Winter Sow Native Plants

Why winter sowing is the best way to start your native seeds

Some of the most nostalgic memories from my childhood are from the moments I was able to run freely through meadows and—with magnifying glass in hand—across boardwalks at the bog. I still vividly remember the sound of the low hum of the pollinators, the radiance of the sun on my shoulders, the warm and comforting smells that greeted me at every turn, and the familiar sight of native plants growing wild and free.

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Native plants are the species of plants that have co-evolved with the ecosystem of a particular area. Because of this, native plants, insects, and wildlife are profoundly reliant on one another. Aside from the beauty and joy that comes from growing your own native plants, they also provide many benefits:

• Native plants provide essential food and shelter for pollinators, beneficial insects, birds, and other wildlife

• Native plants keep the air clean and improve water quality

• Native plants help repair and sustain healthy soil

• Native plants out-compete invasive species

By growing native plants, not only will you be adding beautiful low maintenance plants to your garden, but you will also have an impact on sustaining the ecosystem surrounding you.

Understanding native plant seeds

In order to survive the elements and periodic climate conditions that aren’t suitable for sustaining the life of a native plant, many native plant seeds have innate mechanisms for remaining dormant until growing conditions are right. While this built-in mechanism is absolutely vital to the sustainability of native plants, it can make the process of starting them from seed feel a bit daunting to the home gardener

Breaking dormancy

So you might be asking, what are these built-in dormancy mechanisms, and what is required in order to break this dormancy?

Many native plant seeds have layers of hard coating that prevent the seed from germinating unless it has gone through a cold moist period. This cold period, followed by a freeze-thaw cycle is what breaks down the seed coat and allows water to then enter the seed in order to begin the process of of germination.

Cold stratification is the process of exposing these seeds to the conditions they need in order to bring about germination. Many gardeners use artificial cold stratification to simulate what happens in nature. While this can be highly effective, some find this process to be a bit tedious and high maintenance. Winter sowing provides a better way—nature’s way!

Winter sowing: the best way to grow your native plants

Winter sowing is an easy and economical seed starting method. In this method, plastic containers (like milk jugs) are used to create mini greenhouses for seeds to germinate and grow outside before the last frost date.

When used at the proper time, the winter sowing method essentially models the same pattern seeds take in nature. That is, scattered on the ground—then entering a state of dormancy with cold temperatures, followed by a freeze-thaw cycle. When conditions are right, germination occurs and seeds develop into robust seedlings that are already acclimated to the outside elements.

The most important thing to take into account when using this method for growing native plants is how many days of cold stratification are needed for the plant you intend to grow. Your native plant seeds will need to be winter sown within a time frame long enough to expose them to cold for the length of days required specific to that seed. I like to winter sow my natives around winter solstice—as this provides my native seeds the largest window of opportunity for cold stratification to occur. When the time is right, seeds sown this way will effectively break dormancy with very high germination rates.

The reason winter sowing your native seeds results in such high germination rates is because not only does this method mimic the process that occurs in nature, but there is also an added element of protection both before and after germination has occurred.

Avoiding harmful cultivars

Not all plants labeled “native” are true to their wild type— these are sometimes referred to as cultivars. Often, cultivars are nursery bred and the appeal is garden aesthetics. Cultivars lack genetic diversity that is vital for adapting to region specific environmental conditions. Because of this, cultivars often don’t thrive as well as their wild type, and cross breeding may also occur. Cross breeding of native species with cultivars (resulting in hybrids) opens up the threat of extinction to their wild type and poses an even greater threat to our ecosystem at large. Growing natives that are true to their wild type offers the most benefit to the home garden and preserves our ecosystem.

So how do we avoid these cultivars? Use botanical names, and buy from reputable sources.

Sourcing seeds

So much of what I’ve learned about native plants of North America has come through the education and resources provided by Prairie Moon Nursery. As one of the leading sources for education on native plants of North America, Prairie Moon Nursery is a great place to source native seeds. They offer seeds for over 700 species in their wild type and have made growing information incredibly accessible to the home gardener.

Their website has a very user friendly filter engine that can help you find exactly what will thrive in your garden. They even have a filter based on cold stratification requirements which is why they are my go-to for winter sowing!

Scroll down to see a list of some of my favorites!

Where to start

A simple rule for understanding which native plants will do best when using the winter sowing method is this: if the plant species is native to your state—in other words, if it’s origin is local and therefore grows naturally in your area—it can be winter sown.

Native plants grow best and provide the most benefits when they are grown in the specific areas they were first established. Below are some great candidates for winter sowing categorized by their native range.

Filtering your search using your state will give you even more to choose from! This list is made up of seeds that only require 10-30 days of cold stratification—making them a great option if you’ve already missed the larger windows for cold stratification.

Midwest

• Anise Hyssop - Agastache foeniculum

• Blue Wild Indigo - Baptisia australis

• Black-eyed Susan - Rudbeckia hirta

• Joe Pye Weed - Eutrochium maculatum

Northeast

• Common Milkweed - Asclepias syriaca

• Blue Wild Indigo - Baptisia australis

• Black-eyed Susan - Rudbeckia hirta

• Brown-eyed Susan - Rudbeckia triloba

South

• Rose Milkweed - Asclepias incarnata

• Sundial Lupine - Lupinus perennis subsp. perennis

• Yellow coneflower - Ratibida pinnata

Great Plains

• Blue Vervain - Verbena hastata

• False Indigo - Amorpha fruticosa

• Lead Plant - Amorpha canescens

• Rose Milkweed - Asclepias incarnata

West

• Showy Milkweed - Asclepias speciosa

• Black-eyed Susan - Rudbeckia hirta

• Blue Vervain - Verbena hastata

• Large-Flowered Water Plantain - Alisma triviale

  

Winter Sowing Native Plants FAQ

Can I winter sow any native plant of North America?

Native plants specific to your state will be the easiest to grow and provide the most benefit to your garden. But any North American native plant can be grown provided it has the right conditions. If you do choose a plant from outside your range, you may need to use artificial means for cold stratification.

Some native plants require a full year of exposure to warm/moist and cold/moist periods. I have not personally attempted to winter sow seeds of this kind but know others who have, and had unsuccessful germination.

When should I winter sow seeds for my native plants?

Native plant seeds come in a wide range of germination requirements. Some need several months of sustained near-freezing temperatures while others might only require around a week of cold temperatures. The key to successfully winter sowing native plant seeds is starting them at a point where you know there will be more than enough time for them to be exposed to the length of days required in the cold.

The best thing you can do to know when to winter sow your native seeds is to learn the germination requirements for the specific plant you are growing. As a best practice and for a low maintenance approach, I winter sow all of my natives around winter solstice — this way I know they’ll get what they need.

It’s almost March and I’m not sure if I’ll have enough time to winter sow my seeds that need 30 days of cold stratification. Can I artificially cold stratify my seeds and then sow them in jugs?

Yes! Here you can find helpful resources for artificial cold stratification.

Are you convinced?

Will you be growing native plants this year? Will you winter sow them? I’d love to hear which species you have grown in the past and which ones you are winter sowing this year!