Winter sowing: How to start seeds outdoors in winter

There is always time for winter sowing. Despite what you think, it is rarely too late in the year. But it can be too early.

You see, there are ideal times to sow in winter, and there are times that work but not as well.

Here in this article, I will show you two different winter sowing techniques. The step-by-step instructions are easy to follow and require a minimum amount of work. 

And no, you do not need to build a mini-greenhouse from a container.

And I know from experience that both these methods work.

Tip! Use leftover seeds and mix and match. Scatter seeds over an area or plant in rows until you run out, and then continue with another type of seed. Be creative and have fun with it.

I will also give you my top 9 vegetables to winter sow.

2 easy-to-follow winter sowing techniques

You can face rock-hard frozen soil and snow when you plant seeds in winter. But there are also times when the ground is still soft and easy to work with.

Winter sowing is traditionally linked to stratification, where some seeds need to be frozen for the period of dormancy to be broken [1]. The seeds freeze and then later germinate as the weather turns milder. But I have found winter sowing to work well for many different types of seeds.

Here in zone 7, we can, most years, work the ground for at least the first 5-10 days of December. 

But as it varies, I have used both techniques in the past.

Wear gloves as winter sowing does get cold
Gloves are a must, as it does get cold.

The first method is ideal when the ground is frozen. The other technique is better suited for soft and workable soil. 

Winter sowing when the ground is frozen solid

We can still plant seeds for spring when the soil freezes and go rock hard. I would not call it a garden hack, but it does feel somewhat counterintuitive and speaks to the rebellious part of my gardener self.

Materials needed:

  • Gloves
  • Rake, spade, or be prepared to use your hands
  • Seeds
  • Well-draining soil
  • Mulch (optional)
  • Water

Step 1: Clear the area where you will sow. Remove weeds and debris as needed.

Clearing the area by hand

Step 2: Place seeds on the frozen ground

2. Place or scatter the seeds on the frozen ground
Scattering spinach seeds on the frozen bed

Step 3: Cover seeds with fresh soil from a bag 

3. Covering the seeds with fresh soil from a bag
Covering the seeds with fresh soil

Step 4: Water lightly using a rose (or place a thin layer of snow on top)

Step 5: Mulch the area (optional)

4 Winter sowing completed. Not adding mulch as planting for spring harvest.
Winter sowing is complete—no mulching as planting for spring harvest.
Tip! Check the seed packet for recommended planting depth for the seeds you are planting. Now cover the seeds by adding the corresponding amount of soil on top of the seeds. 

Winter sowing in warmer soil temperatures

Planting seeds in fall and winter when the soil is still soft follows a more traditional pattern. 

Materials needed:

  • Gloves
  • Spade
  • Seeds
  • Mulch (optional)
  • Water

Step 1: Weed and clear the area where you will sow

Step 2: If the soil feels dry, water lightly

Step 3: Plant seeds at desired depth and cover (check the seed packet for planting depth)

Step 4: Water 

Step 5: Mulch (optional)

Keeping the seeds healthy over winter

There are, of course, things that can go wrong with winter sowing. As with all gardening, we have no control over shifts in temperature, precipitation, and other curveballs mother nature can throw at us.

And then, there is, of course, the human factor. We mean well, but our actions have an adverse effect.

Here are the 3 main factors to be aware of. And as gardeners, we observe and do what we can to protect our crops.

1. Sowing your seeds too early 

Ironically colder regions can be better suited for starting seeds in winter. 

When the temperatures are freezing, the seeds pause to come alive again as the temperatures warm up in the spring.

In milder climates, you can have cold spells with freezing temperatures followed by milder periods followed by freezing temperatures. 

Here you have the risk that the seeds will germinate and sprout too early to be killed during a second or even third cold spell.

Ideally, you are looking for a cold winter with low, stable temperatures followed by a spring with a gradual increase in temperature. And this is, of course, what I wrote on my holiday wishing list this year!

Tip: Do not plant seeds too early. Wait for soil temperatures below 5 degrees Celsius (40 degrees Fahrenheit) to prevent seeds from germinating and sprouting too soon. 

2. Should I mulch and use a protective cover when winter sowing?

Sometimes less is more. And this can be true for mulching and using a proactive cover when winter sowing.

But first things first, mulching and using protective covers serve different purposes.

Mulching insulates and helps protect against large swings in soil temperature.

Protective coverings create a mini greenhouse effect that raises the temperature and stimulates growth.

Come fall and early winter, there is still a lot of residual heat in the ground. When you mulch and use a protective cover, you raise the temperature.

If you are planting in late fall or early winter, this temperature rise can lead to seeds sprouting too early to be killed off by the first onset of freezing temperatures and frost.

This is my golden rule: 

  • When planting for same-year harvest – mulch and use a protective cover as needed.
  • When planting for early spring harvest next year – mulch, but do not use a protective cover.
Tip! When planting for same-year harvest, consider keeping the soil covered at night if you expect extreme drops in temperature.

3. Overwatering by act or omission

As with all gardening, do not overwater. When the seeds are frozen in the ground, they are on pause and do not need extra moisture. Resist any temptation to water a rock-hard frozen garden bed.

And then we have the mild winters where snow is nowhere to be seen and is replaced by rainfall. Cover your beds with a cardboard paper or another protective cover during heavy rain, especially if it goes on for days.

Tip! Even well-draining soil can retain too much moisture when the ground is semi-frozen. Watch out for puddles of water.

Best 7 vegetables to winter sow for beginners

Winter showing is easy, and there is always room in the garden. But not all vegetables are suitable for winter sowing. Some seeds need warm temperatures and light to germinate and will die if left in the ground over winter.

But then there are those vegetables that tolerate and sometimes even thrive in colder temperatures.

Trust me; it feels great to harvest fresh vegetables in early spring when most other gardeners are yet to start their season.

My top 7 vegetables to winter sow for an early spring harvest.

1. Spinach 

Spinach is an ideal cool-weather leafy green that prefers cold to hot summer temperatures. 

Use fresh in salads, in soups, sauces, and stews, or freeze for later use.

Harvest early for tender baby spinach leaves or leave to mature and use for cooking and stir-fries.

2. Corn salad 

Corn salad, lamb’s lettuce, or mache is a low-growing leafy green. 

Harvest the entire plant or individual leaves and watch the plant re-grow. Corn salad is very hardy, and there is something special about harvesting a fresh leafy green growing under a layer of snow mid-winter.

Use fresh in salads or stir-fries. 

3. Kale

Nero di Toscana is my favorite variety, but you can choose another hardy kale variety. And kales are usually quite hardy by nature, so do not be afraid to experiment.

Harvest the long, dark blue-green leaves and use fresh or lightly stir-fried. Nero di Toscana is a fast grower. Before you harvest, wait for leaves to reach at least 20 cm (8 inches).

4. Carrots

Carrot seeds germinate at 5 degrees Celcius (40 degrees Fahrenheit) but will happily overwinter in freezing temperatures.

Same as with horseradish and parsnips, plant seeds in fertile soil free from stones, roots, or other objects that can interfere with carrot growth. 

If you need to thin out your plants in spring, cut them to avoid disturbing the roots of the remaining plants. 

Use fresh, in stir-fries, and with all types of cooking.

5. Parsnip

Parsnip seeds suffer from low germination rates, and you need to sow 4-6 seeds for each plant.

Parsnip seeds scattered densely as the germination rate can be poor
Parsnip seeds are scattered densely as the germination rate can be poor

Thin out the plants in spring for fewer and larger parsnips or leave all plants to compete for nutrition for more, smaller-sized parsnips.

Parsnips are slow to germinate. Water frequently to avoid dry outs.

6. Arugula 

Arugula or rocket salad is another favorite with a mustard-peppery taste that ensures a little goes a long way.

Leave about 2 inches between plants to give them room to grow. Or scatter seeds densely to harvest tender and fresh baby arugula leaves as the plants sprout.

Use fresh in salads or add to stir-fries 30 seconds before serving.

7. Tatsoi

A close relative to corn salad, tatsoi can be harvested by the leaf or cut the whole plant. 

Tatsoi is low-growing, and the dark green leaves form a compact rosette. 

Use fresh in salads or combine with, for example, garlic in stir-fries. 

Winter sowing summary

I have introduced many local home gardeners to winter sowing.

Most start with disbelief and leftover seeds. But 9 times out of 10, these same home gardeners become avid winter gardeners.

The only downside to winter sowing is that it is a bit inconvenient to garden in the cold.

But apart from this minor inconvenience, it is both simple and easy, and most of the time, you will have leftover seeds waiting to be planted.

Give it a try, and I would love to hear about your results.

Helpful resources:


Meet the author: Sarah is a freelance copywriter passionate about gardening - particularly creating kitchen gardens with fruits, vegetables, and edible perennials. She has a professional background in the travel industry and now combines her interests with her writing skills to contribute articles on travel and horticultural topics for publication across the internet.