Native Plant Winter Sowing FAQs
Updated: Feb 2, 2022
Winter sowing is so popular and timely that I’ve received a number of questions since my post on the topic. Hopefully by answering the following questions I can make winter sowing more accessible. I’ll try not to repeat the basic information I shared in the last post. For this reason, it might be best to read it before reading this because it was about how to use foil roasting pans instead of clear milk jugs.
Winter Sowing FAQs
Can I winter sow spinach, snapdragons or sage? The only seeds I’ve winter sown are native plants and I’m sharing my experiences doing this. Most online resources for winter sowing are geared towards traditional gardening, not native plants and will give you detailed information about propagating vegetables, non-native flowers, and herbs. There is a popular Facebook group called Winter Sowing (Vegetable Gardening). I like your idea of using foil roasting pans, but where else can I learn more about winter sowing native plants? The best resources seem to be environmental education sites because they often focus on winter sowing native plants, but general winter sowing information will also apply to native plants. Trudy Davidoff who coined the term winter sowing was a great primary source but the site is no longer active. Other basic resources include the Wild Seed Project, Ecological Landcape Alliance, and Joe Gardener.
What seed planting medium do you use? Surprisingly, one of the most confusing and debatable issues for winter sowing seems to be about what medium to use. The simple answer is I use whatever organic, natural potting soil I can find at the local nursery and add a half inch layer of seed starting medium on top. The more complicated answer: Garden soil and homemade compost will become too dense for seeds and there’s controversy over the sustainability of peat. Both perlite and vermiculite are not clear choices for similar reasons. After weighing my options, I decided to use higher quality brands such as Black Gold which have organic potting soil and seedling mix options; although I’ll use any brand I can find that is organic and natural and doesn't have artificial fertilizer or water retention additives. I can justify a mix with a relatively small amount of peat because I don't use peat anywhere else when gardening.
Foil Roasting Pans
I don’t live in Georgia. Will using foil roasting pans instead of plastic jugs for winter sowing work for me? I write about what works and doesn’t in Atlanta which is in the Georgia Piedmont growing region. I’m not sure about other regions so you might want to check with your local native plant resources to see if my suggestions work where you live.
Where do I buy foil roasting pans? My local grocery store carries the heavy-duty foil roasting pans with clear dome lids. They can also be bought in bulk online.
Does it matter what size I get? Get the largest and deepest pans you can find. Don’t use shallow pans because they won’t provide enough support for seedling roots and will dry out quickly.
Can I use the pans I already have even though they don’t have clear dome lids? The clear dome lids create the mini greenhouse effect necessary for successful winter sowing. I’m not sure how to use the pans without these lids for winter sowing. There might be an online resource for just the lids, but I haven’t explored this option.
How much do the roasting pans cost? The pans are about $4-5 each but are often on sale.
Can the pans be reused? I’ve reused mine for two years and I’m hoping I’ll get at least one more year out of them. The plastic tops sometimes break a bit but can be patched with slivers of duct tape.
Drainage and Ventilation Holes
How many slashes do I make in the roasting pans before adding soil? There’s no right number, but I make about 16 slashes in the roasting pan which seems to be enough for drainage. For drainage, make the slashes from inside the foil bottom for better drainage.
How exactly do I poke holes in the plastic domes and how many holes are needed? My quirky method initially involved heating up old barbecue skewers or screwdrivers over gas burners then going to the back porch to poke holes outside and repeating, but it turns out a small soldering iron works even better. I've also been told a hot glue gun without glue sticks in it also works. In general, the thinner the holes the more holes you'll need. Make sure to do this in a ventilated space or preferably outside. I just can’t figure out a less toxic way to do it or I would! If you try to poke or cut holes without heating up something metal, you’ll crack the plastic. Someone told me they tightly stacked the plastic tops and slashed them with a stained glass lead came knife but I haven't tried this yet.
Since mother nature will take care of the seeds, do I still need to water them before setting outside? Yes! The seeds need to be watered before being set outside. Once outside, they’re fine on their own and won’t need any attention until the seedlings start growing.
Does it matter how many dividers I use in the roasting pan? The great thing about using a large roasting pan is it can be divided in several ways depending on the quantity and variety of seeds you want to plant.
Why don't you use cardboard divider strips? What do you use instead? Last year I used cut up cardboard for dividers because it's non-toxic and biodegradable. I just used boxes from the daily deliveries to my house. Cutting the strips was easy with a utility knife. When the weather started warming up the strips of cardboard starting decomposing and molding a bit which wasn't great for the little seedlings. The cut up yards signs I used as an experiment seemed to hold up better and could be washed and reused, so that's what I'm using going forward.
Wow, those seeds are thickly sown. How do you pinch out the ones you don’t want? Winter sowing native seeds is much different when it comes to how thickly you can sow the seeds. Once they’re transplanted, a survival of the fittest battle takes place the same way it would if a bird ate a bunch of seeds or seed pods fell to the ground during the winter.
Once they're winter sown, is there anything else I have to do besides leaving the pans outside in the shade? Nope! I’m not a botanist and the process of cold stratifying in the refrigerator requires too much on-task attention for me. Winter sowing is popular because it lets mother nature do most of the heavy lifting. When the seedlings start sprouting you will need to jump back in and help though. I’ll revisit this topic again in the spring and explain what to do then.