Seed collection for Asclepias spp. is more straight forward than some other native wildflower species. We like to use organza drawstring bags over unopened seed pods. This way, the pods can continue to mature, and when they split open, the organza bags prevent the seed from blowing away (pro tip this also works for keeping caterpillars out of tomato fruit if you pick appropriately sized bags for the variety of tomato you are growing).
Once the seed pods split open, revealing mature seed, you can simply snip the pod from the plant (leave the bag on to transport), then when you are ready, remove the husk, then fluff from each seed. We like to lay the seeds out on a paper towel or in a fine mesh tray or a basket for a few days to ensure they are completely dry before storage. After that, the seeds can go into a sealed container. We like to use glass jars with cork stoppers.
To prepare the seeds for germination, Asclepias spp. benefit from cold moist stratification. All this means is that the seeds germinate in greater numbers if they are subjected to conditions that simulate winter weather for a period of time. There are all kinds of methods of stratification out there but for me, simple is better. I just moisten a paper towel with a spray bottle, arrange my seeds, and fold them in the towel. The whole thing goes into a zipper sandwich bag, and into the fridge. Don’t forget to write the date they go into the fridge!
When I first started working with milkweed seeds in a more controlled environment (as opposed to just broadcasting the seeds outdoors), I simply poked the pointy side down into a rehydrated seed starting pellet. Turns out, milkweed seeds are “directional”. For me, when I poke them pointy side down into a substrate, they grow upside down. These days, I place them broad-side horizontal, then put a light layer of substrate over the top, and press down gently. Pressing the substrate gently over the seed makes it easier for the rootlets to grip the substrate and grow strong.
I also have tried coating the seed in mycorrhiza, though research suggests there may be some fungal specificity to what species of plant roots they will colonize. I haven’t seen a significant difference in germination rate if you skip this step though. After seeds are placed in substrate, placing them under a grow light, with a heat mat really helps germination. I generally see activity within four days when using a heat mat. Don’t give up on seeds that don’t sprout though. Within the same species, some take much longer than others, and I haven’t really figured out why.
While seedlings are growing, I start getting them acclimated to being outdoors. I place them in a sheltered area out of full sun for a few hours at a time, monitoring how much they pout. If they start looking wilty, I bring them in. Just slowly increase the amount of time they spend outdoors (a covered porch works perfect). When seedlings reach about 4 inches of height, they’re typically well acclimated to being outside, and I transplant them into 4 inch nursery pots, and just let them do their thing. I ensure they are adjusted to being in more direct sunlight before leaving them outdoors continually.
Once milkweeds have been given time to establish a good root system (root threads may be observed peeking out the drainage holes at the bottom of the pots), they do pretty well being transplanted into the ground. Some even seem to do well directly from the seed starter pellet (I have put A. texana directly into the ground after reaching about four inches in height in the seed starter pellet, and it bloomed beautifully the following year).
It’s up to you to choose species that work well for your ecoregion, but don’t worry. We have tons of native species to choose from! Also, if you are local, Hambone’s Mercantile periodically has live plants available for pickup if you aren’t ready to try your hand at germination. Seeds can be purchased for shipping (as available) from our Etsy shop.
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