Plant of the Month for August 2023: Asclepias speciosa – Showy Milkweed
August 25, 2023
Our Plant of the Month for August, chosen by Gardens’ Supervisor Hannah Sweeney, is Showy Milkweed. Showy Milkweed can be found throughout the Western and Midwestern continental US. A favorite of Monarch butterflies, Asclepias ssp. - Milkweed species are the only plants that they lay their eggs on.
A single Showy Milkweed bloom head with its complex individual blooms, has the appearance of being delicate, and yet alien-looking, both at the same time.
Hannah says her reasons for choosing Showy Milkweed as the August Plant of the Month are: “I love that it's a CA native, it's a host plant to Monarch butterflies, and the bloom is so unique and beautiful. It's one of my favorite plants that we have in the gardens”.
To Hannah’s reasons, I would add that Showy Milkweed is an incredibly tough plant, re-sprouting from
the roots, not only with spring rain, but also after an incidental mowing or weed trimming or two early in the spring (don’t do this too late in spring though, you’ll be cutting off developing flower buds).
Also, Showy Milkweed is incredibly drought tolerant, once established. It grows in many areas locally with no available summer water. If it does grow in an area with no summer water, the plant will dry up and go into a summer dormancy. If you do choose to grow Showy Milkweed in a summer-dry area, you can cut back the stems after they dry out (wait until after the dried seed capsules split and their down-covered seeds, which look a bit like giant Dandelion seeds, float away on the breeze). Not to worry though, Milkweeds will re-sprout with the rain again in early spring.
A young Showy Milkweed planted in the California Garden from a one gallon pot that, with time and its vigorously spreading rhizomes, became the large patch (in the following photo) that grows there now.
Showy Milkweed, like all Asclepias ssp., contains alkaloids that, when ingested by caterpillars (butterfly and moth larvae) makes them taste horrible to predators and protects them from being eaten. Monarch butterflies, in particular, need Asclepias spp. to lay their eggs on, as it is the next generations’ sole larval food source. Luckily, species of Milkweeds grow across the US and into Mexico, making them available to Monarchs over a large territory.Planting species of Milkweeds that are native to, or adapted to, your area is key to creating a butterfly-friendly garden that is inclusive for Monarch butterflies. Creating a butterfly-friendly garden at homes, schools and businesses has never been more important, as wild habitat and habitat plants for Butterflies, and other critters, continues to dwindle.
Remember, butterflies are insects, so refrain from using insecticides in your garden if you want butterflies to flourish there. Yes, you will likely see foliage damage from chewing caterpillars; but if you don’t want to see the evidence of caterpillar grazing (as in a highly conspicuous area on the plant), you can just cut those overly-chewed leaves off. Leaves can grow back, but a dead caterpillar does not a butterfly make!
You can find a link to a list of drought-tolerant butterfly plants, including Showy Milkweed, on the top of our Nursery inventory list at: turtlebaynursery.org
Photos from Kellys’ Garden
The mature patch of Showy Milkweed growing in California Garden with one of our local Pipevine Swallowtail butterflies. Mature stands like this are breathtaking when in bloom! Plants spread reliably by underground root runners, called rhizomes.
The dried plant stalks of all Milkweeds, but especially Showy Milkweed, contain tough fibers in the dried stems. They were used by early people to make fabric and rope. There were other early uses that made Milkweed an all-around valuable plant (if you’re interested, look up more early uses of Showy Milkweed in the Plant Guide on the Asclepias speciosa information page at: plants.usda.gov).
Caring for Asclepias speciosa – Showy Milkweed in our area:
● Prefers growing in sunny areas. Not particular about soil type. Very drought-tolerant, don’t overwater.
● As with many CA native plants that go dormant in areas with no summer rain, if you want to prevent (or
delay) summer dormancy, after weekly summer establishment watering the first (usually) 1-3 years, the plants need deep watering at least 2 - 4 times monthly in summer to prevent (delay) the plant from going dormant.
Above: The mature patch of Showy Milkweed growing in California Garden with one of our local Pipevine Swallowtail butterflies. Mature stands like this are breathtaking when in bloom! Plants spread reliably by underground root runners, called rhizomes.
Available now at the Turtle Bay Nursery!
Showy Milkweed is a customer favorite, and always in propagation rotation in our Nursery. See the updated inventory list along with growing information:
Gardening or plant questions? Email us at: gardens@turtlebay.org
