are managed for wildlife and have plenty of milkweed. As the author states agricultural practices have helped the monarch population, but these man-made habitats have slowly been disappearing as the farms revert to forest. However, the recent perciptous decline is not due to just this, Paul.
Paul has one valid point in that you don't need to buy milkweed seeds or plants, etc. Common milkweed is one of the few deer proof plants in our area and readily spreads itself with its rhizomes and establishes new patches with it's wind dispersed seeds. What would really help in our area is better field management, and the creation of more "fields" including our own small and big yards.
I think Paul would agree that it is all about education, as usual.

Mr. Cherubini - please refer to the countless studies which invalidate your comments about the state of the Monarch population. With regard to those hard-working, underpaid folks at the non-profits who are trying to save Monarchs and other threatened species - I say "thank you" to all of you. You deserve our admiration and our support.

Paul - can you please provide links to the peer reviewed scientific studies that show that the monarch butterfly is not going extinct. Thanks in advance.

Far from going extinct, eastern USA monarch butterflies are actually thriving by the tens to hundreds of millions. Their numbers were artificially inflated during the period 1850-2000 by agricultural practices that increased the abundance of milkweed plants in crop fields. All these monarch extinction scare articles are really marketing tools in disguise designed by the dot orgs to motivate the public to place orders for hundreds of thousands of dollars worth of milkweed plants, milkweed seeds, milkweed waystation registry applications and waystation signs. Half the profits generated are used for payroll. So the employees of these dot orgs are laughing all the way to the bank.