Growing Narrow Leaf Milkweed From Seed

Milkweed is a perennial best started in early spring and summer - March through July in California

To grow milkweed in small pots, first gather materials: plug trays or 4” pots, cactus mix or potting soil with added perlite, narrow leaf milkweed seeds (Larnerseed.com is a good source)

1. Fill containers almost to the top with potting mix
2. Soak the soil thoroughly
3. Make a small hole ¼” deep and drop 1-2 seeds (for the plug tray) or make 3-4 evenly spaced holes for the 4” pots and drop 1-2 seeds in each
4. Cover the holes and press damp soil to close air gaps
5. Put pots out in full sun or under grow lights and water every few days if weather is mild, or daily if it is hot
6. When seeds emerge in a few weeks, continue to water frequently to prevent drying out
7. When plants are 2-3” tall, plant in a cleared area in the yard, in masses to ensure adequate food for monarch caterpillars. A 5’ x 5’ space is a good start. Each plant can get as large as 12” circumference by 4’ tall. One or two caterpillars can eat a whole plant.
8. Consider putting a ring of stones around your milkweed patch to mark the spot when the plants die back (go dormant) in the fall

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To plant directly in the ground, make sure you have cleared a space in full sun, and removed any weeds that would compete with the milkweed. You might choose to add cactus mix to your soil to improve drainage. Then plant the seeds and water, as above.

Finally, you could plant milkweed in very large pots, but just make sure you plant a lot to avoid an ‘ecological trap’ where you attract a monarch to lay her eggs, but don’t provide adequate food for the caterpillars.

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Note: never use pesticides, even ‘organic’ ones, in your garden as they will kill the caterpillars and other insects in your delicate ecosystem. Avoid herbicides as well since they damage the soil and the important microbes that make your garden healthy. 

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Milkweed dies back in the fall, but comes back in spring, typically stronger each year. Pictured to the right is a ring of pebbles marking a dormant milkweed patch, so it won’t get accidentally overplanted. Also pictured is a blooming narrow leaf milkweed in a large pot, and a monarch caterpillar. When your milkweed goes to seed, you can collect these and share them with neighbors and friends, creating a ‘monarch corridor’ in your neighborhood.

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Thank you for helping these iconic butterflies make a comeback!

Jennifer Dirking

Ecogardenista@gmail.com

EcoGardenista.org

Images (CC-BY-NC Jennifer Dirking except Monarch on Narrowleaf Milkweed (CC-BY-NC) Erica Fleniken