When to Start Winter Sowing: The Right Time for Your Zone

Winter sowing has many advantages, including the tremendous convenience of not dealing with the mess of indoor seed starting. If you’ve been dealing with the cold weather blues, getting some plants started may be just the thing to chase the gray away. 

Starting your seeds indoors works fine for many plants. However, it has some definite disadvantages. Fungal diseases are more likely for these, and those that need cold stratification require more work. Those will have to be artificially exposed to cold for some time to see a good germination rate. 

Winter sowing takes these troubles away and simplifies the process of germinating many seeds altogether. Timing is an important aspect of getting this process to work as it should. Let’s talk about when you should get started on winter sowing according to your climate zone.

The Long Answer

When to start your winter sowing depends primarily upon your climate. We delineate this with growing zones, which include Zones 1-13. Before we get into timing, let’s talk about the benefits of this type of seed starting. 

Benefits of Winter Sowing

The benefits of winter sowing are significant when you consider the space, money, and time you will save. It also creates more ideal conditions for many plants and increases your germination rate. Let’s dig in. 

Cost Saving

Winter sowing involves starting your seeds outdoors, in containers, during the colder months. One way to save money doing it this way is by repurposing various containers rather than using more costly seed starting trays. That’s not to say that those trays don’t have their perks, but for this project, you can save them for another season. 

Use items like milk jugs and other clear plastic containers to start your seeds. These will weather the snow, and you don’t have to worry about them cracking or breaking because you don’t need to reuse them again. You can simply recycle. 

This method also uses natural light for germination, so there is no need for grow lights. It saves on your electric bill and conserves those lights for seeds that you need to start indoors in the warmth. 

Time Saving

Starting your seeds this way is also a good way to conserve time. Starting them indoors can be time-consuming. Unless your lights are on a timer, you’ll need to remember to turn them off and on at the right times daily. 

You don’t need to worry about watering them either, as long as the natural weather conditions keep up with their needs. You can check on them during warm spells or when there has been a shortage of precipitation. Chances are good that they will be fine without intervention. 

Because they are growing under natural light, there is no hardening off period. This eliminates a lot of the time and trouble of starting them indoors. They will develop stronger stems and roots and be tougher when it’s time to transplant.

Space Saving

Planting this way can save you a ton of space, too! If you have a dedicated seed starting area or a greenhouse, this won’t matter much. If you start your seedlings in the garage or other area of the home, however, this practice will help make that space available for other endeavors. 

Getting your garden started in the home can prove quite messy. I’ve certainly overturned an entire tray indoors by accident. Not only are those plants lost, but the cleanup is a messy job. Sometimes, we can’t avoid starting them indoors, but starting the ones that we can outdoors will save a significant amount of space. 

Prevent Damping Off

Damping off is a fungal disease that affects young seedlings. If you’ve ever had a large number of plant babies rot in the pots, you’ve probably experienced this phenomenon. This is not nearly as big an issue with seeds started outdoors. 

The most common causes of this fungal disease are soil that doesn’t drain well and planting too deeply. If you set your cells in a tray full of water, you’re looking for trouble. The soil-borne fungal pathogens that cause damping off thrive in cool, damp environments. Poor air circulation doesn’t help, either. 

Cold Stratification

Many seeds require cold stratification for optimal germination. Those woody perennials are the most common. The freezing and thawing process helps to break down their seed coat, which makes it easier for water to penetrate and for them to germinate. This is not exclusive to woody perennials, though. 

You can carry out this process artificially, but it’s more work for you. It requires monitoring the moisture levels. It also requires some prep work, and you have to be ready to plant them at the right time. 

If you plant them outside while the weather is still going through the freezing and thawing cycles, nature will do it for you. It will also, more than likely, do a more thorough job of it. 

Seed Protection

This has more to do with using containers for the process rather than directly sowing in the ground. By planting in containers like milk jugs and other plastic containers, you protect them from some external factors.

Planting in containers prevents animals from eating your seeds or scratching up the soil and moving them around. For those that need light to germinate, you’ll need to surface sow. Those can easily blow around and get displaced by the wind or rain.

Prolong Growing Season

Finally, this practice prolongs your growing season by having those seeds outdoors in their element at just the right time. There is no guesswork about frost dates and no hardening off, which can take more time away from their rapid growth period. 

Essentially, you are leaving to nature, that which nature knows how to best achieve. This may seem counterintuitive since you can technically start indoors long before the ground thaws. However, winter sowing speeds up the growth process and produces stronger seedlings earlier in the season. 

Timing It Right for Your Zone

So, let’s get down to the real topic at hand. How should you time your winter sowing based on the climate where you live, and when should you start? I’ve often heard it said that the winter solstice is a good time to begin, but it truly depends on your first and last frost date. 

You don’t want to begin too early in a warmer climate. If the weather gets cold and then warms up enough for your seeds to germinate, they will sprout and may die off in successive frosts. It’s important to wait until you can be certain that the weather will be consistently cold. 

Once you are certain that the long-term cold weather has arrived, you can plant certain things. This is the time for native plants and perennials that need stratification. You want these seeds to endure the coldest months of the year outdoors. 

Many of these have seeds that require that period of freezing and thawing to break dormancy. Some of these have a hard coating that allows them to remain dormant through the winter. They need the most time to break down their outer coating so that water can permeate. 

The ideal time to sow seeds for cold weather crops, hardy annuals, and hardy herbs is about six to eight weeks before your last frost date. These don’t require the same length of cold weather to germinate, but most will germinate better when exposed to some cold. 

As far as timing these for your zone, the farther north you live, the earlier you can start with your first group of winter sowing. But also, northern areas should sow the second group later. As you move farther south, the span of time between these events will decrease.