An Introduction To Common Milkweed

Common Milkweed is a perennial wildflower native to North America. It is one of the plants that Monarch Butterflies (the Asclepias genus) will lay their eggs on, and as such is critical to their survival. Scientifically known as Asclepias syrica, it grows 3-5′ tall in full sun and well-draining soil. In addition to being important for Monarch caterpillars, it’s flowers feed numerous species of bee and other butterflies with nectar and pollen^[1][2].

Now, while the ‘common’ name may seem to imply it isn’t special, I assure you that is not the case. This plant is critical for the survival of Monarch Butterflies, probably more so than most other Milkweed species (in North & East) due to how it is so prolific. But there have been nearly 100 different insect species feeding on or utilizing Common Milkweed^[3].

In this article:

• Origins of it’s name
• Pros and cons in the landscape
• Identification / Characteristics
• Growing conditions
  • How to grow from seed
• Wildlife associations / uses
• Where to buy Common Milkweed
• Landscaping with Common Milkweed
• Final thoughts

The story behind Common Milkweed’s name

Why is it called Milkweed?

The ‘milkweed’ part of the name comes from the characteristic it has, in which you tear a leaf you will see a milky white sap ooze from the open wound.

Where does that ‘common’ name come from?

Now the common name of this plant contains the word ‘common’, and based on this fact you could probably guess that it has an extensive range….and you would be correct. It’s native range covers nearly half of the country, thus if you ever ventured East of the Rockies you’ve probably encountered it (knowingly or unknowingly). But the flowers are very attractive in Summer when the flowerhead they make bloom pink-white-purple flowers, and it’s seed pods in fall/winter are beautiful too when the seeds are slowly escaping.

Native Range

But it is more prolific than just it’s native range….it’s also so ‘common’ (I couldn’t resist) because it can spread prolifically. And it does this by sending out underground stems that travel horizontally beneath the surface, and send up new shoots that create new plants. So if you see a single mature plant, there is likely an extensive root system that is seeking out new opportunities to spread and claim territory. These new sprouts are quite easy to transplant and establish if done correctly.

And when it can successfully make a new plant in this method, it isn’t just some small quaint little flower. Oh no – if enough sun and moisture are around it can easily grow to 4-5′ tall. This height will allow it to compete with just about anything.

Reference Table

Scientific Name	Asclepias syriaca
Common Name(s)	Common Milkweed, Milkweed
Native Range, USDA Zone	Eastern North America, USDA Hardiness Zone 3-9
Bloom Time	June to August
Bloom Duration, Color	4-6 weeks, white/pink/purple
Height	2-6′ tall
Spacing / Spread	2-3′
Light Requirements	Full sun
Soil Types	Sandy loam to clay
Moisture	Slightly moist to slightly dry
Fauna Associations / Larval Hosts	Numerous pollinators / hosts Monarch Butterflies

Pros and cons

Pros

Helping the Monarch Butterfly survive

As already stated earlier in the article, Common Milkweed is a larval host for the Monarch Butterfly Caterpillar. What that means is that Monarch Butterflies will lay their eggs on it, as the caterpillars will only feed on leaves of milkweed plants

Feeding numerous pollinators

There have been nearly 100 different species of insect documented as visiting for nectar, pollen, or eating the leaves of Common Milkweed. It’s popularity as a food source for so many species is a testament to it’s importance to our ecosystems.

Deer and rabbit resistant

The foliage and stems of Common Milkweed contain a milky white sap that is toxic and bitter tasting, which leads deer and rabbits to generally avoid browsing this plant. They don’t like the taste!

Beautiful

The flowers of this plant are beautiful and incredibly interesting when examined up close. But a patch of this plant blooming in unison is absolutely exquisite.

Cons

Aggressive

Common Milkweed is one of the more aggressive of the Milkweed species. It can be challenging to garden with this plant and keep it looking nice, as it will be sending out runners everywhere. These runners will send up new shoots all over the place (even your lawn).

Identification and Characteristics

Stalk

Typically growing 3-5′ tall, it is possible for this flower to top out around six feet in height under perfect conditions and minimal competition. but the stalk of this plant is round and pale green.

Leaf

Leaves of common milkweed are opposite and can get quite large, upwards of 7-8″ by roughly half as wide. They are oblong in shape with a prominent central vein, and have smooth margins. The upper surface is green and smooth while the underside will have small white hairs densely covering it^[2].

If you tear a leaf or rip one off, a white milky sap will ooze from the wound. If you happen to touch it, beware as it is toxic and can be particularly damaging to your eyes.

Flower

At the upper leaf junctures and at the top of the plant there will be clusters of flowers (umbels) that range from two to four inches diameter. The individual flowers have long pale-green stems (pedicels) and are in what I call the the ‘milkweed style’ with it’s oh-so-unique structure. There will be five reflexed petals (petals that are bent back, nearly perpendicular to the axis of the flower) with five raised hoods underneath. The petals are generally purple or pink while the hoods are more pale or white^[2]. This flower structure is very unique when you encounter it, and is shared by just about every species of Milkweed as far as I’m aware.

How to save seed from Common Milkweed

After blooming, over the course of six to eight weeks a seed pod will develop containing several hundred seeds. The pod will narrow to a tip with a fatter, blunt base, and the outside will be textured/worted. Once these seeds are ready, the pod will begin to dry out. As it dries, the shrinkage will open a tear at a seam in the pod and the seeds will slowly start to release.

Also, if collecting from the wild, know that you really only need a single pod to have hundreds of seeds. There is no need to take all pods from all plants^[5]!

So, to save the seed, you have several options.

• First is to just watch/pay attention to when the seed pod starts to open, and when it is just beginning, you can harvest pods. Then, to get the seed cleanly you can roll the pod between your hands with firm pressure. This will allow the feathers bind to themselves, and when the pod is opened it will be one mass of seeds/feathers rather than individuals that fly everywhere.
• Second option is to place a mesh drawstring bag over a few pods before they fully ripen, then just wait. Once the seeds are ready, they won’t be able to escape and float away as they are contained in the mesh bag.
• A third option is to place a small rubber band or twist-tie on a pod or two, and leave the others alone. Then just check periodically to see when the pods are ripe, and harvest them at that time.
• Finally, if you are out for a walk or hike and you see seed being released from some random plants, just take a pod or two in the process of releasing seed.

The seed should be left to dry in a garage or cool dark place for a few days, and then can be stored in an envelope for a couple years, again out of direct sunlight and at room temperature.

Root

The root system of Common Milkweed is fibrous with rhizomes. These rhizomes spread horizontally, and will go down deeper (to a certain depth) when a barrier is encountered, in an attempt to get around it.

Growing Conditions

When it comes to growing conditions and soil textures….don’t over think it! Common Milkweed can grow in a huge variety of environments. The only two factors to avoid are extreme drought, too much or too-little drainage, or a lack of sunlight. But Common Milkweed will prefer full sun (but can grow in part-sun) and sandy loam to clay soil with organic matter. It grows best in slightly moist conditions. And as previously stated, it is a tough plant though and can tolerate a wide variety of soil conditions.

How to Grow Common Milkweed from Seed

Seeds of Common Milkweed have a dormancy mechanism to prevent germination in inopportune times. So, if you just plant a seed, you may not have it germinate unless you’ve satisfied the dormancy requirements. And these requirements are a cold-moist stratification period of roughly 2-4 weeks^[6].

You can do the cold-moist stratification by using a paper-towel in the fridge, winter sowing, or even just planting your seeds in very early Spring when nighttime temperatures still dip close to freezing.

But to plant Common Milkweed seeds, fill a suitable container with moist potting soil. Sprinkle your seeds on top of the soil and gently press them in. Then, give them a dusting of potting soil, so that the seeds are a mix of just barely covered or partially covered.

Related ==> If you want more details and pictures, see our guide to germinating all Milkweed seeds.

Place this container in a location that receives morning sun and afternoon shade. Once daytime temperatures are consistently above 60F, you should get germination within two weeks.

Establishing Common Milkweed

When there are several sets of true leaves on the plant, you can thin or separate seedlings, transfer to a larger container, or transplant to a final location. While this plant is deer and rabbit resistant, you should protect the young seedlings with a cage or liquid fence for the first season.

This brings me to my next point, as this is a long-lived perennial, you should not expect the plant to bloom it’s first year. During it’s first growing season in the ground, it will focus on developing roots. However, by the second year if it is in it’s preferred growing conditions it should bloom.

Wildlife associations

Pollinators

Common Milkweed will feed a variety of insects including Long-tongued bees, short-tongued bees, wasps, pollinating flies, butterflies, and hummingbirds. Charles Robertson in his amazing 1929 survey documented ninety-nine different species visiting this plant^[3].

And as noted, the Monarch Butterfly caterpillars are hosted on this plant. But there are other species including Tussock Moths and Milkweed Beetles.

Tussock Moths or Tiger Moths

If you happen to walk out to your milkweed patch you may be greeted by dozens to hundreds of fuzzy muppet looking caterpillars. These are Tussock Moth caterpillars and they are a bit creepy. But they should not be removed, as these are native to North America, and they like to eat Milkweed for the same reasons Monarch Butterflies do, the poison provides them some protection from birds^[6][7].

They are part of the food chain, and while unsightly, they will eventually be food for other insects and birds when they become moths. So, we need to keep them. The good news is that having some of your plants become infested, or ‘Tussocked’ as we like to say is not an every year occurrence. And when it happens, just snap a few pictures of these interesting little creatures and know that you are doing the right thing by leaving them be.

Milkweed beetles

If you begin to notice small red beetles near the seed pods, well, you’ve got Milkweed Beetles. And at this stage of their life they enjoy eating the developing Milkweed seeds^[9]. If you are trying to save some seed, then I suggest you purchase some mesh drawstring bags, and place them over some still-developing pods that haven’t been attacked. This should protect it from being attacked by the beetles, so they can have some pods and you can keep a couple unmolested so that the seed can develop and mature.

Deer and Rabbits

Deer and rabbits will avoid common milkweed as the bitter tasting, slightly toxic white sap makes them not want to eat it! Young plants, just emerging or new seedlings will not have as much protection though and may be eaten.

Disease

Common Milkweed is generally disease free. If the plant is being heavily fed on by insects though it may look unsightly, but this is natural and normal.

Where you can buy Common Milkweed

Common Milkweed is not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.

Where to buy seeds

We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)

Landscaping with Common Milkweed

Common Milkweed is an aggressive spreader, and you need to account for this when using it in a home landscape. It can be done, but not without some effort.

Related ==> There are other ways to support Monarchs besides planting common Milkweed. See our list of non-spreading Milkweeds, or other plants to support Monarchs that aren’t Milkweed (these support their migration by giving them late-season nectar).

One option is to only plant Common Milkweed in a flower bed that is isolated and surrounded by a large amount of lawn – perhaps twenty feet in all directions. This will allow you to continually mow new sprouts while the center bed can be planted with other natives that are aggressive enough to compete with Common Milkweed.

A second option is to only use it in border areas with a forest or some other natural barrier. Again, this should be a mixture of grasses and other natives that can hold-their own with Common Milkweed, ideally selecting them to provide a succession of blooms from Spring to Fall.

Finally, you could try my patented method of stopping aggressive plants from spreading (it has contained Obedient Plant and BeeBalm for years).

Companion Plants

Below is a listing of companion plants that can grow near Common Milkweed that will not be crowded out, and can be a nice compliment to it.

Spring Blooms	Summer Blooms	Fall Blooms	Grasses
Bee Balm	Anise Hyssop	Common Boneset	Big Bluestem
False Sunflower	Blazing Star	Liatris aspera	Little Bluestem
Foxglove Beardtongue	Ironweed	Maximilian Sunflower	Virginia Wild Rye
Golden Alexander	Joe Pye Weed	New England Aster	Canada Wild Rye
Pale Purple Coneflower	Wild Bergamot	White Snakeroot	Indian Grass

Final Thoughts

Common Milkweed is an amazingly important plant to our ecosystem as well as the Monarch Butterfly. Feeding such a variety of pollinators truly speaks to it’s importance. And although it is quite beautiful, it can be a garden nuisance if one is trying to maintain a manicured mulched flower bed. That being said, there are ways to effectively utilize and contain it.

Find more native plants here