Because of their fruiting, reminiscent of birds, the common milkweed is sometimes confused with the bird of paradise (Strelitzia reginae).
However, those of the common milkweed do not only form long beaked heads but entire bird bodies – a truly remarkable view, especially appealing to exotic plant fans.
The common milkweed, botanically named Asclepias syriaca, belongs to the milkweed subfamily within the dogbane family. It also has epithets such as silkweed or butterfly flower.
Despite its exotic-looking name and appearance – especially that of the fruits – the common milkweed is not really exotic. In any case, it does not come from areas such as the tropics.
Originally, the perennial comes from the eastern part of North America and the Pannonian Floral Province. That is an area that includes the Hungarian Plain, as well as parts of Serbia, Romania, Slovakia, Austria, and Moravia.
The common milkweed is thus adapted to a relatively diverse repertoire of habitats. It thrives in its native areas primarily in dry, mild areas, but is largely hardy. Thus, outdoor cultivation is quite possible.
Origin in keywords:
- Common milkweed comes from North America and the Pannonian Floral Province (Hungary to Romania, Serbia, Slovakia, Austria, and Moravia).
- Thrives mostly in dry, mild locations.
- It is largely hardy.
The common milkweed grows as a perennial and reaches heights of about 3 to 6 ft (1 to 2 m). The erect stem is light green in color and slightly hairy. Usually, the plant shows little or no branching.
It holds on to the soil with a taproot and forms rhizomes – and quite spreading ones at that. They behave as aggressively as those of bamboo and must be kept in check with a root barrier if uncontrolled spreading is to be prevented.
Even tearing out the root for removal purposes is usually useless – from the smallest root remnants, the common milkweed can sprout again undaunted.
In addition to this intensive root dispersal, the common milkweed also reproduces very strongly via seeds when they fall out of the ripe bellows fruit.
Because of its strong dispersal mechanisms, common milkweed was classified as an alien invasive plant species by the European Commission in 2017.
Its population should thereby be pushed back to protect the European native flora. That’s why you won’t find any common milkweed or seeds for sale in plant shops in Europe anymore.
Therefore, it goes without saying that a rhizome barrier and the timely prevention of self-seeding should be observed during cultivation.
Growth characteristics at a glance:
- Common milkweed grows as a perennial.
- It can reach about 3-6 ft (1-2 m) in height.
- It has an upright, light green, slightly hairy, and hardly branched stem.
- The common milkweed has taproots with aggressive rhizome formation.
- In addition, it also has strong self-seeding.
- Therefore, it is officially classified as an alien invasive species in Europe and no longer commercially available there.
The leaves are short-stalked and have an elliptical to ovoid outline with a blunt to a slightly pointed tip. They are attached cross-opposite to the stem, which is usually barely branched.
In size, the leaves reach about 6 to 12 inches (15 to 30 cm) in length and 2 to 5 inches (5 to 12 cm) in width. The leaf margins are completely marginal. Like the stem, the undersides of the leaves are slightly hairy.
In July and August, the common milkweed produces many small flowers that stand together on the short stems in delicate, spherical, very pretty umbels.
The single florets have a scarlet-pink base and turn to whitish and greenish pink at the corollas. Overall, they have a length of about 3 to 5 mm. The flowers emit a strong, pleasant honey-like fragrance.
Flower characteristics in brief:
- Large, spherical umbel inflorescences of numerous, small flowers.
- Appear in July and August.
- Color scarlet pink, changing to whitish.
- Strongly fragrant.
The fruit that emerges from the flowers is actually the highlight of the common milkweed. In fact, the elongated bellows fruits, bent like horns at the bottom and greenish to brownish in color, certainly look like small budgies standing on their heads.
For decorative purposes, they are cut off and sold in stores with black dots as eyes, and marketed as small parrot figurines.
The fruits are about 3 to 6 inches (8 to 15 cm) long and have a soft-thorny texture. Inside they form numerous seeds, which are provided with silky thread scoops. These are used for onward transport when the ripe fruit bursts open, allowing for widespread dispersal.
The silk hairs are also used in some areas as padding material, for example for pillow stuffing.
Fruit in keywords:
- From flower form elongated, below horn-like bent bellows fruits.
- Length about 3-6 inches (8 – 15 cm).
- Reminiscent of small budgies.
- Can be arranged for decorative purposes as figures.
- Rich seed formation, seeds with silky plumage.
- Their silky hairs are sometimes used as cushioning material.
What Location is Suitable for Common Milkweed?
The common milkweed generally likes it rather sunny and dry. It will thrive in partial shade as well, but you will have to expect less abundant and not quite as fragrant flowers.
The tall, hardly branched growth also requires a rather wind-protected spot.
If you want to keep the common milkweed in a container, the same conditions apply, but in winter you should not bring it into a warm room, but overwinter it in a cool place.
What Kind of Soil Does Common Milkweed Need?
As a substrate, the common milkweed needs a loose, relatively humic, and, above all, permeable soil and a slightly acidic soil environment.
It is important to incorporate a good drainage layer with some sand and/or clay granules, both when planting outdoors and in containers, especially in heavier, firm soils. Common milkweed does not tolerate waterlogging at all.
Very important when planting outdoors: do not forget an effective rhizome barrier!
Watering common milkweed
You should water the common milkweed regularly, but moderately. Generally, dryness is better than waterlogging.
Fertilizing Common Milkweed Properly
You can take good care of the common milkweed with an annual organic fertilizer application later in the spring. When planting, you should already apply some leaf compost and/or horn shavings to the soil. In the following spring, you can also fertilize it with compost or pelleted cattle manure.
You should supply a specimen kept in a container with a universal liquid fertilizer for flowering or container plants during the main vegetation phase over spring and summer. To do this, add some to the watering every two weeks.
Is Common Milkweed Winter Hardy?
As mentioned above, the common milkweed is conditionally hardy. It can tolerate light frost so you can cultivate it outdoors all year round.
However, both in the tub and in the outdoor culture you should take some protective measures when it comes to longer, severe cold periods.
For an outdoor specimen, it is best to mulch the planting ground and/or cover it with fir branches or garden fleece. Additionally, it is recommended to wrap the plant with burlap.
If you keep a specimen in a container you can either leave it outside and wrap the container as well as the plant with burlap, jute, or similar.
Or you can simply place the container in a frost-protected winter quarter. This should preferably be relatively bright and cool because of the vegetation dormancy, more than around 50 °F (10 °C) should not prevail there.
- Common milkweed is reasonably hardy.
- Protect both outdoors, as well as specimens cultivated in the tub against stronger cold periods with fir branches, garden fleece, burlap, etc.
- If necessary, overwinter vulture specimens indoors, but not too warm with a maximum of 50 °F (10 °C).
Propagating Common Milkweed
As mentioned, the common milkweed is quite invasive and is now quite officially even a plant to be decimated throughout the EU. If you live in the EU, you need to prevent it from the invasive spread.
To this end, you should use an effective rhizome barrier for outdoor cultivation and cut off the fruits in good time before they burst open and spread their many seeds far and wide.
Of course, those who want to multiply their private stock can do so. As a method of propagation, you can divide the plant, use cuttings or take seeds.
The rhizome root system of the common milkweed is very eager to sprout, so to get a new specimen, you can simply cut some off.
Simply pry off a piece of root with a spade and place it either in a planting hole outdoors – again, with a rhizome barrier, of course – or in a container of potting soil. Sprouting will probably not be long in coming.
You can also cut cuttings and grow them in planters with a growing medium in a bright, warm place indoors. Spring is the best time to do this. Moisture can be kept more evenly under plastic wrap.
Since the fruits of the common milkweed form very many and easily manageable seeds, seed cultivation is particularly suitable for propagation.
For harvesting, meticulously match the time when the fruit is ripe, but not yet burst open. Otherwise, the seeds will be scattered to the winds by their silk hairs.
You can plant the seeds indoors all year round. Cold treatment increases the chance of germination. To do this, put the seeds in the refrigerator for about a week.
Then put them in pots with growing soil and cover them with it only lightly. The place should be bright, but not too warm, about 59 to 64 °F (15 to 18 °C).
Is Common Milkweed Poisonous?
Like all spurge plants, the common milkweed contains a mildly toxic milky sap, but it mainly causes skin irritation.
If small children or small pets such as guinea pigs, rabbits, or cats populate your home, you may want to refrain from purchasing it or place the plant out of their reach. In fact, ingestion may result in mild symptoms of poisoning.