Native Plant Seeds are Ideal for Winter Sowing

OR Tips for Winter Sowing Native Plant Seeds Using Foil Roasting Pans With Lids. Winter sowing is a way to germinate seeds by mimicking the way they would grow in nature. By sowing seeds outside in ventilated containers, the germination rate is increased and the seeds are protected from disappearing in the garden or being eaten by any number of hungry critters. This method is designed for seeds that need the cold and moist cycle of winter conditions (stratification) before they can break dormancy and sprout when nature tells them to.

I prefer to winter sow in foil roasting pans instead of the more popular plastic jugs.

In the 20 years since Trudi Davidoff first coined the term, winter sowing has become wildly popular in gardening circles because it's not as fussy as growing seeds inside. It turns out winter sowing is a particularly ideal way to germinate native plants because they are growing in the regions where they would naturally exist; unlike non-native plants that would prefer to grow in the far away climates where they are from.

This year I'm winter sowing very small quantities of over 100 native plant seeds.

I now winter sow all my native seeds, including the warm season ones. They stay dormant in the winter and seem to know exactly when to sprout as the days get longer and the weather warms up. There are many great resources for how to winter sow. The main requirement is the containers be about 3-4 inches tall with drainage holes and a clear top with ventilation holes.

I've tried many different containers to see which ones work best for winter sowing in Atlanta.

The most popular way to winter sow is using clear plastic milk jugs cut in half with holes poked in the bottom for drainage. The seeds are sown in the bottom half and duct tape secures the top. Preparing the jugs took me a long time because the plastic was thick and difficult for me to cut because I have weak hand strength. Storing and reusing the jugs so the tops and bottoms matched up was kind of a pain. I tried multiple containers for comparison and had a 85-90% germination rate with the foil roasting pan and a 60-70% germination rate with the plastic jugs. The roasting pan became my preferred method!

These are the foil roasting pans with lids I use for winter sowing. They're 2 7/8 inches tall which is just about the 3 inches suggested to give the seedling plenty of room to spread their roots. I buy them around the holidays when they are typically on sale. I sometimes am lucky enough to find them on clearance after the holidays! They can also be found in bulk online.

It's easy to quickly cut slits in the foil pans with a utility knife for drainage and poke holes in the plastic lids with a heated metal barbeque skewer, a small soldering iron, or a hot glue gun (without glue sticks in it) for ventilation. It's best to make the holes in the plastic outside because of the fumes. Someone also suggested stacking the plastic tops tightly and using stained glass lead came cutting knife to make slits in the baking pan plastic tops but I haven't tried this yet. The pans can easily be reused each year. Small sections of the plastic sometimes break and I just cover them with a little sliver of duct tape. As an added benefit, I can divide the pans to create more biodiversity by planting many varieties of native plants.

Baking pans with lids make perfect winter sowing containers because they can easily be divided to sow multiple varieties of seeds. I cut up yard signs to make the dividers. I tried biodegradable cardboard and it unfortunately broke down a bit too quickly and caused mold in the container when warm spring days returned.

It's easy to divide the pans to plant multiple varieties of seeds using cut up yard signs. Ask neighbors if you don't have any - everyone seems to have some in their garage!

I somehow invariably get the plastic and wooden stick labels mixed up by the time I need to transplant the seedlings, particularly when multiple varieties are in the same container. The game changer for me was using waterproof labels on the container itself. I can print out the common and botanical name as well as growing conditions which makes it easier when transplanting. If you plant the same seeds each year, the labels don't fall off or fade.

Waterproof labels ensure I don't mix up all the different native plants I winter sow

For soil I fill the pan almost to the top with potting soil then add a thin layer of seed starting medium. I mix the seeds with coarse sand so they'll be more evenly distributed on. The list of what mediums not to use for winter sowing includes compost, garden soil, and mixes with fertilizers or moisture control added.

Native seeds can be sown a bit thick because this is the way they would naturally grow. Cover each seed according to the directions since some seeds don't even need to be covered. Sand is the best cover for the seeds but I often use the soil I'm planting the seeds in and it seems to work just fine. The general rule is cover to the depth of the thickness of the seed meaning tiny seeds barely need to be covered.

Native seeds like these carex and grass seeds can be sown a bit thick and cut up and transplanted in chunks. These seeds are ready for their soil blanket!

Cover the container with plastic and seal it with small pieces of duct tape at the corners and in the center of each side then set outside in a shady location.

When winter sowing, little "greenhouses" are created by using foil baking pans with holes made in the top and bottom. You can see the small pieces of duct tape in the corners and middle of the trays.

Once you put the containers outside, there’s nothing else to do until spring. The hardest and most exciting part of winter sowing is just waiting until little green seedlings pop up!

The best part of winter sowing is watching all the baby seedlings pop up in the spring!