Collected Milkweed Pod and Seeds: Best Germination Rate Method?

Question: Hello U of MD extension Office Expert....I have attached a photo of milkweed seeds I collected today. They had been released from their pod and were on the stem of an adjacent plant. There is also a pod I collected that was on the same stem as the one that had opened and was empty. What is the most successful way to grow milkweed in the garden from collected seeds? Overwintering in the garden bed by planting now? Or bringing the seeds inside and cold treating them in the refrigerator and planting in the spring?
Thank you for your help.

Sincerely,
Jonathan

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied October 22, 2024, 3:03 PM EDT
response: As it happens, we will soon be publishing a new web page about collecting and sowing native plant seeds (a general tips page, as it can't go into detail for each of the many native species Maryland has). For now, we do have some recorded Master Gardener presentations on the subject that might be helpful, plus a blog post about winter sowing.  Knowing which species of plant you're propagating is the first step, and by its appearance, we'd guess that this is Common Milkweed (Asclepias syriaca), is that correct? (As opposed to Butterfly Weed, Asclepias tuberosa, Swamp Milkweed, Asclepias incarnata, or another local milkweed species. It might not matter much in this instance, but we wanted to check.)  Native seed supply companies online often provide tips for storing and sowing certain species, but in general, you could either use the fridge to give them a stratification period (winter chilling) or sow them outdoors for the same effect, either in sheltered containers (like a cut-open plastic milk jug) or directly into the ground. The challenge of outdoor sowing is protecting the seed from fall and winter predation by wildlife like birds and mice.  William Cullina, author of the book The New England Wildflower Society Guide to Growing and Propagating Wildflowers of the United States and Canada, notes for milkweed: "Most of the species germinate easily if surface-sown and given a cold period. Seed germinates without a cold period, but it is slow and sporadic." His germination conditions notes include (a) seed will germinate within 4 weeks if sown at 70 degrees F; (b) seed will germinate upon shifting to 70 degrees F after 90 days of moist, cold stratification at 40 degrees F; and (c) seed requires light to germinate.  Therefore, you can either stratify or not, though it sounds like stratification is preferable. Plus, since there isn't time to have them germinate now before they'd need to go dormant, chilling should keep them reasonably fresh until they can germinate in spring. Since these seeds need to stay moist, store them in the fridge (unless sowing outside) with a source of moisture so seeds stay humid but not soggy. When ready to sow them either directly onto the ground or into containers, they should stay on the surface (or close enough to not be buried by soil) since they won't sprout if they don't get enough light. While you could start them early indoors once the chilling minimum period is met, that would entail using grow lights to give them enough energy for growth, which might be cost- or space-prohibitive. If overwintered outdoors, at least they will germinate more "on-time" and be less out-of-sync once the weather warms.  Miri

responder: The Question Asker Replied October 22, 2024, 5:55 PM EDT
response: Thank you, Miri! Yes...this is seed from common milkweed. I will take a look at the presentations and the blog post. Can you send me a link to the new web page about native plant seed collecting when it is published? Thanks so much for your help!   Sincerely,  Don Giovanni

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied October 23, 2024, 9:41 AM EDT
response: You're welcome.  We don't know when the new page will be published yet and might not be able to share it individually with everyone that might want to be notified, but it might be featured in the "hot topics" area of the HGIC home page, and/or featured in a HGIC social media post. A search on the UME website for keywords like "winter sowing" or "native" will also almost certainly bring up the new page as well. If you receive the HGIC newsletter via email, new web pages are also featured there.  Miri