Last updated on October 22nd, 2023 at 09:01 pm
Planting milkweed seeds in winter is a great project for the pollinator garden. Winter is the ideal time to plant these Monarch attracting plants, allowing time for stratification and germination of the seeds.
What Is The Best Time To Plant Milkweed Seeds?
If you have just ordered some milkweed seeds for your garden, and wondering when they should be planted, planting milkweed seeds in winter is just what you will be wanting to do.
Milkweed seeds can be planted in winter, after a period of seed stratification. Milkweed seeds can also be planted in the ground in fall, to allow for a natural process of stratification outside in winter.
This stratification process is for types of milkweed growing in northern climates that have a harder seed shell, such as the Common milkweed, or Swamp milkweed.
What is stratification?
- Stratification is the process by which the cold hardy seed coat gradually breaks down and softens enough to allow the initiation of the germination process.
- This tough outer seed coat protects the seed throughout the winter.
- By the time the warm weather of spring has arrived, the seed is ready to sprout and grow into a new seedling.
How Do You Germinate Common Milkweed Seeds?
If you are going to be planting milkweed seeds in winter, you should use a technique that will help to stratify the milkweed seeds, so that they will sprout for you.
How To Cold Stratify Milkweed Seeds
This is easily done in several ways.
- The first method is to give the seeds a damp chill in your fridge. This period of damp chilling replicates the natural process the seed would experience outside in winter.
- The second method is to winter sow the seeds, planting them in a winter sowing container and placing them outside to naturally experience the freezing and thawing temperatures which will aide in germination.
Using The Damp Chill Method To Germinate Milkweed Seeds:
The damp chill method involves chilling with dampness, in the fridge. This can be achieved several ways.
- The first way is to place the seeds in a moist paper towel, which is folded over to cover the seeds. Make sure the paper towel is not dripping wet, just damp enough to provide a bit of moisture.
- Place the moist paper towel with the seeds into a plastic baggie, and put in the fridge for a one month chill, if possible.
- Another way to provide the damp chill is similar to the first. You can use moistened vermiculite instead of paper towel. Place the vermiculite in a plastic baggie, and place the seeds inside. This is the process that I used this winter.
- Chill the moistened vermiculite and seeds in the fridge for about one month.
After a month in the fridge the seed coats of the milkweed seeds became very soft to touch, demonstrating the positive effect of this process on the outer seed coats.
Can You Winter Sow Milkweed Seeds?
Milkweed seeds can be winter sown, starting anytime that you would normally sow your seeds using this technique.
We winter sow our seeds in February and March here in zone 5b. We often have snow until April, with lots of freezing and thaws.
For a full description on how to winter sow, you can read this blog post on Winter Sowing In Milk Jugs, Cold Stratification.
When To Plant Milkweed Seeds
If you are planting milkweed seeds in the fall by direct seeding, wait until late in the season to place the seeds into the garden. They will remain dormant throughout the winter.
The natural stratification process of winter will break down the seed coats and the seeds will be ready to germinate in spring.
If you are planting the seeds in winter, put them through the stratification process in your fridge.
After the stratification period, the seeds can be planted into a good quality seed starting mix.
Milkweed seeds produce a long taproot, and this should be a consideration when choosing your planting container. Disturbing or damaging this taproot can have a negative effect on your seedling.
Choosing a container that can be directly planted into the garden, such as a peat or paper pot can be helpful.
How Long Does It Take Milkweed Seeds To Germinate?
- Germination should occur within several weeks.
- We planted two types of milkweed seeds this winter, Common Milkweed (Asclepias syriaca) and Swamp Milkweed (Asclepias incarnata). We purchased our seeds from Annapolis Seeds here in Nova Scotia.
- For both types of milkweed seeds that we planted, we did both the winter sowing technique, as well as planting inside under lights. Our seeds were moist chilled for one month in the fridge.
- We planted our inside seeds in seedling trays, and we will be very cautious of the tap roots of the plants.
- The new milkweed seedlings will require warmth and light as they grow throughout the winter months.
- Grow under grow lights if possible, and bottom water for best results.
Our milkweed seeds germinated within a week of planting.They have been growing nicely under grow lights.
Here are some photos of the seedlings at 2.5 weeks from planting the seeds:
Transplanting Milkweed Seeds Into the Garden
Transplant the young seedlings into the garden after the danger of all frost has passed.
Milkweed seedlings are vulnerable to transplant shock, so they shouldn’t grow too large before transplanting into the garden.
Plant in an area with full sun, and provide lots of moisture.
Planting A Garden For Monarchs and Other Butterflies
Consider planting a garden for Monarchs and other butterflies.
Through the years we have had a few Monarchs come visit, and have seen many Black Swallowtail butterflies at the farm.
This past summer I discovered this sweet little Black Swallowtail butterfly caterpillar on our Ammi.
With our new milkweed plantings we are hoping to have many more Monarch visitors in the garden!
Does Common Milkweed Bloom The First Year?
- During the first summer the small young milkweed seedlings will put their energy into growing a good root system, and you will not see any blooms.
- The second year milkweed plants will have substantially larger plant growth. However are still not mature enough to bloom. Monarchs will still be attracted to the plants and may feed on the foliage.
- Milkweed blooms are produced in the third year of growth, and will attract Monarchs to your garden.
Consider Planting A Habitat For The Monarch Butterfly And Other Pollinators.
It is a wonderful experience planting pollinator attracting plants. Watching these special pollinators all around you, enjoying the plants that you grew for them can be very rewarding!
If you have any questions or comments on planting milkweed in winter, please leave a comment below!