If you have a vegetable garden every year, chances are you have started some seeds inside to get a head start on the growing season. Starting seeds inside can be messy. In addition, getting adequate light to the seedlings can be problematic. Winter sowing vegetables is an alternative to starting seeds inside that eliminates these issues.
Never heard of Winter Sowing Vegetables?
Winter sowing is a method where you start seeds outdoors in the winter, utilizing mini greenhouses made from recycled containers. The mini greenhouses are placed outside during the winter and exposed to the cold and snow.
You can use the winter sowing method to sow vegetable seeds anytime from December to mid March, as long as the weather is still cold. (Warmer zones may need to start their seeds earlier and stop winter sowing earlier.) The seeds remain dormant during the cold weather, then sprout as the weather warms.
Unlike seeds started inside, seeds started using the winter sowing method require little attention until the weather warms. The end result is a hardy plant that is acclimated to your area and needs no hardening off.
Winter Sowing Essentials
- recycled containers to make mini greenhouses
- quality potting mix
- seeds of choice – Baker Creek is my favorite place to order organic and heirloom vegetable seeds.
That’s all you need! See I told you this would be simple!
Seeds to Winter Sow – Best Choices for Your Vegetable Garden
Chances are, if you can grow it in your vegetable garden, you can winter sow it. About the only types of seeds that won’t work well are for tropical plants as these seeds are easily damaged by temperatures lower than 50 degrees.
For beginners the best seeds to winter sow are ones that that reseed readily in your area, or varieties that are cold-hardy. In my zone, I get tomato volunteers every year from the previous year’s tomatoes that fell off the plant. Ground cherries and basil also reseed in my area. So for my zone, these are good choices for beginners. Seeds from cold-hardy plants, like brassicas are also good choices for seeds to winter sow.
Feel free to experiment with a few seeds. If it doesn’t work, then you aren’t really losing much. If the seeds sprout, then make note of it so you can grow more next year. With vegetables, I have found most varieties I grow regularly in my garden are suited for winter sowing.
The only vegetable seeds I don’t use for winter sowing are peppers. Peppers need heat to germinate well. You can winter sow them when the weather starts to warm, but the plants will be small. So I leave those for starting inside under lights.
I like to use organic vegetable seeds in my winter sowing to make sure I am not using seeds contaminated with genetically-modified organisms (GMOs). Current organic certification in the United States does not allow anything labeled as “organic” to contain GMOs. So the only absolute way to avoid it is to buy organic seeds.
Containers for Winter Sowing
Winter sowing vegetables is a wonderful way to re-use containers that would have otherwise ended up in the garbage. Good choices for containers for winter sowing are
- milk jugs
- yogurt containers
- Aluminum foil pans
- paper towel or toilet paper rolls
- newspaper pots
- peat pots
- clear plastic clamshells (like from prepackaged salads)
- soda pop 2 liters
- seed sowing flats
If you look around your house, you will probably be amazed at how many containers you can salvage and put to use as mini greenhouses for winter sowing vegetables.
Preparing the winter sowing containers
All of your winter sowing containers need 2 things to ensure success – drainage holes and ventilation.
Drainage holes ensure that water does not build up and drown your seeds. Depending on the size of the container, I make drill 5-10 holes in the bottom using an inexpensive soldering iron. You can also use a 1/4 inch bit on a drill, but if your container is flimsy, it might crack.
Ventilation holes are necessary so that your seeds don’t cook before they get a chance to germinate. When the sun is out, heat can build quickly in these containers, so you want to make sure it can escape. As the weather warms, you may need to increase the size and number of your ventilation holes.
If you are using milk jugs or soda bottles, just leave the cap off. No additional ventilation holes are needed.
My containers of choice are large yogurt tubs, since my kids eat a lot of yogurt. To prepare the tub, I cut a circle from the middle of the lid to allow light to reach the soil. After planting the container, I lay a small piece of plastic wrap (or a plastic sandwich bag cut in half) across the top and then put the lid back in place. This creates the mini greenhouse.
I poke the plastic wrap several times with scissors for the ventilation holes and the container is ready to go sit out on my deck for the rest of the winter. Of course as it gets consistently warmer outside, I use scissors to quickly enlarge the ventilation holes. Eventually I can remove the plastic entirely.
Newspaper Pot Maker and Soil Block Maker – Handy Gadgets to Use with Winter Sowing
While not strictly necessary for winter sowing, us gardeners like our toys too! The newspaper pot maker and the soil block maker are two gardening gadgets are especially useful for winter sowing.
I use the soil block maker and newspaper pot maker for both indoor seed starting and winter sowing. I love that the newspaper pot maker allows you turn old newspaper into cute little seed starting pots. Since the newspaper will break down, you can plant the whole thing right in your garden when the seedlings are big enough to be transplanted. It works very well for seeds that don’t like their roots disturbed.
With the soil block maker, you can compact ordinary soil into the ideal growing container for starting seeds. I was skeptical at first, but these soil blocks hold up surprisingly well. I have even dropped a couple on the way to moving them into the garden. and they held together.
You can use either soil blocks or newspaper pots inside of another container for winter sowing. (They work well in those plastic containers that hold salad greens.) You just need to monitor the moisture level as the weather warms to make sure your soil doesn’t dry out.
Winter Sowing Soil
Since your containers are going to be sitting outside all winter, winter sowing soil needs to be light so that it allows air to reach the roots.
What not to use as winter sowing soil:
Soil that is too heavy will compress over time, which makes it harder for the roots to grow once the seed has germinated. Potting soils are too heavy to use with winter sowing. Plus, they may contain weed seeds which is a huge nuisance!
Seed starting mixes should also be avoided. Since they don’t contain any soil at all, they are too light and they dry out quickly. Plus they contain nothing to feed your growing seedlings so you will have to spend extra time fertilizing
In addition, you want to avoid any potting mixes that are designed to help retain moisture, such as Miracle-Gro’s Moisture Control potting mix. These are made for houseplants to increase time between watering. It is not the best choice for winter sowing soil. Your containers are going to be covered in snow and rained on frequently, so you want that extra moisture to drain away – not to be retained.
What to look for in a winter sowing soil:
Look for bags that are labeled “potting mixes”. These are a combination of potting soil and other materials like vermiculite, perlite, and peat moss. It is heavy enough to retain some moisture, but light enough that compacting isn’t an issue.
You can also make your own potting mix. I no longer buy bagged potting mix. I prefer to make my own from coconut coir. Coconut coir is made from the husks of coconuts and is a sustainable alternative to peat moss. It retains water well well still providing adequate drainage.
Coconut Coir comes in a brick. You just add warm water and it re-hydrates and becomes a fluffy soil in just minutes.
Homemade Winter Sowing Soil Mix
- 10 parts coconut coir
- 2 parts earthworm castings (get them here if you don’t make your own)
- 1 part vermiculite
- 1 part perlite
How much winter sowing soil to use:
I recommend at least 2-3 inches of soil in your containers to give the roots plenty of room to develop and ensure that it doesn’t dry out too quickly. In my yogurt tubs, I generally fill them to about 2 inches from the top because I let the plants hang out a little longer before planting out in my garden.
The Weather Is Getting Warmer. Now What?
As springtime approached, you will need to start monitoring moisture levels in your winter sowing containers. If you see condensation in the container, they are fine. If there is no condensation, you will need to water the soil well.
Keep an eye out for emerging seedlings. It is always so exciting to see that first bit of green! At this point, you will probably want to start increasing the ventilation. Remember, you are in essentially making mini greenhouses, so the temperature inside the containers can be a bit higher than the air temperature. You don’t want to fry your little babies before they even get started.
If your containers are covered in plastic, you can enlarge the holes. Covers can be propped open and lids can be removed during the day on seed flats and aluminum foil pans. My own personal rule of thumb is to ventilate when temperatures are above 45 degrees. In general lids and covers can be removed completely when temperatures are above 50 degrees at night.
When to Transplant Your Winter Sown Seedlings
You can transplant your seedlings anytime after they get their first true set of leaves. If you gradually increased the ventilation on your containers, your plants should be well-acclimated.
However, I prefer to let my plants get a bit larger in the protection of my deck before I transplant them to the garden. Make sure to water the plants thoroughly before you transplant them.
Winter Sowing Vegetables is Easy and Fun!
There are many benefits to winter sown vegetables.
- No damping off or gnats.
- No need for an expensive grow light setup.
- The seeds come up when the conditions are right in your area.
- No need to harden off your plants.
Plus it’s so much fun to play in the soil in the dead of winter!
Pin this winter sown vegetables post for later:
Why would you ever go back to starting your seeds inside??? So tell me… have you tried winter sowing vegetables? What did you grow?