Milkweed is a drought-tolerant and deer-resistant perennial plant named for its milky latex sap. It is a great host plant for many beneficial insects including Monarch butterflies, bees, beetles, and lady beetles (ladybugs).
Other native milkweed species that are suitable for our climate are California milkweed (A.californica), woolly milkweed (A.vestita). woollypod milkweed (A. eriocarpa), and heartleaf milkweed (A. cordifolia), which is better suited to the Sierra foothills (2000 ft. elevation). The native milkweed species are not invasive.
Milkweed is the only plant on which the Monarch butterfly will lay eggs. If larvae hatch on your milkweed you might notice the plant's leaves being devoured by the caterpillar. Do not cut it back or pull it up. Once the caterpillar morphs into a butterfly the leaves will grow back.
Home gardeners can aid the Monarch population by adding milkweed to their landscape, pollinator garden, herb garden, or even a patio container. If you own a larger plot of land you might consider letting some of it remain wild, so that the wild nectar producing flowers are available not only for butterflies, but for other pollinators as well.
Milkweed commonly attracts a yellow aphid known as Oleander aphid. This aphid will not destroy the plant and will not infest nearby roses or vegetable gardens. It is plant specific: think of the Oleander aphid as food for the lady beetles. Avoid using pesticides or herbicides that might damage these breeding and feeding areas.
Milkweed is bitter flavored and unpalatable. It is recommended that you do not plant it near livestock as it can be toxic.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at (530) 538-7201. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.
- Author: Kathy Keatley Garvey
Dear Ms. Mantis,
We see you. You're trying to camouflage yourself, but we see you.
You're hanging out on a showy milkweed, Asclepias speciosa, trying to catch a butterfly or a bee.
So, will you try to nab a monarch? A Mama Monarch that's trying to lay her eggs on her host plant?
You know, the declining monarch population is on “life support,” as butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, says.
Ms. Mantis, we remember when one of your kin ambushed a monarch on our butterfly bush in September of 2015. Your kin ate the head, thorax and abdomen and discarded the wings. The wings fluttered to the ground. Yes, we know you have to eat, too. Everything in the garden eats.
But now that we have your attention, Ms. Mantis, would you kindly consider the following menu--à la carte, if you wish?
- Appetizing aphids
- Scrumptious stink bugs
- Magnificent milkweed bugs
- Crunchy cabbage white butterflies
- Luscious leaffooted bugs
Thank you, Ms. Mantis, for your kind attention to this culinary matter. If we may be of any future help in menu planning (it's important to consider the principles of adequacy, balance, calorie or energy control, nutrient density, moderation and variety), please let us know.
Signed,
The Gardeners
- Author: Kathy Keatley Garvey
We plant three species of milkweed (the host plant for the monarchs), but both the monarchs and the honey bees gravitate toward A. curassavica, a non-native. So do syrphid flies, carpenter bees, bumble bees, leafcutter bees and assorted other insects.
If you haven't heard, planting tropical milkweed is controversial. Scientific research shows that it disrupts the monarch migration patterns when it's planted outside its tropical range, and can lead to the spreading of OE, orophryocystiselektroscirrha, a protozoan parasite that infects monarch and queen butterflies. (See Exposure to Non-Native Tropical Milkweed Promotes Reproductive Development in Migratory Monarch Butterflies, published by the National Center for Biotechnology Information, U.S. National Library of Medicine, Bethesda, Md. Also see the Xerces Society for Invertebrate Conservation website on the issue.)
UC Davis alumnus and monarch expert Anurag Agrawal of Cornell University, the James A. Perkins Professor of Environmental Studies at Cornell University and the author of the celebrated book, Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and their Remarkable Story of Coevolution (2017 Princeton University), knows the controversy well.
"Tropical milkweed is an interesting and complex issue," he recently told us. "I love the plant for various reasons, but there is growing evidence that as it has become weedy (and self-seeding) in the southeastern United States and California. It is affecting monarchs, mostly by disrupting their migration. The key issue here is that when it is flowering 'out of season' this can be 'confusing' to monarchs. Having said this, we don't live in a pristine world, so my position is that we need moderation in the approach to tropical milkweed. It is certainly an easy plant to grow and monarchs can make good use of it during the caterpillar season. If you love the plant, go for it, but I would recommend cutting in back before the migratory season starts."
Agrawal received his doctorate from UC Davis. Read a review of his Monarchs and Milkweed book from the journal Ecology and read the first chapter here. You can order the book here.
Three Milkweed Species
We offer monarchs a choice of milkweed species in our Vacaville pollinator garden. In addition to the non-native A. curassavica, we plant two native species: narrowleaf milkweed, A. fascicularis, and showy milkweed, A. speciosa. In July, we collected 11 caterpillars from the narrowleaf milkweed; we rear them to adulthood and release them into the neighborhood. But in the numbers game, the tropical milkweed won. From July through today, we have collected a whopping 43 eggs or caterpillars from A. curassavica. How many from A. speciosa? Sadly, none.
As recommended, we cut back or remove the tropical milkweed before the migratory season. In the meantime, we grow it for three reasons: (1) for the monarchs (2) as a food source for other insects and (3) as an ornamental garden plant. We like the brilliant colors and the diversity of insects it attracts.
On one afternoon in late July, we photographed foraging honey bees on the spectacular blossoms. They just couldn't get enough of it.
Milkweed is a drought-tolerant and deer-resistant perennial plant named for its milky latex sap. It is a great host plant for many beneficial insects including Monarch butterflies, bees, beetles, and lady beetles (ladybugs).
Milkweed plants develop large fleshy seed pods which pop open when mature, freeing the seeds. Attached to the seeds are fine tufts of hair (called pappus or silk) which aid dispersal of the seeds: as the wind blows, it catches the silky hairs, carrying the seeds away from the plant. The seeds can be collected from the pods for later propagation or left alone to re-seed themselves. Milkweed can also be propagated from cuttings or root divisions.
Milkweed is the only plant on which the Monarch butterfly will lay eggs. If larvae hatch on your milkweed you might notice the plant's leaves being devoured by the caterpillar. Do not cut it back or pull it up. Once the caterpillar morphs into a butterfly the leaves will grow back.
Milkweed commonly attracts a yellow aphid known as Oleander aphid. This aphid will not destroy the plant and will not infest nearby roses or vegetable gardens. It is plant specific: think of the Oleander aphid as food for the lady beetles. Avoid using pesticides or herbicides that might damage these breeding and feeding areas.
Despite having the word ‘weed' in its name, milkweed can be an interesting addition to your home landscape. It is generally non-invasive and easy to grow and care for. Milkweed requires full sun. It will need some water until it is established. Some varieties will die back with a heavy frost or snow but will return in late spring. If the plant re-seeds itself, you can either leave the new plants in place or dig them up to share with neighbors.
For more information on area-specific native milkweed, and to purchase seed the Theodore Payne Foundation is an excellent source.
The UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu (preferred) or call (530) 538-7201.
- Author: Kathy Keatley Garvey
Picture this during National Pollinator Week: five monarch caterpillars and assorted honey bees sharing tropical milkweed.
It was love at first bite. Or love at first sip.
The 'cats kept munching and the bees kept foraging. Neither species seemed interested in the other.
But the adult monarchs definitely showed more interest in the tropical milkweed (Asclepias curassavica), a non-native, than the other two species, both natives, that we planted: the narrow leaf (A. fascicularis) and showy milkweed (A. speciosa).
They laid eggs only on the tropical milkweed, and so far, have produced five caterpillars.
The score to date:
Tropical milkweed: 5 caterpillars
Narrow leaf milkweed: 0
Showy milkweed: 0
Reminder: Folks planting the tropical milkweed in temperate zones (like here in Vacaville,Calif.) must remove or cut back the tropical milkweed by winter. "A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves," explains the Xerces Society for Invertebrate Conservation.
Yes, indeed. But meanwhile, we're witnessing untold sharing on the wildly popular tropical milkweed by not only monarch caterpillars but honey bees, syrphid flies, bumble bees, carpenter bees, leafcutter bees and sweat bees.
We gardeners and photographers are also drawn to the spectacular red, orange and yellow flowers that add both beauty and color to a cherished pollinator patch in the midst of the COVID-19 pandemic...and National Pollinator Week.