How to get milkweed to germinate

I won’t lie, milkweed is a pain to get started. Once its germinated and a seedling, it’s an easy keeper. But it takes some knowledge to get there! Here are my tips from many a failed attempts over the years. Numerous seeds were tossed in this learning process! Cheers for a more successful experience than I had! And for context, I am in USDA Zone 6b.Getting started: Anatomy of a Seed
The most familiar characteristic of milkweeds is that its seeds are dispersed by the wind using a fantastic plume of fibers. This fluff is often called a “parachute” in grade school and a “coma” in botany.

FUN FACT ABOUT MILKWEED FLUFF

Did you know?

In World War II, Americans collected milkweed seed pods for the fluffy down, called “floss” in these newspaper articles, which were used for life preservers and aviation jackets.

Calgary Herald 29 Aug 1942		Norfolk Virginian-Pilot 18 Sep 1942
The Salt Lake Tribune 21 Jun 1942		The San Francisco Examiner 10 May 1942

The pointed end where the fluff was located is the business end of the seed. It is where the embryonic root (the radicle) will push out of the seed coat. A plant growth hormone (auxin) will align the radicle to the gravitational pull thus this early taproot will seek the ground and water. Likewise, auxins and exposure to light will extend the hypocotyl, eventually emerging from the seed coat as the young plant stem with the seed leaves (cotyledons).

Getting Ready: Seed sorting
Open your seed package and check out your population of seeds. Look for fat, thick, large seeds where you can see the outline of the embryo. These are the best candidates for producing viable plants.

Pollination for milkweed flowers is dependent on insects, thus it is not surprising that some of the seeds are not plump or large. This is because that ovule was not fertilized by pollen. These seeds are not viable and may be discarded.

Some seeds may be folded. This happens when the seed is drying. Don’t worry about flattening them out. However, if the seed is broken and the embryo exposed, it is no longer viable. Seed breakage is common in the mail. Discard any with broken seed coats. If only the outer wing is broken, then the seed should be okay.

A mature milkweed seed

Crinkled and small seeds

Non-viable seeds (trash)

Stratifying Your Seeds
When milkweed seeds are fully ripe and dry, the embryo goes into dormancy. If you are planning to store seed for a longer period of time, such as until the spring, store the seeds in your freezer. This is called dry stratification and works for some seeds. I store mine either in a zipper plastic bag with seed envelopes in them or transfer to recycled glass bottles with a secure lid.

Milkweed requires moist stratification. Like with peas, water “wakes up” the embryo which is then waiting for cooler temperatures. Unlike for peas, sometimes this process takes several months for milkweeds. My last batch I started in September and achieved widespread germination in April.

I’ve found that moist stratification can be successfully achieved in one of two ways: