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 18+ 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.

3. Asclepias syriaca (common milkweed)

4. Asclepias tuberosa (butterfly weed)

5.

6.

We already have many native varieties in our landscape, so our sowing choices are a little more adventurous, and won’t be a sure thing in our cold climate. By next spring, we could have 15 species of milkweed in our suburban butterfly garden, if all goes well.

So what’s cooking in our 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.this western native only grows to 1′ tall, and produces fragrant flowers in late spring. Suggested for USDA hardiness zones 5-10.

2. Asclepias hallii (hall’s milkweed) a second western milkweed that’s recommended for hardiness zones 5a-9a.

3.a California native that trails along the ground. Best suited for hardiness zones 7-9.

4. Asclepias variegata (redring milkweed) native to most of the eastern US and Canada. Suited for hardiness zones 3a-9b.

5.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.

The containers we’re considering are in bold lettering:

1. Disposable food storage containers with snap-on lids

2. Plastic Milk Jugs

3. 1L or 2L plastic soda bottles 

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.

Other Tools Needed?

Duct tape, a scissors or box cutter, a marker for outdoor use, 6″ plant labels, and a drill (or something that will make drainage holes in your plastic containers).



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…

Comments

  1. Matt Baumann says

    Hello,

    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!

    Zack

    • 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!

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