I love starting seeds indoors. It’s a great way to get a jump start on the season – to play in the soil even when the temperatures outdoors are sub-freezing. Growing seedlings indoors can be a little tricky though. Plus, those seed trays take up space that not all homeowners are fortunate to have. It was space limitations which led one gardener to get creative and find a different solution. Her approach is the subject of today’s podcast; winter sowing, a simple way to successfully start seeds outdoors.
Trudy Davidoff was a novice seed starter who was challenged for space. Her small cottage in New York didn’t provide the room she needed to accommodate seed trays. After a little research, Trudy learned that many varieties of seeds require a chill period to trigger germination. So, she decided to try to mimic what happens naturally.
She sowed seeds in containers in late winter, left the containers outdoors and waited to see if they would germinate in the spring. Without supplemental water, fertilizer or special coddling; the seeds did germinate, and as the temperatures rose so did Trudy’s seedlings.
Flash forward a couple of decades, and Trudy’s methods are becoming more popular. What’s not to love? After all, some of the best tools for winter sowing are repurposed materials you already have in your home, and winter sowing couldn’t be much easier. Once the seeds are in the growing medium, you can practically forget about them until they are ready to transplant into your garden beds.
Winter Sowing Benefits
Gardening can be an expensive hobby. It doesn’t need to be, and starting your own plants from seed is a great way to save money. Well, winter seed sowing is about as low cost as it gets. The only thing you really need to invest in is the soil, but that won’t set you back much either.
There are lots of seed exchange groups where you can get seeds for free or for very little cost. Even if you purchase seeds, the cost of a couple of dollars is so worth the payoff. You can buy packets of seed just about everywhere these days, but this is another example of “you get what you pay for.” Quality matters – not just in how many seeds will germinate but it can also play a role in how healthy your mature plants will be.
I recommend looking for organic seeds. Whether you get them from an exchange or you spend an extra dollar to purchase organic seeds, the plants you grow will be healthier as a result of their parent plant not having been treated with or exposed to chemicals.
Great container options for winter sowing are items you’ve already got around the house – like milk jugs, take out food containers, and other large plastic containers with deep bottoms and clear tops. You probably have duct tape and a marker on hand too.
Here’s what you won’t need for winter sowing: special lights, heat mats or fans. This method is a sort of “tough love” approach to seed starting, but it’s really just mimicking the natural process. It saves you money on your power bill too.
Another avoidable but common problem to seedlings started indoors: they are at risk for developing a fungal disease known as “damping off.” It kills seedlings at the soil surface – usually as a result of inadequate air circulation. With winter sowing, that’s not a problem.
Winter sowing is also a time-saver. Since seedlings will be growing under natural light and temperature conditions, you won’t need to invest time in hardening them off before they go into your garden beds. They will already be acclimated, and they’ll be hardier and stocker than if they are grown indoors without sufficient light.
I love starting seeds indoors, but the hardening off process can be time-consuming.
I’ll admit, in spite of the extra work, I prefer starting seeds indoors. I like the hands-on care they require and being able to watch as they emerge from the soil and mature into new plants bursting with life. There’s something about observing the daily miracle of growth that I never get tired of. That said, if you’re the type of gardener who would prefer to sow it and forget it, winter sowing is right up your alley.
If you haven’t tried it before, you might worry about your seeds freezing. Don’t. In nature, seeds freeze all the time. Freezing actually prolongs the life of seeds, and some types require a freeze (or very cold temperatures) in order to germinate at all.
What you need to watch for instead is sowing seeds too early in the winter months. If a short, early warm spell comes along; the seeds could germinate too soon. Then when the temperatures plummet again, the young seedlings won’t be mature enough to power through. For those of us living in the Northern Hemisphere, a good rule of thumb is to wait until around Christmas before we start our winter sowing.
What to Sow
There are so many varieties of seeds that are great candidates for winter sowing. Edible cool-season crops, flowering plants, herbs – you have a lot of options to choose from when you’re ready to give this method a try.
Let’s start with perennials. The first quality you should look for when determining if a seed variety is a good winter sowing candidate is the hardiness zone that is appropriate for the perennial plant you’re considering. If it’s naturally hardy in your zone, odds are good that it’s a good option for winter sowing.
Check the seed packet. If there is any mention that the seeds need to be stratified or scarified, that’s another good indicator of a seed type that will respond well to winter sowing.
In general, seeds require some sort of trigger to break their dormancy and cause germination. Stratification is the process of using prolonged periods of cold temperatures to break dormancy.
Consider what happens in nature. Certain varieties of seed fall to the ground and have to ride out winter before they sprout. If they germinated immediately after they made contact with the soil, they wouldn’t survive the winter season.
It’s only after a certain period of time in cool or freezing temperatures that they become ready to germinate. This process can be mimicked by placing the seeds into a refrigerator or a freezer, but winter sowing eliminates the need for that. The seeds are exposed to the cold temperatures of the natural environment and break dormancy as the days grow longer and the soil becomes warmer.
Milkweed is a great example. It’s tricky to get milkweed seeds to germinate unless you provide the proper chill period. So, winter sowing is a much easier solution for providing the conditions milkweed needs.
The term scarification is another signal of a good winter sowing option. Lots of seed varieties have a hard outer coating designed to protect the seed embryo. In nature, those hard shells are broken down in a variety of ways – including the digestive system of birds or other creatures, as well as freezing temperatures.
Scarification is the process of manually weakening the hard seed coating. This can be done in many ways, but with winter sowing, it’s unnecessary. The freezing temperatures can weaken the seed coat naturally.
Other terms to look for in seed varieties you are interested in winter sowing:
- sown when cool
When you spot those on a seed packet or in a seed description, you can feel confident about trying the winter sowing technique.
The varietal name can also provide clues about their winter sowing viability. Alpine, polar, Siberian, oriental, arctic – notice a trend? Those varieties were so named, because of their native climate or their ability to withstand freezing temperatures.
You can sow seeds of Siberian iris, Oriental poppy, and Arctic daisy and place the containers outdoors through late winter to propagate your own, inexpensive seedlings for the garden.
There are plenty of hardy annual options too, and the seed packets of those plants will often feature the same key phrases.
What constitutes a “hardy annual?” Those are plants that complete their lifecycle in just one year and which can tolerate a light frost. They germinate, mature, produce, and die within a 12-month period, but they won’t resprout. Instead, they set seed for the following year’s new generation and can sprout in place, without the need to germinate indoors.
Some examples include snapdragon, bee balm, and delphinium; and that’s just the tip of the iceberg. There are so many options to try.
Some edible options for winter sowing include the classic cool-season crops – like broccoli, cauliflower and cabbage. Leafy greens – like lettuce, kale and bok choy – are also hardy annual options. Herbs like sage, oregano, dill, and mint are good winter sowing candidates too.
In any case, what’s the harm in trying? If there’s a variety that you want to try winter sowing for your garden, don’t be afraid to experiment and see what happens. If those seeds don’t germinate, the most you’ve lost is a packet of seeds, but you’ve gained a learning experience. The risk is so inconsequential in comparison to the potential reward.
You might have noticed some varieties that I haven’t mentioned as good candidates for winter sowing. Summer edible crops including tomatoes, squash, eggplant, and peppers all need warmer temperatures. For those types of plants, indoor seed starting really is your best bet to get a jump start on the season.
If you’ve never tried starting seeds indoors, trust me – you will love it. It takes a bit more effort and space, but to be honest, it’s one of the most rewarding aspects of gardening for me. Maybe for you too.
How to Winter Sow
In nature, seeds which are cold hardy can weather freezing temperatures, but keep in mind that they get a little natural protection too. Those seeds fall to the ground and are inevitably covered by leaves and other debris to offer a little bit of insulation.
In winter sowing, you need to provide a little protection too, while containing them so that you can transplant them into your garden or landscape beds in spring. So, your goal is to create a sort of mini-greenhouse.
Look around your home, and you’ll find all kinds of options ready and waiting. Look for anything clear or slightly opaque to let in sunlight. It also needs to withstand freezing temperatures and if it has a handle, that’s ideal.
I’m not a fan of plastic, but it’s just a fact of our modern-day life. Fortunately, it’s the perfect material for winter sowing. Plastic milk jugs are the classic choice. When cut in half, they offer plenty of space along the bottom, and the top lets in plenty of light and traps some heat and moisture.
Two-liter soda bottles are another good choice as are lots of food take-out containers with clear plastic lids. Do you ever buy a rotisserie chicken? Save the container, because it works great for winter sowing.
Once you’ve got your container, you need to create opportunities for drainage and for air and moisture venting. There are plenty of ways to poke some holes in the top and bottom of the container for this, but my favorite is to use a Phillips-head screwdriver. I heat up the tip of the screwdriver and touch it to the plastic. It melts a quick and good-sized hole without much effort.
Don’t be stingy when you’re making those holes. You’ll want several along the bottom, so there’s no risk of water pooling at the base of the soil. The top of the container needs plenty of holes as well for venting.
If you’re using a milk jug or a soda bottle, slice around the circumference about 5-6” from the bottom. Don’t cut it completely off. Instead, leave about an inch to work like a sort of hinge for the lid. Voila! You’re ready to winter sow some seeds, my gardening friend.
Next, you’ll need soil. Seed starting mix is an option, but since you’re trying to replicate natural conditions outdoors, you don’t need to use a medium that is sterile or as light as is necessary for indoor seed starting. On the other hand, garden soil is a little heavy for this technique, so I don’t recommend that. Regular potting or container soil is perfect.
You’ll need enough soil to allow room for the roots to develop once the seeds have germinated. The seedlings can’t be transplanted into the garden until they have established enough of a root system to rebound after being handled. A soil depth of about 4” is a good rule of thumb for winter sowing.
Sprinkle your seeds over the surface and very lightly tamp them down with your hand. Use a light touch to sprinkle a very thin layer of soil over the top of the seeds too. It’s better to use too little than to overdo it here.
Water them in gently, then flip or place the lid over the top. Duct tape works great to secure the top to prevent it from being blown or knocked off, because it’s so durable – even under harsh conditions.
Don’t forget to label the container with the type of seeds you’ve sown. Any type of permanent marker will work, but remember that the container has a few months of harsh conditions in its future. You would be surprised how quickly even permanent markers fade under the circumstances.
That’s why I like to use a paint pen instead. Those are readily available and are least likely to fade in the UV light and cold temperatures. I write the seed variety on the top of the container, but I provide myself a little insurance too. I also write the seed variety on the bottom of the container. The bottom won’t be exposed, so I can know that, come spring, I won’t have to rack my brain to remember what the heck I have thriving and ready to plant.
Curb Your Enthusiasm
The most common winter-sowing problem is the mistake of starting seeds too soon. The winter solstice (December 21st) is a good rule of thumb to go by. That’s one of the busiest times of the year for most of us, so if you don’t have everything ready to go until after the first of the new year, don’t worry.
I don’t usually do my winter sowing until sometime in January, and that might be a perfect time for you too. It’s the perfect way to scratch that gardening “itch” even though the weather outside is still frightful.
Even into February, your area is probably still experiencing cold enough temperatures for several weeks, that your winter sowing container will still be exposed to a sufficient chill period for the seeds which require that time. That said – if you live in a milder climate and pick seeds appropriate to your zone, those varieties won’t require freezing temperatures for successful germination. After all, this technique is all about mimicking what happens naturally in your area.
Once your seeds are sown and the containers are taped up and ready to go, where’s the best place to put them? That depends a little on where you live. If you’re in a colder climate, a sunny spot with access to natural moisture is ideal. Once they germinate, the seedlings will benefit from the warmth of the sun.
On the other hand, those of you living in a milder climate should choose a spot with a little shade. A little warmth is a good thing, but those containers will heat up quickly, so you don’t want to cook them inside that mini-greenhouse you’ve created.
In either case, avoid any area which is exposed to heavy wind. If the containers get knocked around, it will disrupt root growth and can kill your seedlings. That’s why it’s also a good idea to protect them from being disturbed by animals or foot traffic too. So if you can elevate them on a table or a ledge, that’s your best bet.
As the temperatures start to warm, be sure to check on germination periodically. Once the seedlings begin to develop, they’ll need larger openings in the container to provide more air circulation. They’ll also need a little bit of water, so don’t let the soil dry out.
On warm days, it’s a good idea to open the top of the container altogether to keep the air temperature around the seedlings from getting too warm. This little bit of maintenance and attention will be happening in early spring, so odds are pretty good that you’ll be anxious to get outside and get gardening anyway.
When the seedlings are tall enough to reach the top of the container and have a root system that’s sturdy enough to hold together, congratulations! They’re ready to transplant into the garden.
All in all, winter sowing is an easy and fun way to get gardening – even in the middle of winter – and grow flowers and cool-season crops for a low-cost investment of your hard-earned budget.
If you’re ready for more on winter sowing, keep an eye out for my Master Seed Starting course coming in January. You can sign up now to be notified and check out more details once the course has launched.
That course will really give you a leg up on starting seeds indoors. For all your summer crops – or if you’re like me and just love the experience of watching the daily development of these little green miracles – indoor seed starting is where it’s at.
I’ve been testing all kinds of indoor lighting options and doing comparison studies to find out what equipment is worthwhile and what’s just a waste of money. I’m also comparing which growing mediums are easiest to maintain and promote the healthiest seedlings. The course also covers sowing seeds directly into the garden too. And if you want a peek and the products I love, use and suggest you consider, I’m starting to list them all in my new Amazon Storefront. Check it out!
If it’s related to growing plants from seeds – no matter which technique you choose – this course will answer your questions and have you mastering the art of growing your own plants for all the seasons ahead of you. I’ll also be inviting students to live Q&A webinars to ask any followup questions or help troubleshoot. So, don’t miss it!
Don’t miss this recording either. You can scroll to the top of the page and click the Play icon in the green bar under the page title. I’m describing additional variety examples and talking you through the process.
Okay – so, which seeds will you be winter sowing this year? Let me know in the Comment below or share your success stories and lessons learned.
Links & Resources
joegardener Online Academy: Master Pests, Diseases and Weeds – Just $47 for lifetime access! Watch for my new course on seed starting coming soon!
https://www.amazon.com/shop/joegardener Our new Amazon Storefront. Here is where you’ll find my favorite must-have gardening gear, seed-starting equipment, books and more.