Winter Sowing - Start Your Seeds Now for Faster, Simple Growing

Winter can be tough on gardeners. There’s only so much planning you can do before you start itching to get outside and get something growing. If you think snowy days mean you and your plants have to stay inside, you need to learn about Winter Sowing!

Winter sowing is a method of sowing seeds outdoors. But it is more than just directly sowing seeds into a garden. The winter sowing method uses plastic containers to shelter the seeds and allow the soil to warm up quicker. Sometimes this method is also referred to as Milk Jug Greenhouses since this is the most common container used in winter sowing. 

There are several benefits that gardeners appreciate about winter sowing:

• Natural cold stratification. The seeds will go through a cold period and receive the cold stratification they need to germinate.

• No extra care to harden off seedlings. Because the seeds are sown outdoors, they are already acclimating to the outdoor environment.

• Save indoor space. Growing lots of plants from seed? Winter sowing can free up the indoor grow space for plants that need a more controlled environment.

• Low-cost method. Using materials you already have can make it an economical way to start seeds.

• Earlier harvest. Cold-hardy greens will be ready to eat sooner in the spring. 

• Carefree. You can almost plant and forget about them. It’s that easy.

Cold-weather crops are a natural for winter sowing, as are plants that self-sow. Additionally, any seeds that need cold stratification or scarification. Check the seed packets to see which ones are good candidates.  

• Use a clean milk jug.
• Cut around the middle, leaving a hinge on one side.
• Cut drainage holes in the bottom.
• Fill with a seed-starting mix at a depth of 3 to 5 inches. 
• Sprinkle seeds on top of the soil and cover to a depth of about 1/4”. (Check individual seed packets.)
• Water the soil, so it is fully saturated but with no standing water. 
• Label the container with a waterproof marker. (Adding an additional tag inside is helpful.)
• Use duct tape to keep the lids on. 
• Set them outside in the cold and snow.
• When temperatures are 50 and above, you can open the tops.
• Close the tops when it is cold.

Place the containers out of the sun until you are ready for them to sprout. If you are in a very cold location, you will want a spot that gets some sun during the day. In a milder location, they can be in the shade, so they don’t heat up too much.

Traditionally winter sowing can start any time after the winter solstice. However, late January to mid-March works best, depending on your location. This is because the seeds will need enough time in the cold to make them go dormant before the weather warms up.

When you start with saturated soil, you shouldn’t have to water again until the seeds start sprouting. But keep an eye on them. Especially during warm spells to make sure they haven’t dried out or started sprouting.

Yes, your seeds will freeze. And that’s part of the germination process. Plants that self-sow drop their seeds and come back year after year.