Winter Sowing Milkweed Seeds Part 1: Supply Checklist

Winter Sowing Milkweed Seeds for Monarch Butterflies: What supplies will you need and what household items can you use for containers?
Winter Sowing Containers | Photo by Cristina

Each year I try to implement new gardening techniques that get more results with less work. This year I’m adding winter sowing to that list. Is winter sowing right for you?

3 Big Advantages to Winter Sowing Milkweed

Almost everyone in North American can benefit from winter sowing milkweed seeds. The few exceptions are those that live in regions without a true winter.

1. Winter weather provides a natural cold stratification process. When seeds are subjected to cold before gradual warmth, this breaks their dormancy and causes them to sprout. Warm weather varieties (e.g. tropical milkweed) don’t require this.

All of the species listed here do require cold stratification, which makes them good candidates for winter sowing. Each link below will take you to a plant page or order page. You will be able to purchase milkweed seeds from both.

2. Seedlings sprout early inside their miniature greenhouses giving you a head start on garden season and north-migrating monarch butterflies.

3. You have more control of where plants grow. If you direct sow in fall or spring, seeds can get moved around by weather or wildlife before they germinate.

When to Wintersow

Some start sowing as early as the winter solstice (which was just before Christmas). Earlier start dates are recommended for those further south, since freezing temps are in shorter supply.

I’ve started milkweed seeds inside before with less than one month of ‘refrigerator’ cold stratification. Starting seeds by February should be more than enough time to create the desired outcome.

Milkweed Varieties

Native milkweed is the cornerstone of a successful butterfly garden, so start with those species if you are just getting started. Once you have natives established, consider other non-invasive varieties to attract even more butterflies.

What’s native to your region?  Check out my milkweed resources pages, which lists the native region for 25+ milkweed varieties.

Common Milkweed Varieties that are Wintersown

Which Milkweed Varieties are prime candidates for winter sowing milkweed seeds?
A Winter Sown Success

1. Asclepias incarnata (swamp milkweed)

2. Asclepias purpurascens (purple milkweed)

3. Asclepias syriaca (common milkweed)

4. Asclepias tuberosa (butterfly weed)


6. Asclepias sullivantii (prairie milkweed)

We already have many native varieties established in our landscape, so our sowing choices are a little more adventurous, and won’t be a sure thing in our cold climate. When starting out, we focused on native and perennial options to insure our garden could always support monarch life.

So what’s new in our winter sowing containers?

New Milkweed Varieties for Monarch Butterfly Garden

Why Plant Uncommon Milkweed Varieties for Winter Sowing? You never know what's possible until your try. Of these varieties, I found Asclepias virids had a high germination rate after an extremely wet and cold Minnesota winter. That's not what I had expected...and nothing I could have learned from reading a book!
Thinking Outside of Your Zone

1. Asclepias variegata (redring milkweed) native to most of the eastern US and Canada. Suited for hardiness zones 3a-9b. (still haven’t found viable seeds for this species, but it’s on my list!)

2.native to much of the eastern US. An early milkweed for USDA zones 5-9. Surprisingly, we had excellent germination rates winter sowing viridis during the 10th coldest Minnesota winter on record…which was followed by a cold spring with torrential rains!

We also fall planted milkweed seeds in late October…why put all your seeds in one basket?

Make sure all winter sown milkweed species require cold stratification. Winter sowing warm weather milkweeds including tropical, swan, and giant could kill your seeds.

Winter sowing milkweed doesn’t require a huge investment (of your time or money!) and the rewards can be quite substantial when spring rolls around. You’ll be happy to learn most of the tools needed are already inside your home.

Winter Sowing Containers

10 Winter Sowing Container Ideas featuring convenient household items...
What Winter Sowing Containers Do You Already Own?

These are some container options that have been successfully used by other gardeners. Consider trying a couple methods to see if one works better for you. Keep in mind all containers must also be clear enough to allow light to penetrate the soil.

Any container should have the ability to hold up to 4″ of soil, with ample room up top for seedling growth.

Over the past two cold, wet springs (in Minnesota) we have had problems with M&Ms…mold and moss! This has only been in an issue in the opaque milk jugs that receive less light. We’ll still use opaque milk jugs, but will add more drainage holes growing forward.

Here are some containers to consider for your winter sowing milkweed adventures:

1. Disposable food storage containers with snap-on lids

2. Plastic Milk Jugs

3. 1L or 2L plastic soda bottles (we have had the most success using these containers)

4. Clear plastic storage bins with snap on lids (The lids don’t have to be clear)

5. Clear plastic Cups

6. Ice cream buckets

7. Grocery store Rotisserie Chicken container

8. Containers for baked goods like cakes, muffins, and cookies

9. Distilled water jugs

10. Plastic fruit containers (eg strawberries or blueberries)


Potting Soil

Use a good all-purpose potting soil. Do not use a moisture-control variety, because excess moisture could lower germination rates for some milkweed species.

We use pro-mix which has sphagnum peat moss and perlite mixed in to allow more air around developing plant roots and improve drainage.


Other Tools Needed?

Duct tape, a scissors or box cutter, a marker for outdoor use, sturdy plant labels, and a drill (or something that will make drainage holes in your plastic containers).

Buy Plant Labels


Next Steps

Once you’ve got the necessary tools, it’s time to sow your seeds! Click the link below for step-by-step winter sowing instructions:

11 Simple Steps for Winter Sowing Milkweed

Please comment below with any questions about winter sowing tools…

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  1. Matt Baumann says


    Interesting info here!

    Quick question about planting of milkweed seed. I have read some information from other sources that say that milkweed seeds need light for germination and therefore should not be covered with soil when planted. Can you comment on this?

    Here in Iowa, I will be working to establish Sullivant’s milkweed, Butterflyweed, and swamp milkweed.

    • says

      Hi Matt,

      the 3 milkweed species you are growing require cold stratification. You can do this naturally with winter sowing or place seeds in the refrigerator in late winter and spring. I plant seeds about 1/4″ deep and cover with soil. You should have good germination rates this way, provided you have viable seeds.

  2. Brian says

    Hi Tony,

    This is the first year that I have collected warm weather milkweed seeds (tropical and goose/balloon). I have read that the refrigerator is generally the best place to store seeds as long as you keep your seed storage containers away from the freezer section of your refrigerator.

    I was wondering, how do you store your warm weather milkweed seeds over winter?

  3. Zack Bond says

    Hi Tony,

    I started a butterfly garden a few years ago and this past summer collected all my milkweed pods to donate and give to friends to help promote native host plants for Monarchs.

    My concer however is that I gathered all the pods at the summers end and they’ve been on a shelf in the house since. They seem very try and brittle now. Does mean they will be no good now for winter sowing and harvesting?

    Any feedback would be appreciated!

    Thank you!


    • says

      Hi Zack, is it possible you picked the pods before the seeds were ripe? We typically separate all our seeds when we harvest them and store them in paper or plastic bags once they are fully dry.

      It can’t hurt to try winter sowing, but make sure you have an alternative source for seeds or plants if things don’t work out…good luck!

  4. Bridget says

    Question: I’ve brought several milkweed pods from NH to Long Island NY. Can you provide info to help them survive in this different climate zone please? Thanks!

    • says

      Hi Bridget, I wouldn’t worry too much about transporting seeds from one location to another. I would focus on whether the species is perennial to your region, which I’m guessing it is since NY and NH are both out east. You can winter sow the seeds or try fall planting. Here’s more info:

      Fall Planting Milkweed Seeds

  5. jackie says

    Hi Tony, I have had a surprising experience. Here in southern Louisiana we have not had a cold winter. The few times we have had a freeze I have covered up my milkweed trying to save it for the coming year. It is growing fine and blooming too. Well yesterday I go out to check the plants in the garage and to start planting my seeds for the winter in my trays when I all of a sudden I see a cat!
    I also had to cover the plants outside for a freeze last night. Well I searched all the milkweed in the yard…I have 9 cats!

    My questions are 1) I have enough milkweed to get them through but what about the butterflies? I don’t have any flowers. 2.) Are these still the super butterflies that live 6 months? Can they still make it to Mexico? They are roughly about two weeks old now.

    I have gathered them together and have them inside now to keep them warm.
    I would appreciate if you could give me some advice on this surprising event. Thank you Jackie

    • says

      Hi Jackie, what an unexpected January surprise!

      I don’t think butterflies will migrate this late in the season, but who knows? They could possibly survive winter in your region if you temps remain on the mild side…if they stay, they will probably live out a shorter life span like summer monarchs. It is possible they could mate with returning migrators.

      If they eclose during a cold spell, you may have to keep them a few days. In that case you would need to feed them. There is some info on this post about feeding/releasing adult butterflies. Good luck with your first batch of the new year!

      Release Monarch Butterflies

  6. brian wendel says

    I’ve got my milkweed seeds stratifying in slightly moist sand to plant soon. Wherever did you get the redring milkweed seeds as the plant is supposedly ever so rare? Ready for super sow Sunday but it might be on Monday that they get planted.

    • says

      Hi Brian, I had gotten them from a gardener a while back and the seeds weren’t viable. Every once in a while, I’ll search for seeds online but no luck. One of these years, hopefully…good luck with your winter sowing containers!

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