Everything You Need to Know When Planting Butterfly Milkweed Seed
April 30, 2024

Everything You Need to Know When Planting Butterfly Milkweed Seed

Close-up of a butterfly milkweed seed

The perennial Asclepias tuberosa, commonly known as butterfly milkweed, adds a splash of color to any landscape and provides a critical food source for monarch caterpillars.

The plant’s vibrant orange and red blossoms offer a sustainable and environmentally friendly choice for experienced farmers and gardeners who want to enrich their land’s ecological value.

However, despite the plant’s adaptability to various climates and minimal irrigation needs, successfully planting butterfly milkweed is not without its challenges. We’ve put together a guide covering everything you need to know about this plant’s unique requirements.

Understanding Seed Dormancy and Germination Among Asclepias Species

The main challenge in successfully planting milkweed is the wide variability of seed dormancy characteristics within and among species.

Seed dormancy is a natural survival strategy that prevents seeds from germinating until conditions are favorable for the survival of the seedlings. In a natural setting, this mechanism ensures that germination occurs at an optimal time, reducing the risk of seedling mortality due to adverse weather conditions or insufficient resources.

When it comes to Asclepias, research has found significant variation not only between species but even among seeds from the same plant. This variability could affect the timing of germination, which in turn influences the competitive dynamics and survival of the seedlings.

For A. tuberosa, light has little to no effect on germination once seeds have undergone adequate cold stratification, suggesting that temperature and moisture are more critical factors​.

Ernst’s Cold Stratification Protocol

Farmers and researchers have developed protocols for stratifying butterfly milkweed seeds to compensate for the natural dormancy of Asclepias species. These protocols mimic the natural cold period a seed would experience over winter, breaking its dormancy and triggering germination.

At Ernst, we developed our own protocol for the cold stratification of milkweed seeds that looks like this:

  • In a Ziploc® baggie, mix three to five volumes of Quikrete Play Sand® brand sand with every volume of seed. We recommend this brand of sand as we have found the grain size to be very uniform.
  • Moisten the sand/seed mix with tap water so that it looks like wet sand at the beach.
  • Seal the baggie and place it into a refrigerator, but not the freezer, for up to three months.

After three months of stratification, the seeds will be ready to plant.

Overcoming Dormancy with Vegetative Propagation

Traditionally, A. tuberosa has been propagated through seeds. A method that, while effective, encounters challenges related to seed dormancy and germination variability.

Recent studies, however, have explored vegetative propagation techniques as a viable alternative for increasing production efficiency and genetic consistency among cultivated plants.

Here’s what we’ve learned from these studies:

Optimizing Environmental Conditions

Findings suggest that propagules exhibit optimal root and callus development when maintained in well-drained soils and exposed to 15 to 17 hours of daylight, with night/day temperatures ranging between 61–77°F.

These conditions help mitigate pathogen pressure and support the overall health and vigor of the developing plants.

Timing and Technique

Research suggests collecting stem cuttings 3 to 5 weeks prior to flower initiation or 3 to 4 weeks after dormancy break to maximize survivability and rooting success​.

Choosing Between Seeded vs. Vegetative Propagation

There are certain advantages to each method of propagation. Consider these factors when determining which method is right for your goals.

Seeded Propagation will result in genetic variation, which improves the plant’s resistance to changing environmental conditions. It’s also generally more scalable for large-scale restoration projects since it produces a large number of plants relatively inexpensively and efficiently.

Vegetative Propagation produces genetically identical offspring, which preserves desirable traits. This makes it an excellent choice for ornamental use or specific ecological functions. Certain vegetative techniques, such as stem cuttings, can also lead to faster establishment and growth compared to seeded methods, making it a good option for quickly establishing milkweed populations.

Ideal Planting Conditions For Butterfly Milkweed Seed

Planting times will vary by method. For seeds, sowing should follow a period of cold stratification, ideally in late fall to early spring.

If planting seedlings or cuttings, wait until the threat of frost has passed in spring, providing a full growing season for the plants to establish.


Milkweed thrives in well-drained soils. While it can tolerate a range of soil types, from sandy to clay, ensuring good drainage is key to preventing root rot and other water-related diseases.

For depleted soils, adding organic matter improves soil structure and nutrient content, promoting healthier growth.


Choose a sunny location where plants can receive at least six hours of direct sunlight daily.

Butterfly milkweed’s vibrant flowers and foliage are visually appealing and essential for supporting pollinators. Adequate spacing, approximately 18-24 inches apart, allows for proper air circulation and reduces competition for resources.

Pest Management For Butterfly Milkweed Seed

While milkweed is generally robust and resistant to many pests, some common issues can arise.

Common Pests

Physical removal with a water hose is sufficient to prevent damage to the plants from common pests such as aphids, whiteflies, and scale insects. This approach can also mitigate dust collection that exacerbates mite problems.

If an infestation becomes severe, targeted applications of insecticidal soap, neem oil, or systemic insecticides can be effective. However, caution is advised to prevent harm to beneficial insects or monarch larvae.

Disease Prevention

Ensuring good plant health through adequate soil drainage, avoiding overwatering, and removing infected plant material can significantly reduce the risk of pest infestations and fungal diseases. Cercospora Leaf Spot can be a major foliar disease problem for butterfly milkweed. Spacing plants 2’ apart with other plant species in between will reduce disease pressure.

These practices, combined with selecting planting sites with favorable conditions, can substantially improve disease prevention.

Butterfly Milkweed Seed Harvesting Tips

The main challenge of harvesting milkweed seeds is overcoming the seeds’ fluffy attachments.

Timing and Techniques

Avoid harvesting milkweed seeds too early; viable seeds are dark, not light brown or white.

To prevent pods from bursting open prematurely, use rubber bands, twist ties, or organza bags to contain the seeds until they’re ready to be harvested indoors. This method keeps the fluff contained and offers an aesthetically pleasing way to gift seeds.

Storage and Planting

Seeds should be stored in a refrigerator if they are to be planted in the spring, offering the cold stratification they need. Dry storage in paper or plastic bags helps prevent mold, and marking them ensures they are not mistakenly discarded.

North America’s Top Producers and Collectors Rely on Ernst’s Butterfly Milkweed Seeds

With proper stratification, well-drained soil, ample sunlight, and effective pest management, butterfly milkweed can be a gorgeous and ecologically friendly addition to any garden or restoration project.

For those interested in protecting monarch butterflies and anyone inspired to participate in the larger effort to protect the natural environment and preserve native plant populations, selecting high-quality seeds is paramount.

For 60 years, Ernst has been providing high-quality seeds, including a curated selection of butterfly milkweed seeds, and contributing to the restoration of North America’s natural ecology.

Interested in learning more about our seeds, including our butterfly milkweed? Contact our experts today.

© 2024 Ernst Conservation Seeds | Privacy Policy