Common milkweed plants are tall (3 feet), thin, summer-bloomers. The flower cluster forms a globe atop the plant's rigid stem. The flowers come in various shades of pink, and they are fragrant flowers. Leaves are broad-oblong and light green. Seed pods that resemble small cucumbers succeed the flowers. The pods, in turn, burst open in late summer to early fall, exposing their seeds. The seeds are attached to white silky hairs, meaning the slightest wind will distribute them.
Planting Zones for Milkweed Plants
Milkweed plants grow like wildflowers in fields and along roadsides in Eastern North America. The common type typically grows in zones 3-9.
Sun and Soil Requirements
Common milkweed plants grow best in full sun and well-drained soil, but, as tough as they are, they tend to tolerate clay soil, as well. Like many types of wildflowers, Asclepias syriaca is a drought-resistant plant.
Uses for Milkweed Plants in the Landscape
Famed as a plant that attracts butterflies, this wildflower is a must-have for the butterfly garden. It is the host for monarch butterfly caterpillars. Monarch butterflies deposit their eggs on milkweed plants; once the caterpillars emerge, they eat the leaves.
Others grow it specifically for wildflower gardens. Another use for it involves the seed pods: they can be dried and used in crafts.
There's no need to fertilize milkweed plants, as they tolerate poor soils. Your biggest maintenance challenge with them will probably be in containing them. Asclepias syriaca spreads both via seeds and rhizomes, forming colonies.
At the very least, you may wish to remove the seed pods before they open. Otherwise, they will spread to distant corners of your yard (and beyond), thanks to the silky appendages that allow the seeds to waft on the slightest breeze. They are rather like the seeds of dandelions in this regard.
Caveats in Growing Milkweed Plants
While some parts of Asclepias syriaca served culinary and medicinal purposes for the native population, this wildflower's status as a poisonous plant warrants mention since its leaves are toxic. Never ingest wild foods until you have first consulted with experts (I am not an expert in this area).
Unless children or pets are in your yard, a more serious drawback to growing it may be its proclivity to spread aggressively (see above in the "Care" section).
Other Types of Milkweed Plants
Many find butterfly weed (Asclepias tuberosa), with its bright orange flowers, a more attractive type of milkweed than the common milkweed. Another type of milkweed is swamp milkweed (Asclepias incarnata).
Fun Facts About Milkweed Plants
- The genus name, Asclepias derives from the name of the Greek god of medicine, Asclepius; it refers to its medicinal uses. The specific epithet, syriaca, may, however, be a misnomer, according to Gaertner and others: from most of what I've read on the subject, Asclepias syriaca appears to be indigenous to North America, not to Syria.
- Upon any damage to the stem or leaves, a white, milk-like substance oozes out, which gives the weed its common name.
- As mentioned above, the leaves are poisonous, and the monarch butterfly caterpillars treat these leaves as a food source. While they, themselves do not die from eating them, the toxins make the caterpillars poisonous to predators -- a nice trick!
The Pros and Cons of Growing Common Milkweed
Its status as a must-have for the butterfly garden is certainly one of the pros for growing common milkweed. Or should we say "allowing it to grow," since the ease with which its seeds are dispersed means that this weed tends to volunteer its services. That means it's free, which is also a pro.
Common milkweed is the host for monarch butterfly caterpillars. Monarch butterflies deposit their eggs on the plant; once the caterpillars emerge, they eat the foliage. Most people are more interested in butterflies than in caterpillars, per se, but these caterpillars are rather attractive, in their own right.
Another selling point for common milkweed is its fragrant flowers. But given a choice between this plant and its relative, butterfly weed, many would choose to go with the latter if the decision were to be based solely on floral color. And unless you have room for a sprawling wildflower garden, a serious drawback in growing common milkweed is its tendency to spread.