Planting Milkweed Seeds

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Planting milkweed seeds can be challenging if you are not aware of some key planting requirements for milkweed. We have seen in the past years an explosion of gardeners who want to plant milkweed seeds in their gardens to support a healthy population of pollinators. Milkweed seeds can be more finicky than other seeds. Because of that, we have also seen many issues arise from gardeners who are not successful in planting milkweed seeds. Worry no more! We have all the information you need to know here.

Common Milkweed Plant

Types of Milkweed Seeds

Milkweed is a group of plants with many different species. Each region of the United States has native milkweed that has adapted to grow well in that region’s growing conditions. You can imagine that our dry, hot climate would not be suitable for a milkweed species adapted to growing in the humid swamps of Florida. Because of that, it’s important to know what varieties are native to your region.

Although you can grow a number of milkweed varieties in your garden, that butterflies and pollinators will surely appreciate, the best varieties are those that can grow easily and happily in your conditions. To help select the milkweed that is best for you, here is a quick cheat sheet:

Planting Milkweed Seeds in California & Dry Areas
Common Name Botanical Name Best Planting Area
Narrowleaf or Mexican Whorled Milkweed Asclepias fascicularis Dry Climates and Plains in California and Baja California
Showy Milkweed Asclepias speciosa Savannahs and Prairies
Desert Milkweed Asclepias erosa Desert Regions
California Milkweed Asclepias californica Grassy Areas
Heartleaf Milkweed Asclepias cordifolia Rocky Slopes
Woolly Milkweed Asclepias vestita Dry Areas and Plains
Woolly Pod Milkweed Asclepias eriocarpa Clay Soils and Dry Areas
Planting Milkweed Seeds in Arizona
Common Name Botanical Name Best Planting area
Butterfly Weed Asclepias tuberosa Well Drained Soils
Antelope Horns Milkweed Asclepias asperula Desert and Sandy Areas
Rush Milkweed Asclepias subulata Desert
Arizona Milkweed Asclepias angustifolia Riparian Areas and Canyons
Planting Milkweed Seeds in the Northeast
Common Name Botanical Name Best Planting Area
Common Milkweed Asclepias syriaca Well Drained Soils
Swamp Milkweed Asclepias incarnata Damp, Marshy Areas
Planting Milkweed Seeds in Texas and Oklahoma (South Central)
Common Name Botanical Name Best Planting Area
Green Antelopehorn Milkweed Asclepias viridis Dry Areas and Prairies
Antelope Horns Milkweed Asclepias asperula Desert and Sandy Areas
Zizotes Milkweed Asclepias oenotheroides Sandy/Rocky Prairies and Fields
Choosing What Milkweed Seeds to Plant in Your Area

While many of these species will grow in several areas of the United States and can thrive in your garden, the easiest and best way to plant milkweed seeds for the protection and encouragement of monarchs is to plant milkweeds that are native to your area. Tropical milkweed or Asclepias curassavica has been introduced to many parts of the United States. There is concern that its constant growing habit can cause butterflies to reproduce outside of their normal period, disrupt migratory patterns, and increase the transmission and virulence of the protozoan parasite Ophryocystis elektroscirrha (OE). ( If you have planted tropical milkweed in your garden, make sure that you cut it down to the ground after summer has passed to encourage the migration of butterflies.

Tropical Milkweed with monarch

How to Grow Milkweed from Seed in Zones 9 and 10

For those of us in Zones 9 and 10, you want to focus on planting the milkweed species listed above for California and dry areas. These seeds are very slow-growing and can benefit from cold stratification. This process is very simple. Place seeds in clean, moist paper towels in a clean container in the fridge for 4–8 weeks prior to planting. In our experience, this exposure to the cold allows for even more germination in the seed trays. Still, it does not make the germination process quicker. Patience is key when germinating milkweed seeds.

How to Plant Milkweed Seeds

Because of the slow nature of the germination process, when you are planting milkweed seeds, it’s best to sow the seeds in a high-quality planting mix with a bottom tray for watering. Bottom watering allows moisture to be wicked up through the soil by adding water to a bottom tray that the pot sits upon. This process helps discourage and manage algae and other soil fungal diseases that can become an issue with slow germinating seeds. Because the seeds will be sitting in moist soil for 3–4 weeks, you want to manage algae and soil fungus so that your seeds do not rot or become killed by the fungus.

Transplanting Milkweed Plants

Transplanting milkweed plants should only be done after the threat of frost is gone. You also should avoid transplanting milkweed if prolonged excessive heat or Santa Ana conditions are present. Transplant into moist soil and provide irrigation if there is no rainfall during the establishment period. It is vital that you prep your planting site before transplanting. Removing any competing weeds and light soil cultivation can help the transplants establish. Transplanting of milkweed plants should occur when the seedlings have outgrown their containers and start to reach the bottom of the tray. The roots will “air prune” and begin to stimulate lateral root development. This is important for healthy transplanting.

irrigation system

Management of Milkweed Plants Through the Growing Season

Each milkweed species has slightly different growing habits and requirements. But as a general rule of thumb, growers of milkweed plants should work to reduce competition from other weeds and avoid any use of insecticides. Hand-pulling weeds and light cultivation is best to manage the weed population. As your plants grow, you can watch butterflies appear, reproduce, and migrate. Planting native milkweed in your garden can help ensure you are a part of this magical miracle!

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