My Experiences With Growing Low Milkweed (Asclepias ovalifolia)
- Oanh Nguyễn
- Aug 3
- 2 min read
Originally published in the November/December 2023 issue of the WildFlower News
by Liz Deleeuw
Low milkweed can be a challenge to grow out for planting in the garden. The germination can be extremely variable but I have often achieved successful germination. The problem for me is keeping plants alive and viable. More on that below.
I stratify my seeds for six weeks in the fridge. I use a 50/50 mix of peat moss and sand. I mix one part seed to five parts of the mixture in a baggie. I add just enough moisture to dampen the mix. While the baggie is in the fridge I check it routinely to see if there is germination happening, but there is usually no germination before the six weeks are up
At the six-week mark I spread the mixture thickly on top of 5" pots and put them in my bay window or under grow lights. The link below recommends planting other milkweed species at 1 to 2 cm depth. I have never done this because I rely on the thickness of my mixture to provide different depths for the seeds. Planting them a bit deeper, covering some pots with more potting medium, may be worth a try.
Once germinated, I harden off the seedlings by putting them outside in the shade for progressively longer periods of time, while still bringing them in overnight. Once they are acclimatized to the outdoors, I put the pots into my backyard nursery where they get watered and tended.
Many seedlings will die back at dierent times during the growing season. I keep them all as some may come back after the winter. While I let some established rst-year seedlings go for planting into gardens, I like to keep the majority of the pots in my nursery and overwinter them. If the peat pots become weak I plant the whole thing into a larger plastic pot over the winter.
In the spring, the second-year low milkweed plants that come up have the best chance of survival. I keep the rest of the (seemingly) empty pots until later in the season (in case they should sprout up again) but compost them before fall if they show no signs of life.
"Due to their rhizomatous nature, milkweeds do not develop many fibrous roots and their root plugs often fall apart during transplanting…... (Therefore, Jiffy® pellets ... or containers with other types of stabilized growing media are recommended." IPPS Combined Proceedings Volume 64 (2014) p. 302 (usda.gov)) This confirms my experience.
If you are planting your first-year seedlings into the garden, cut back some of the peat pot to allow for root growth. The key is not to disturb the roots. If you are planting second-year plants you will not need to cut the peat pot. The decomposing peat pot will make it easier to prevent disturbing the roots.
After planting out into the garden there is still a chance that the plants may die back. Keep them marked and wait for them next year. While I have never been able to keep low milkweed growing in my garden, ENPS has good populations at the Muttart and John Janzen demonstration beds.
