Milkweed--Thug or Beneficial?

Marty Young
Adams County Master Gardener

March 21, the first day of spring. What better time to think about spring and what new plants to choose for your garden. If you have a plan for your garden, I hope it includes plants for pollinators. This can encompass a wide range of plants and insects so let’s narrow it down to milkweed. Don’t stop reading yet—there are many varieties of milkweed and they are all good in your garden.

Asclepias is the Latin name for all the milkweed varieties even the one farmers dislike. This variety, Asclepias syriaca or common milkweed, is considered invasive. 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. Milkweed seeds are spread by the wind, which catches the fluffy part and carries the seed for long distances.

Common milkweed will invade disturbed meadows and roadsides and grows vigorously from underground rhizomes, or roots. The rhizome is really deep underground—farther down than the length of your spade blade. I encouraged one that appeared several years ago and now I can’t get rid of it. But I’m going to stop trying to get rid of it. I will let it come up, bloom, and then pull off the fluffy seed pods. Why would I make this rash decision? Because the Monarch butterfly uses the leaves to lay her eggs. As the eggs mature into the distinctive green caterpillars, they eat the leaves before they undergo the metamorphosis which turns them into another butterfly to continue on their journey to Mexico. The leaves are poisonous, but this is the only food source for the caterpillars. While they themselves do not die from eating the leaves, the toxins make the caterpillars poisonous to predators -- a nice trick!

The Monarch population began to decline when farmers began to plant soy and corn on large tracts of land. To these butterflies, a monocrop is a wasteland because in order to plant corn and soy efficiently all the weeds needed to be killed with herbicides and this led to starvation for the butterfly larva which can only thrive on milkweed. One article has described this decline as 'nothing short of a massacre. Nearly a billion butterflies have vanished since 1990.'

Here is a relatively new development: people are being encouraged to grow milkweed for Monarchs now—in fact there may be a shortage of seeds! Here are some other varieties of milkweed that are also good for Monarchs.

Asclepias tuberosa is distinctive for its orange color. The common name is butterfly weed, but not butterfly bush! That shrub with its purple or white flowers is now considered invasive and is discouraged. Its flowers are attractive, but when it appears along the roadside it is taking the space of a native wildflower or weed that would be more beneficial to insects. You can’t miss the butterfly weed with its bright orange flowers—it is a native wildflower and also grows in disturbed areas. Be aware that this variety is very late to break the soil in the spring. It's a good idea to have a plant tag to remind yourself that it will eventually appear in late May.

Asclepias incarnata is also known as swamp milkweed. The leaves are narrow and pointed with narrow, pointed seed pods. The flowers are showy red-pink clusters and the plant prefers moist conditions, but in my garden it grows alongside other milkweeds. It blooms in June-July. Another variety is white flowering ‘Ice Ballet.’

Asclepias verticillata or whorled milkweed is another variety—very different from the above plants. It is a single-stemmed, unbranched perennial, 1-3 ft. tall. The narrow, linear leaves are whorled along the stem. Small, greenish-white flowers occur in flat-topped clusters on the upper part of the stem. Because of its toxicity to livestock, this plant is considered a weed in range areas, but it is a good addition to your pollinator garden.

These are just a few of the milkweed varieties. They are all perennials and native to this area and they are all deer resistant. They are all in my garden; all do well; all attract butterflies. In fact the Monarch is not the only butterfly to be attracted. Milkweed entices swallowtails, painted ladies, American ladies, red admirals, fritillaries and hairstreaks for the nectar. Hummingbirds and hummingbird moths are also visitors.

During WWII, the white, milky sap of the milkweed family plants were used experimentally to provide a rubber substitute. The silk produced by the seed pods was also used as a substitute for kapok in flotation devices for many years. If you were a child in the 40s, you may remember collecting milkweed pods as a way of helping the war effort.

Milkweed plants should be an important part of your pollinator garden. Monarchs are not the only pollinator to need native plants for nectar and pollen. We, as gardeners, must step up our efforts to provide habitat for all pollinators since most of our food needs pollination in order to mature. One of every three bites we eat is pollinated by an insect or animal!

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