Labeled seed-starting containers surrounded by light snow and early sprouts.

Winter Sowing Native Plants

Planting Tips| Winter| Native Plant Gardens

February 03, 2025•10 min read

Winter Sowing:

Winter Sowing is simply the technique of planting seeds in containers at the beginning of or in the middle of winter and leaving them outside. Native Plants can be finicky little buggers when it comes to getting their seeds to germinate.

One of the biggest reasons for this is that most of them require a cold-moist stratification period to germinate. This basically means that they need to go through the various freeze-thaw cycles of a winter in order to break dormancy. Different species require different lengths of stratification periods, so if you've reached February and haven't started winter sowing, there are still some species that you can work with no problem.

Here we're going to discuss how to go about winter sowing as well as provide a list of native plants that can still be started outdoors. If you want to try winter sowing but don't have any seeds Wiggle Worm will have native seeds available for sale at the Mid-Winter Celebration and Seed Swap!

Read on to learn the general steps you'll need to follow:

Key Takeaways

Winter sowing mimics natural freeze-thaw cycles to germinate seeds.
Use containers with proper drainage and nutrient-poor soil mixes.
Protect seeds from critters and monitor them as they germinate in spring.

Pick your container.

Really, you can use just about anything that will hold soil provided it's deep enough to give your seedlings room to grow healthy roots until you either plant the in the garden or plant them up into a larger container.

Milk/Water jugs. The past few years have seen a rise in the popularity of milk jugs or water jugs as containers. The theory is that the top of the jug will act as protection as well as providing a little extra warmth in the spring for your seedlings to get going.

I have tried using old water jugs and I'm afraid they just aren't my favorite containers for seed starting. Because the tops stay on you have to make sure that the soil medium doesn't dry out, which can be difficult in the spring, especially here in the Eagle Valley where our shoulder season temps can swing from hot to freezing in no time. You also have to water them yourself, even when we get natural precipitation, again, because the tops keep everything covered.

On the plus side they do help keep your seeds from getting eaten by critters and because they're basically tiny little greenhouses you might just get seed germination earlier than with other methods. If you use these containers just make sure to keep an eye on them when the weather starts to warm up and bring them inside as soon as the seeds germinate to keep them from freezing.

Old plant containers. What gardener doesn't have a stack of plant containers hanging out at the back of the shed or garage just waiting to be used? Why not use them to start some seeds!? These are my favorite containers to use for Winter Sowing.

Generally, I'll stick to the smaller containers that can fit in a flat together easily but if all you have are gallon containers that's fine. If you use gallons, you might just have to do a little extra to set up a space where they're sure not to fall over during the winter.

Anything else that will hold some soil. I've even used old cracked ceramic baking dishes that I couldn't cook with anymore. Really, as long as it holds soil, and you don't mind leaving it out all winter you can use just about anything. If it's something that doesn't have any drainage, you'll just have to either add some drainage holes or keep an eye on it when the snow starts to melt to make sure it doesn't get too waterlogged. Also be prepared to have to transplant your seedlings sooner than you might have to if you use a container designed for plants.

Pick your soil.

I could, and probably will, do a whole blog on soil for native plants. The practice of growing native plants from seed is one that is still somewhat new for a lot of professionals, and as such there are a lot of opinions about soils and what works best for natives. In general, most of our native plants prefer nutrient poor, well-draining soil.

Commercial potting mix is a good place to start for winter sowing but try to find organic and peat-free options if you can. It can be tempting to go for the more expensive seed starting mixes, but these are mostly for indoor seed starting. They're main benefit is that they've been sterilized but if you're sowing outdoors in winter the cold provides some of that for you and the soil will be exposed to all the fun fungi and other naturally occurring microbes so paying for sterilization is a bit wasted.

If you want to cater more to what native plants really want you might consider adding one or more of the following amendments: sand, perlite (or vermiculite), pea gravel, or crusher fines. You can even add native soil if you have access to some, though you'll want to avoid heavy clay soils for seed starting. Also make sure that the area your collecting soil from hasn't been treated with any herbicides recently.

It often takes years of experimentation to find a mix that is perfect for you and your specific growing environment, but here are a couple of mix formulas you can start with:

Option 1:

1 part organic potting mix
1 part sand
1 part pea gravel

Option 2: the NARGS, from 'The Crevice Garden'

1 part coir (or peat if you can't find coir)
1 part perlite
1 part sand

Plant your seeds.

As a general rule you don't want to plant your native plant seeds very deep. For very small seeds, just spreading them on top of the soil and covering with a very light layer of sand is usually sufficient. For larger seeds, plant no more than twice the seed diameter, and cover lightly with sand or perlite.

Larger seeds may also need what is called 'Scarification' to increase their germination rates. This is basically the process of creating one or multiple small nicks in the seed coat that allow moisture to penetrate the tough outer coating. Often, the natural movements that occur as soil freezes and thaws are enough to scarify the seeds without you having to do it manually, especially if you've included sand and or gravel in your planting mix. (We will discuss Scarification in more detail when we post about starting native plant seeds indoors).

Because native plant seeds tend to have a lower germination rate than veggie seeds, it's fine to plant many seeds in one container, just make sure to keep your species separated. For those very small seeds, like Artemisia frigida (Fringed Sage), don't spend too much time trying to space seeds perfectly even. Just take a pinch of seed and spread them as best as you can.And finally, don't forget to label your containers! Many of us know that it can be sooooo easy to tell ourselves that we will remember, for all eternity, what we have planted in each container. And then we're inevitably left in the spring staring at a bunch of unidentified seedlings and cursing our past selves who really should've known better. It just takes a little bit of time, but it is infinitely worth it to make sure that you properly label every container with the species name and even the date planted.

Find a good spot to place your containers for the winter.

Usually, the best spot will be the north facing side of a building or fence. A north facing aspect will help keep any snow we get from melting thereby keeping your seeds under a nice protective layer for the season. If you can't place your containers in a spot where the snow will naturally stay on them for long periods, or if we have a season with abnormally little snowfall, you can shovel snow from walkways or the driveway onto your containers to keep them covered. The main thing is to keep them somewhat sheltered from wind and sun.

Protect your seeds!

One of the biggest threats to your seeds when your winter sowing are critters. If you're using an enclosed container, like a jug or plastic bag you won't have to worry about covering your containers. If you're using old plant containers or something else with an open top you'll need to keep out the voles, mice and birds with some kind of screen or mesh covering.

I have seen people use chicken wire but if you think about it, most of our rodents that are active in the winter are plenty small enough to get through your typical chicken wire mesh. So, find something that has small enough holes that most small rodents won't be able to work their way through it. I

f you try to use something like a permeable fabric to cover your containers, just be aware that unless properly supported, these can get pushed down by snow over the winter and then freeze to the soil in your containers. Then in the spring when things warm up there's a good chance that your small seeds will stay stuck to the frost cover rather than stay in the soil. So just make sure to build a sufficiently supportive structure to hold up the fabric.

Finally, once you've made it to spring and you're starting to see the green of seedlings sprouting, make sure to treat your seedlings like the babies they are. Keeping them watered is the most important thing. If they're full sun plants they'll also need a gradual introduction to full sun conditions.

Just like any baby, you don't want to just huck them out into twelve hours of direct sunlight right away. They need to be hardened off. Native plants can be very resilient, but they still need a little tender care when they're young.

At some point, you're going to have to either transplant your seedlings directly into the garden or plant them up into larger containers, but we'll discuss all that in a later post about planting techniques.