Winter Sowing Seeds Outdoors

We recently received a comment from Anita Bowers from Chester County PA about a method called winter sowing. This is a method that would be helpful for those of us who don’t  have the space indoors to start seeds. The USDA Agricultural Library’s Glossary defines the Winter Sowing Method as “a propagation method used throughout the winter where temperate climate seeds are sown into protective vented containers and placed outdoors to foster a naturally timed, high percentage germination of climate tolerant seedlings.” This same winter sowing (WS) method can be used in early spring to give half-hardy annuals a good start.

One of the big benefits of being able to start your own seeds is of course financial. Compare the price of a pack of seeds and the number of seedlings it will generate to the cost of purchasing the same number of seedlings from a nursery and its easy to see why starting from seed is cost efficient. Additionally the benefits of the WS method are that you save space, and there is no need for warming mats or grow lights.

So, how does this method work? Seeds are planted in recycled containers and then placed outdoors. The seeds begin to germinate early in the spring and are ready to plant as soon as the ground thaws. There are many types of containers that you can use from a simple clear plastic milk jug to various take out containers and water bottles. Think creatively. The important factor is that the lid of the container must allow light to get into the planting medium. 

If you use milk jugs or water bottles you will need to cut the jug apart horizontally. You can leave it attached just under the handle. Or you can cut it all the way around and then cut some slits vertically at the bottom edge of the top half, so that it will expand to fit down over the bottom.

Next, punch drainage holes in the bottom of your container. You will also need several hole in the top of the container so that any air can pass through and the seeds/plants don’t get too much moisture.

Fill your container with at least 3-4″ of regular potting soil and then moisten it.  Plant annual and perennial seeds as required by their size, hardiness, germination requirements, etc. Be sure to label them. Allow enough room for the seedlings to sprout and grow. If you have partially cut a milk jug open you will need to tape the cut bits closed with duct tape or other strong tape. You don’t want your container to blow open. Place the seeded  containers in a safe spot in your yard where they will get sun and be undisturbed by pets or other animals.

You will need to  check your containers occasionally for too much condensation. Also water when sunny if needed. When spring arrives you can prop container lids open or put additional holes in the top so that too much moisture doesn’t collect.  When danger of frost has passed you can plant your seedlings right into the garden. There is no need to harden them off.

There are many plants that can be started using this method. Hardy annuals can handle some frost and some may require stratification to germinate. (The USDA defines stratification as ” the practice of placing seeds in moist media and specific temperature regimes in order to break seed dormancy and promote germination”.)

Bachelor Buttons, Poppies, Violas, Snapdragons, Calendula and Cleome are some common hardy annuals that germinate readily with the winter sowing method.

Half-hardy annuals can tolerate some chilly weather but may be damaged by frost. Marigolds, Love-in-a-Mist, Four O’Clocks, Cosmos, Petunias, and annual Salvias can be started by the WS method in early spring.

Tender annuals often wither at the least touch of frost. They can also be started in WS containers, but it’s best to wait until the time for hard freezes is past. You can also direct-sow tender annuals after the soil warms up., but the WS method gives them several weeks’ head start, as the container serves as a sort of miniature green house. Morning Glories, Nasturtiums, Zinnias, Basils, and even Tomatoes can be started this way, especially cherry or other early bearing varieties.

The WS method can also be used with perennials. Examples of what we might put in our butterfly garden are the Aster, Bee Balm, Blanket Flower, Blazing Star, Butterfly Weed, Coreopsis, False Indigo, Joe-pye weed, Ox-eye Daisy, and Coneflower.

Native plants that have been successfully WS in our zone are:

Aquilegia canadensis – Red columbine

Asclepias tuberosa – Butterflyweed

Baptisia australis – Blue wild indigo

Cornus canadensis – Bunchberry

Echinacea pallida – Pale purple coneflower

Filipendula rubra – Queen-of-the-prairie

Geranium maculatum – Cranesbill

Lilium canadense – Canadian lily

Lobelia cardinalis – Cardinal flower

Lupinus perennis – Wild Lupine

Mertensia virginica – Virginia bluebells

Mitchella repens – Patridgeberry

Monarda fistulosa – Oswego Tea

Podophyllum peltatum – Mayapple

Rudebeckia hirta – Black-eyed Susan

Sanguinaria canadensis – Bloodroot

Sassafras albidum – Sassafras

Trillium grandiflorum – White trillium

This list was taken from the Ganondagan web site. For more information click here. For another resource list of seeds that can be winter sown click here.

Remember that whatever you decide to plant using this method, you need to use seeds for plants that are appropriate for your area of the country and the conditions in your garden.

-For some videos on this method please click here or here.

Other references:

Madison County Master Gardener

How to Winter Sow

NOTE: Please let us know if you have already tried the WS method and what kind of results that you have had.


About chestercoextbutterfly

I am an apprentice Master Gardener with the Pennsylvania State University (PSU) Cooperative Extension Program. My local office is in Chester County. As part of my volunteer activity I am working with a team to develop a Butterfly Garden on the grounds of the  Church of the Loving Shepherd.  We will be using the creation of this garden as an educational program for some of the participants in the Bournelyf Special Camp which, is held every summer. Members of the congregation of the church will be involved as well as in the ongoing maintenance of the garden.The purpose of this blog is to document the project as it develops.
This entry was posted in Annuals, Native Plants, Perennials and tagged , . Bookmark the permalink.

4 Responses to Winter Sowing Seeds Outdoors

  1. Lee says:

    Great information, thanks.

  2. Anita Bower says:

    I’m delighted to read this post explaining winter sowing! It is such an easy and fun way to start seeds, whether purchased or gathered from one’s garden. It also provides gardening opportunities in the winter. Best to you in your work at creating a butterfly garden, which I know will be excellent as you understand the importance of larval hosts. 🙂

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