Winter Sowing in Zone 5 – Planting Seeds in the Snow!

It is the middle of February here in Iowa. We are in plant hardiness zone 5a. Winter is the time of year I plan the garden, and then have to fight myself to keep from starting seeds indoors too early. If you are a gardener, I am betting you know how that feels!

Well guess what? I am sowing some seeds outside RIGHT NOW – in the middle of winter.

What is winter sowing?

Winter sowing is the practice of starting seeds (flower and vegetable) in containers in the middle of winter and putting them outside in the snow and freezing temperatures. The idea is that the seeds will naturally germinate and sprout when nature says it is the right time.

Have you ever had a “volunteer” plant just come up in your garden? I have had onions, tomatoes and other plants just pop up from time to time in the spring without having planted any seeds. The seeds from the plants the prior year had survived the winter and had come up on their own when the time was right. This is much like the idea of winter sowing.

Winter Sowing in Zone 5 Video

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Spring is busy for a gardener! If you start your own seeds, there is a lot of trying to make sure the seeds have enough warmth to germinate and that seedlings are getting enough light and the right kind of light. You need to also make sure the seedlings have water, but not too much water. In many cases, it is basically trying to make some southern facing windows more like a greenhouse.

Not to mention different seeds need to be started at different times so that they are ready to plant outside when the time comes. It takes quite a coordinated effort when you stop and think about it. All of the above is what makes winter sowing such a fantastic idea.

5 Benefits of Winter Sowing

1. Winter sowing uses the natural warmth and light of the sun. There is no need to worry about if your seeds have enough warmth or light to germinate and grow.
2. Unless there is some unusually dry weather (no snow or rain for a long period), you do not need to water any of the seeds.
3. You do not have to stick to a seed sowing schedule. The seeds will germinate and grow when nature says it is time.
4. There is no need to “harden off” seedlings before planting in the garden. The plants are already used to the outdoor climate.
5. The plants produced with winter sowing are often healthier and yield more. At first, the plants may seem smaller than if they were started indoors, but once in the garden, winter sown plants quickly catch up to and many times surpass plants that were started indoors.

In addition to these benefits, read on and see how natural and simple winter sowing is. You will wonder how in the world sowing seeds got so complicated for the average home gardener.

How to Winter Sow Seeds

It should be noted that anything that normally grows well in your plant hardiness zone should be just fine for winter sowing. Obviously, if you live where there are cold and snowy winters, you should not try to grow a tropical plant with winter sowing.

When to Start Winter Sowing

As soon as temperatures in your area are consistently below freezing, you can winter sow. The seeds will remain dormant until the right time to sprout in the spring. Some people wait to winter sow the more tender plants (like tomatoes) until March. However, the seeds should remain dormant if planted earlier, so I am not sure that is entirely necessary.

Gather Supplies for Winter Sowing

1. Containers – These should allow light to pass through and allow for at least 4 inches of soil depth in the bottom. The popular choices seem to be milk jugs and clear totes with clear plastic lids. The possibilities here are really endless. People winter sow seeds in all kinds of containers. The common theme, however, is clearer plastic for at least the “lid” portion of the container and a bottom that allows for at least 4 inches of soil.
2. Potting soil – Use a good quality potting soil – not seed starting soil. If the potting soil is being kept in a location where it is frozen, bring it indoors a few days before planting.
3. Paint pen to label containers – To mark the outside of your containers. A sharpie is not going to work here. There are many reports of sharpie coming off while the containers are outside. Remember that the label will need to survive winter weather conditions and may be buried in snow depending on where you live.
4. Plant labels/markers for inside the container (optional) – Just in case something should happen to the outside label, an additional marker inside the container would help to identify the plants.
5. Duct tape – You will need to make sure lids are securely sealed around all edges if using containers you need to cut.
6. Seeds! – Though you can try winter sowing any seeds, the best outcome will be from seeds marked with terms like “direct sow outside in fall“, “self sowing”, “direct sow outside in early spring”, “cold hardy”, “cold stratification”, or “perennial”.

Prepare Containers

Make drainage holes in the bottom of the container if holes are not already present. An easy way to do this is with a drill. If you do not have a drill, using a sharp knife to make some small “X” cuts in the bottom will be enough for proper drainage.

Cut containers as necessary. We are mainly using milk jugs. After a good rinse, we cut the jugs on three sides allowing enough room at the bottom for 4 inches of soil. Cutting on three sides allows for opening and closing the container easily.

For ventilation, just leave the cap off of the top of the milk jug. If you have a solid lid on your container, you will need to supply some ventilation holes.

Prepare Soil and Add to Containers

Make sure the potting soil has been well moistened before adding to containers. The soil should not be water logged, but should hold together well when making a clump with your hand. If you skip this step, it can be difficult to make sure all of the soil in each container has plenty of moisture.

Add soil to a depth of 4” or more in each container. You can use less than 4” of soil, but the containers will dry out more easily and you will need to keep a closer eye on adding extra water if needed.

Plant Seeds According to Seed Depth on Package

You can plant seeds closer than you normally would, since these will be transplanted into the garden when they are still seedlings. You should pay attention, though, to the planting depth on the seed packet.

For tiny seeds, like onions, you can just broadcast the seeds all over the container instead of trying to plant individual seeds.

Mark and Seal the Containers

Adding a marker to the inside of the container is a good idea in case the outside label wears off in the winter weather. Marking the outside allows for quick identification. Use a paint pen on the outside to help ensure the label will stay there.

Seal the containers with duct tape or other heavy duty tape around the edges. This will help to retain moisture inside the container for the duration of the winter/spring.

Put the Containers Outside

The containers should be placed where they will get weather and partial sunlight. Avoid putting the containers under an awning or porch roof. Snow and rain will provide extra moisture and together with the sun your seeds will have good natural conditions.

If you get an extended period with no snow or rain, or you notice the soil is dry, you will need to water the container either through the holes in the lid or remove the lid to add water. An idea to make an easy watering tool is to poke holes in the lid of an empty plastic soda bottle, fill the bottle with water and use it to sprinkle water inside the top hole of a milk jug.

Care of Spring Seedlings

Once it is warm enough for seeds to germinate, check the amount of water in your containers from time to time and remember the container is like a small greenhouse. It can get hot in there. When it gets above 50-60°F outside, you should open or remove the lid from your containers to allow the buildup of heat to ventilate and to give your seedlings some fresh air. Close or replace the lid at night when the temperature drops back down.

You could also add some additional ventilation holes in the tops of the containers at this point to help with heat buildup.

So there you have it! A “set it and forget it” type method for starting seeds. Once you are ready to plant your seedlings, you might want to check out some of my other articles on gardening. Come on, spring!