Narrow Leaf Milkweed (Asclepias fascicularis)

Usually when a plant has the word “weed” as part of it’s name, it doesn’t immediately attract itself to the typical gardener as a good candidate for their landscape.  But this is one of those that should be given a second look.

20180611_182549(All links open a new page, so you won’t lose your spot when you look around!  Get information on gardening and cultural traditions, recipes, stories, and more!)

*A handy growing summary chart is at the end of the article.*

20180709_080346Many people are familiar with the fact that milkweed is a food source for monarch butterflies.  What some may not realize is that there are multiple milkweed species, and that milkweed is the exclusive food source for the monarch larvae, whereas the adults can get nectar from a variety of plant sources.

20180611_182516Sadly, monarchs are on a serious decline across the country, much of it due to the loss of milkweed in the environment as land is cleared for housing, agriculture, etc.  Thankfully, as awareness of the need for protecting biodiversity has increased,  more people have been looking to include milkweed into their landscapes.

These are the juvenile milkweed bugs that help keep my plant under control.

In addition to being a necessary food source for monarchs, milkweeds are a great nectar and pollen source for so many other pollinators and critters in general.  They also produce very pretty flowers and make a lovely contribution to a mixed flower landscape.  Most are also drought and heat tolerant, and can grow in fairly poor soil.

The variety I have is Narrow Leaf Milkweed (also known as Mexican Whorled Milkweed, and Narrow Leaved Milkweed) and is native to a variety of dryer habitats across the western United States and parts of Baja California.  It produces a profusion of flower clusters towards the tips of the stalks that are light pink to light lavender in color.  The stalks are narrow, and as the name implies, have several narrow leaves that project out.  It can reach heights of 4 to 5 feet, and have a spread of 3 to 4 feet.  The plant does die back in the winter when temperatures start dipping near frost levels, but will return even bigger in the spring when the soil warms.

These are the adult milkweed bug, creepy looking, but harmless to all other plants.

I do have a word of warning, though.  This variety of milkweed can spread by underground roots and produces a profusion of seeds.  However, with regular plucking of sprouts as they appear in areas you don’t want them and removal of flowers after they have bloomed, you can easily keep it under control.  Not only that, if you are lucky enough to attract monarchs to your yard, the larvae will very readily keep your plants in check.

I haven’t had any monarchs, yet, but I have had another milkweed predator helping me out.  It turns out there are other organisms that feed exclusively on milkweed, and one has made their home in my yard.  Milkweed bugs (Oncopeltus fasciatus) have been finding my plant each year now.  They have been beneficial because they keep the spread of my milkweed under control, and have not shown any signs, as of now, of being destructive.

20180628_184649Another word of warning about any variety of milkweed is that the sap is toxic.  The organisms that feed on them have an ability to either breakdown that toxic sap, or incorporate it into their tissues for protection from predators.  Your pets are not likely in any danger, but young children should be cautioned.  To help avoid potential problems, plant your milkweed away from plants that are consumed, that way children don’t associate it with other types of edible plants.  Other wild organisms will have learned or instinctually know to leave it alone.

Plant Summary:

  • Perennial
  • Deciduous: leaves and stems may remain in areas with mild winters, but will otherwise die back to the ground
  • Height: up to 4-5 feet
  • Width: up to 2-3 feet, but taller stems have a tendency to flop over
  • Sun: full sun
  • Water: drought tolerant, but will do best with some water during prolonged hot and dry weather, does not like soggy soil
  • Soil pH: neutral to slightly acidic
  • Soil type: can tolerate various soil types, including heavy clay
  • Key nutrients: fertilize as you would for other flowers, but likely won’t be needed
  • Planting time: can be started from seeds (follow package directions), or transplants can be started in early spring to allow for root development before it gets too hot and dry
  • Zones: 3-11


7 thoughts on “Narrow Leaf Milkweed (Asclepias fascicularis)

  1. This is more how I thought milkweed looked. All these new garden varieties look so foreign. I thought that I had remembered it wrong. Those that naturalized along the creeks of the Santa Clara Valley along time ago looked more like those in these pictures. They really seemed to be quite at home here, as if native. I don’t know where they came from or why they were imported, or if they were imported intentionally. Nowadays, I don’t know what happened to them. I have not seen one in many years.

    Liked by 1 person

    1. There are actually over 100 different types of milkweed in North America. This type is native to the Western US, including California, but wouldn’t naturally be found elsewhere. I don’t know that there are a lot of new cultivated varieties out there. Most of what I have seen available are the wild-types that are native to different areas of the country. They can look really different from one another, but are all still Asclepias.

      Liked by 1 person

      1. I suppose it must be easier than it used to be before we used the internet. I was amazed at how easy it was to find seed for many of the rare species of Yucca.


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