Milkweed Germination

We have germination! If you are curious to how we got here, check out my two previous posts, sowing seeds in perlite and sowing milkweed seeds, which will help explain how we got the milkweed seeds to germinate.

Asclepias lanceolata seedlings

Like babies, young seedlings are fragile and defenseless, but have an instinctive incentive to stay alive and grow. Fortunately, unlike babies, seedlings don’t need food at this early stage of growth and have just two basic requirements: light and water.

After the seeds germinate, I like to move them outside to an area with filter light and keep them in the plastic bag that they germinated in. Keeping them in the plastic bag maintains a humid microclimate and prevents premature drying out, animal disturbance, and damage from heavy rain or hail. Be careful not to leave the seedlings in direct sun while they are still in a sealed plastic bag, as it will act like an oven and cook them.

Over the next week I gradually open the bag to acclimatize the seedlings and, weather permitting, they are out of the bag and in morning sun with some afternoon shade. The seedlings can tolerate moderate frosts (if acclimatized), though I usually protect them if the temperature is going to drop below 30°F.

While the seedlings are in the plastic bag they probably don’t need watering, as they were soaked after the seeds were sown. Once out of the plastic bag, I have found that the best way to check for watering is to lift the container and check its weight. This is where the beauty of perlite as a seed germination medium comes into play. Because perlite drains so well, you can use the motto, “when in doubt, water.” The exception to this rule is milkweeds that prefer drier conditions, like Asclepias amplexicaulis and Asclepias humistrata. I try to let these milkweed seedlings dry out a little between waterings. I use a watering can with a fine rose to water, but you can also soak the container in a dish of water for 5 to 10 minutes and achieve the same result.

watering milkweed seedlings with a watering can

Don’t be in too much of a rush to start fertilizing. I can’t recall killing a single plant from using too little fertilizer, but I’ve killed my fair share of plants from getting too eager and fertilizing too soon or using too much. Once their true leaves emerge (the first leaves are called cotyledons and have stored food in them), start using a liquid feed at 1/4 of the recommended mixing instructions on the label.


  • Protect young seedlings from drying out, animals, and extreme weather
  • Supply filtered light while seedlings are still in sealed plastic bag
  • Gradually move seedlings out of plastic bag and into more sun
  • Check regularly for watering and if in doubt, water
  • Don’t over fertilize seedlings

In the next and final post on seed germination, I’ll show you how to transplant your milkweed seedlings into individual containers.


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