Help monarch butterflies by safely adding milkweed to your outdoor spaces

You can still do it while keeping your pets and other wildlife safe.
monarch butterfly on milkweed
Monarch butterflies have been declared endangered internationally, but they are still not legally protected in the US. Lasclay / Unsplash

In recent years, the monarch butterfly population has decreased by more than 80 percent. A lack of milkweed is one of the major causes of this decline, as the plant is the only food source for the species’ larvae and caterpillars, and the only place monarchs will lay their eggs. 

Planting milkweed in your own outdoor spaces is not only a way to help the butterflies, but it’ll also upgrade your garden or windowsill with beautiful, low-maintenance wildflowers. You can get seeds from marketplaces such as Amazon, but getting them from non-profit organizations like Save Our Monarchs or the Live Monarch Educational Foundation, will allow you to get seeds while supporting conservation efforts at the same time. 

Fall and spring are great times to plant milkweed, and even though this plant has an arguably undeserved bad rap amongst pet owners, there are ways you can incorporate it into your garden safely. 

Plant milkweed between cement slabs

Most milkweed species are easy to grow and maintain. A native wildflower to North America, milkweed can grow and thrive in just about any environment or climate on the continent, says Charles van Rees, an ecologist, conservationist, and founder of the blog, Gulo in Nature. “This means that it can be a low-maintenance plant that won’t be a headache,” he says. 

Any seemingly inhospitable nook, including side yards, alleyways, or patios, can be home to milkweed—even if it’s surrounded by hardscapes like cement slabs. And your neighborhood’s furry residents shouldn’t worry if there are no walls or fencing around the area. Even though milkweed can be toxic to wildlife due to the cardenolide-rich sap it uses as a defense mechanism, it’s only dangerous in large quantities, and bugs that feed on it and become toxic themselves (like the monarchs and their offspring) have bright coloration that warns predators away, van Rees explains. Animals don’t usually eat milkweed unless they’re forced to—like when they’re corraled and have no other food available. Still, if you are neighbors to a lot of pets and wildlife in general, opt for variations such as Joe Pye weed, and stay away from the most toxic kind known as Utah milkweed.

[Related: To save monarch butterflies, we need more milkweed]

To plant milkweed between cement slabs, consider the amount of rain your geographic area typically gets in a year. Most milkweed species prefer sandy and well-drained soil says van Rees, and ground surrounded by concrete may not drain as easily. 

“If you have more waterlogged soils, look for moisture-tolerant species like the swamp milkweed,” he says. These plants “don’t mind wet feet.” 

Next, think about the amount of sunlight your plant would receive. Most milkweed species evolved in open meadows, so they adapted to thrive in full sunlight. Only a few species of milkweed like partial shade, like the purple milkweed (native to Eastern, Southern, and Midwestern United States) or the whorled milkweed (native to eastern North America). 

Regardless of the variety, plant your milkweed seeds under 1/4 of an inch of soil and half an inch apart. Finally, water the area frequently until the plants begin to sprout to ensure they take root.

Add milkweed to planters or flowerpots

Milkweed works great in a container, as it can thrive easily and safely away from your dog, says Kevin Lenhart, design director at Yardzen, a residential landscaping company founded in California.

“Cats might pose a challenge,” he laughs. 

Some species, like common milkweed, can self-propagate through underground rhizomes, which allows them to spread aggressively even without the help of pollinators. Keeping the plant in a flowerpot can protect your pets’ eyes by preventing milkweed from spreading unchecked to spots your fur babies regularly hang out at. Most milkweed species have a milky white sap that can irritate eyes, Lenhart explains. “But milkweed getting in your dog’s eyes is rare,” and wouldn’t impact your animal’s health seriously, he says. 

To plant milkweed, choose a plastic container. While other materials work just as well, plastic is lighter, which will allow you to move the plant easily indoors for winter storage. Size is also important. Prefer spacious and deep containers around 10- to 12-inches tall and 5-inches wide, as milkweed root systems tend to grow large. You should also make sure your pot has a drainage hole to prevent the plant from becoming waterlogged. 

If you’ll be planting your milkweed in the Fall, you can put the seeds straight into the planter, but if you’ll be waiting for Spring, garden experts recommend head-starting your seeds in little cups with soil. Keep them indoors before moving them outdoors into a bigger planter, says van Rees. 

Plant your milkweed seeds by poking shallow holes in the pot’s soil with your finger and adding the seeds. Continue to water the plant until it sprouts.

Plant milkweed in large patches

Because it’s so prolific, milkweed is great groundcover and perfect to populate large patches of soil and prevent erosion. Plus, milkweed produces a lot of flowers, so you would be creating a big nourishing habitat for monarchs and other nectar-seeking pollinators. 

But the problem with large patches of milkweed is that there’s a lot of it in one place, making it a large risk for pets and other wildlife that might visit you and have a snack. 

[Related: The monarch butterfly is scientifically endangered. So why isn’t it legally protected yet?]

“Wild animals learn after one bite that milkweed isn’t good to eat,” says Ellen Jacquart, botanist and president of the Indiana Native Plant Society. “Most pets would react the same—that milky sap tastes awful!” 

Still, you should prevent any accidental ingestion of milkweed by fencing off the area. To do this, make sure the fence or protection you install is tall enough to keep pets out. A 24-inch barrier will generally dissuade most dogs from leaping into a patch of milkweed. 

Choose native milkweed

If you’re planting a large patch of milkweed, opt for native varieties. In fact, let this be your goal, says Jacquart, as native milkweed will offer monarch butterflies the most benefits. 

“Native plants offer exponentially more value than plants that are not native,” says Lenhart. This is because native species co-evolved with local animals, learning with time to be best pals with them as they both changed, he explains. 

Variety is also a plus, as grouping different kinds of milkweed together seem to attract more pollinators, Jacquart explains. As long as all the species you choose are native to your area, you can plant as many as you want. 

“It’s important to realize that there are many species of milkweed. All can serve as host plants [for monarch butterflies],” Jacquart says. 

Start your planting now and by Spring you’ll hopefully enjoy a garden filled with beautiful butterflies and other helpful pollinators. You won’t only be getting a pretty landscape, but you’ll also be helping nature thrive.