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.
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 is 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 (in most regions) to create the desired outcome.
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
These are the native and perennial milkweed species we planted to build our foundation…
Less Reliable Milkweed for a Northern Butterfly Garden
Once those varieties were established, our sowing options became more adventurous…
1. Asclepias variegata (redring milkweed) native to most of the eastern US and Canada. Suited for hardiness zones 3a-9b. (this has been reported to have a better germination rate using water stratification)
2. Asclepias viridis (spider milkweed) 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! Three years later, it keeps coming back…
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
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.
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)
We use pro-mix which has sphagnum peat moss and perlite mixed in to allow more air around developing plant roots and improve drainage. We are also experimenting with the seed starting mixes.
Other Tools Needed to Winter Sow Seeds?
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).
Once you’ve got the necessary tools to start seeds indoors, it’s time to sow your seeds of monarch love and move them outside! Click the link below for step-by-step winter sowing instructions:
Please see comment section below for more info about winter sowing tools…