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How to care for Butterfly Weed (Asclepias tuberosa)

Canadian yellow butterfly weed with flowers on green stalks
Asclepias tuberosa

As we grow closer to a more sustainable future, gardeners have become more discerning in what they purchase from the local nursery and what they plant in their gardens. When you think about butterflies and milkweed, most likely, the pink small flowered plant comes to mind. However, there is a difference between milkweed and butterfly weed.

Butterfly weed (Asclepias tuberosa) is a specific species of milkweed, belonging to the Asclepias genus. While milkweed is a broader term encompassing various species within the Asclepias genus, butterfly weed refers specifically to Asclepias tuberosa.

Here are some key differences between butterfly weed and other milkweed species:

  • Appearance: Butterfly weed is a perennial herbaceous plant that typically reaches a height of 1 to 3 feet (30 to 90 cm). It has clusters of bright orange to yellow-orange flowers arranged in umbels at the top of the stems. The flowers are flat-topped and have five petals. The foliage is narrow and lance-shaped.

  • Habitat: Butterfly weed is native to North America and can be found in various habitats, including prairies, meadows, and open fields. It prefers well-drained soil and is often found in sunny locations.

  • Growth habit: Butterfly weed has a clumping growth habit, with multiple stems arising from a central root crown. It does not spread aggressively through rhizomes like some other milkweed species.

  • Butterfly attraction: As the name suggests, butterfly weed is highly attractive to butterflies, including monarch butterflies. It serves as a valuable nectar source for adult butterflies and provides a host plant for monarch butterfly larvae.

  • Seed production: Butterfly weed produces distinctive seed pods that are long, narrow, and erect. The pods contain numerous flat seeds with a tuft of silky hairs (pappus) attached, aiding in wind dispersal.

It's worth noting that while butterfly weed is not considered invasive, some other milkweed species, such as common milkweed (Asclepias syriaca), can exhibit invasive characteristics in certain regions.

Types of milkweed

While milkweed generally benefits Ontario gardens, only some varieties are equally suitable for some gardens. It's vital to choose milkweed species native to your specific region in Ontario. Here are a few native milkweed species commonly found in Ontario:

  1. Common Milkweed (Asclepias syriaca): Ontario's most widespread milkweed species. It has large, pinkish-purple flowers and provides ample nectar for pollinators. Common Milkweed is a host plant for Monarch butterflies.

  2. Swamp Milkweed (Asclepias incarnata): Swamp Milkweed thrives in moist or wet areas and has attractive clusters of pink flowers. It is well-suited for gardens with wetter soil conditions and serves as a host plant for Monarch butterflies.

  3. Butterfly Milkweed (Asclepias tuberosa): This species has vibrant orange flowers and prefers dry to medium-moisture soil. It is a popular garden choice due to its striking colour and ability to attract butterflies, including Monarchs.

These native milkweed species are well-adapted to Ontario's climate and provide the necessary resources for Monarch butterflies and other pollinators. They are generally easy to grow and maintain. However, ensuring that the milkweed species you choose aligns with your specific garden conditions, such as soil moisture levels, sunlight exposure, and available space, is essential.

Mexican milkweed with yellow, orange and red flowers
Asclepias curassavica

It's worth noting that some non-native milkweed species, such as Tropical Milkweed (Asclepias curassavica), have been introduced in Ontario. While these species can provide nectar and food for Monarchs, they may pose certain risks, such as disrupting the natural migration patterns of Monarchs and potentially spreading diseases. Therefore, it is generally recommended to prioritize native milkweed species for Ontario gardens. However, most gardeners have found that the non-native species are used as an annual, dying in the cold winters.

Milkweed plants contain toxic compounds that can be harmful if ingested by humans or animals.

The toxins found in milkweed are known as cardiac glycosides, which can affect the heart and other organs. While milkweed is an essential food source for Monarch butterfly caterpillars, they have evolved to tolerate and even sequester these toxins, which make them unpalatable to most predators. However, these toxins can adversely affect other organisms, including humans and pets. It's essential to exercise caution when handling milkweed plants and to prevent ingestion by children, pets, or livestock. Avoid touching your face or eyes after handling milkweed without washing your hands, as the sap can cause skin irritation.

common milkweed with pink flowers on a tall green stem
Asclepias syriaca

If you have concerns about the potential toxicity of milkweed, it's advisable to consult with local gardening resources, native plant nurseries, or conservation organizations for specific guidance. They can provide more detailed information on the toxicity levels of different milkweed species and offer recommendations for safe handling and planting practices.

So now that you've decided on a native plant for your garden to attract butterflies, here are some key points on how to take care of your butterfly weed:

How to grow and take care of butterfly weed:

Yellow butterfly weed with a bug on it
Asclepias tuberosa

To grow butterfly weed (Asclepias tuberosa) in Ontario, you can follow these steps:

  1. Choose a suitable location: Select a sunny spot in your garden with well-drained soil. Butterfly weed prefers full sun and doesn't tolerate wet or waterlogged conditions.

  2. Prepare the soil: Before planting, loosen the soil and remove any weeds or grass from the area. To improve its fertility and drainage, you can amend the soil with organic matter, such as compost.

  3. Sow seeds or plant seedlings: You have two options for growing butterfly weed: sowing seeds directly in the garden or planting seedlings.

    • Sowing seeds: In early spring, scatter the seeds on the prepared soil surface and gently press them into the soil. Keep the soil consistently moist until germination, typically taking 2 to 3 weeks. Thin the seedlings to provide enough space for each plant to grow.

    • Planting seedlings: You can purchase young butterfly weed plants from a nursery. Dig a hole slightly larger than the seedling's root ball and place it in the hole. Backfill the hole with soil, firm it gently around the plant, and water thoroughly.

  4. Watering and maintenance: Keep the soil evenly moist but not waterlogged during the establishment period. Once the plants are established, butterfly weed is relatively drought-tolerant. Water the plants during dry periods to ensure healthy growth.

  5. Mulch and weed control: Apply a layer of organic mulch, such as straw or wood chips, around the plants to suppress weeds and conserve soil moisture. Avoid placing the mulch directly against the stems to prevent rotting.

  6. Pruning and deadheading: In late fall or early spring, you can cut back the stems of butterfly weed to the ground. This helps remove dead foliage and promotes vigorous growth in the following season. Deadhead the spent flowers throughout the growing season to encourage continuous blooming and prevent self-seeding.

  7. Monarch butterfly habitat: Butterfly weed is an important host plant for monarch butterfly larvae. By planting butterfly weed, you create suitable habitat for monarch butterflies. Ensure that you have enough space to accommodate caterpillars without compromising the overall appearance of your garden.

Remember that butterfly weed is a native plant and benefits pollinators, particularly monarch butterflies. By providing a suitable environment for butterfly weed to thrive, you contribute to conserving these crucial species.

Photo's supplied by one of our members, D.W. !! THANK YOU !!

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