Starting seeds outdoors instead of indoors produces strong, healthy plants that are already acclimated to their environment. Also known as “winter sowing”, starting seeds outdoors in containers is simple and doable in temperate climates. You can plant your seeds in containers right after Christmas and wait for them to sprout in the spring. Stop creating a huge mess indoors with your seed starting – move it outdoors!
Winter Sowing – Starting Seeds Outdoors
I’ve been gardening for over twenty years and in all that time I’ve always started my seeds indoors. Starting seeds indoors kept the seedlings close to me as they developed so I could keep an eye on them. It also provided a controlled environment to protect the baby plants from too much wind, water, drought, sun, and shade.
In short, it seemed like the best way to keep my seedlings safe and healthy.
However, after trying several methods of starting seeds outdoors, I’ve finally determined that outdoor seed starting produces healthier seedlings that are precisely acclimated to their outdoor lives. The benefits of starting seeds outdoors are discussed again further on in the article.
Winter Sowing Lingo
The first thing to do is clear up a little confusion that sometimes occurs because of the contemporary name of this outdoor seed starting process: Winter Sowing.
Starting seeds outdoors in containers can be done anytime of year, regardless of temperature. The novelty of this fact and the joy that a gardener can find sowing seeds IN WINTER has meant that the title of “Winter Sowing” has stuck. Which is great!
However, you can follow the process of “winter sowing”, or starting seeds outdoors in containers, during the growing season and into the fall garden, as well.
In temperate climates, this means that you can typically start sowing seeds in containers and placing them outdoors in December (or whenever your first truly cold month is) and then continuously sow more seeds until the late summer when you can start planting for the fall garden.
There are some exceptions to this that we talk about later on but this is generally a good rule of thumb. Green thumb, we hope, because this method produces fantastically strong, healthy seedlings!
Three Methods of Starting Seeds Outdoors:
- Direct sowing, planting seeds directly into the soil in the garden. Direct sowing has its pluses and minuses, which are outlined in the article Direct Sow Herbs.
- Starting seeds outdoors in grow trays inside a greenhouse or grow tunnel.
- Starting seeds outdoors in containers, also called “winter sowing”.
Starting Seeds Outdoors or “Winter Sowing”
The first thing to know is that you can start any non-tropical seed from December up through the end of your growing season in the late summer in most areas. I live in growing zone 6 and plant my seeds in containers outdoors right after I put away my Christmas decorations the first week in January.
I usually have a goal to plant the first week of December but I’m always too preoccupied with holiday fun. Which is perfectly fine – tis the season, after all!
I plant my seeds in their containers, place them outside, weigh them down against winter winds, and don’t think about them again until spring knowing that the seeds inside will germinate when they’re ready. It’s that easy!
To make it even easier, I have some winter sowing worksheets I made for my newsletter family and I’d love for you to have them! These sheets are specifically for winter sowing herbs, but you can use them to get started growing pretty much any seeds outdoors. Once you sign up, they sheets should show up in your inbox (plus you’ll get access to our extensive Member Library).
Preparing the Containers
Starting seeds outdoors in containers is a super simple process, so don’t overthink this or stress out. Here are the steps to prepare your containers for seed starting:
- Gather any opaque or clear container that has a lid. Gallon milk jugs are commonly upcycled for this purpose, though they’re not the most convenient option, in my opinion. I purchased shoe box-sized plastic boxes at the dollar store and they’ve lasted three years so far (with a few casualties due to hail). It’s important that light be able to penetrate the container.
- Next, make small holes for drainage in the bottom of the container, as well as rain penetration holes in the lid. The holes in the lid also allow warm air to escape in sunny weather. In essence, you’re creating a mini-greenhouse and you do not want to cook your baby plants.
- You can use a drill for this or even a wood burner to melt the plastic in round holes. These holes should be sprinkled evenly to allow rain to enter from the lid and excess water to drain out from the bottom. This step is critical.
Planting Seeds Outdoors in the Containers
Getting the soil into the containers is the fun part and getting the seeds into that soil is the most fun of all!
- Put your favorite potting soil mix into the containers and fill them at least halfway. The potting soil should be damp but not sopping. Pre-moisten the potting soil in a wheelbarrow or bucket to ensure that it’s evenly damp. If you squeeze some of the soil in your hand and water runs down your arm, it’s too wet. Add some more soil until it looks like chocolate cake batter.
- Plant the seeds into the containers according to package directions for depth. Be sure to note which seeds need to remain on the surface of the soil for light germination (like chamomile).
- Place the lids on the containers and put them in a dedicated spot for them to sit undisturbed until they begin to germinate and require potting up. You can do this roughly December through August in most temperate growing zones.
- Once the seeds have germinated and developed their first set of true leaves, they are just like any other seedling. Pot them up or plant them directly into the garden.
Troubleshooting Your Winter Sowing Set Up
Here are some tips for the containers:
- A lot of people use milk jugs, as I mentioned, though I find them cumbersome. However, there are many people who use them successfully, so I encourage you to try them to see if you like them.
- I have plastic boxes that have both opaque lids and non-opaque lids and both work great. Enough light penetrates the sides of the boxes with non-opaque lids for the seeds to germinate.
- Be sure to weigh down your winter sown boxes to prevent the wind from disturbing them. I use t-posts laid across the tops of the boxes because the posts are long and just the right weight. However, rocks or bricks also work.
- I suggest you put a layer of cardboard and wood chips under your winter sown boxes to prevent them from becoming soggy and saturated in a large rain event. Any medium that will provide good drainage under the boxes will work. Some people place their winter sown boxes on decks or even outdoor shelves and that works fine. I’ve found that in my climate and perhaps suiting my personal tastes, my winter sown boxes perform better when connected to the earth – sitting right on top of the turf.
- Do NOT let the soil of your winter sown boxes dry out, even while it’s still cold. This isn’t usually a problem during the winter if you have precipitation, but as spring advances, check your boxes regularly. Warmer weather can dry them out quickly and this spells death for the seedlings.
Placement of the Containers and Seed Germination
- Because my spring weather is variable and I get warm days followed by cold days, as well as lots of moisture, I sprinkle the surface of my potting soil with cinnamon as a deterrent to damping off disease and any other fungus that might be in the soil.
- Again, because my weather is variable, I put my winter sown seeds on the north side of my house to discourage them from sprouting too early in the season. An extra early sprout can be damaged by excessive frosts that might follow. My spring weather is very mercurial!
- Some days are so warm that it’s necessary to remove the lids entirely so as not to cook the seedlings. On the north side of my house, I only need to do this rarely. It’s usually about the time that the seedlings have gotten so tall that they need lids off all the time so they can continue to grow. I know it’s about time to plant them in the garden when they get that tall!
Frequently Asked Questions About Starting Seeds Outdoors
Here’s a FAQ section on outdoor seed starting that will be helpful as you get started. I asked all these same questions when I started, too!
How Early Can I Start Seeds Outdoors in Containers?
I put away Christmas decorations the first week of January and get started planting my seeds in their containers to place them outside in the ice, or snow, or rain, or sleet, or whatever is happening with the weather.
You can start seeds outdoors in containers basically anytime up until the end of your growing season, from winter to spring to summer to fall. Seeds are genetically wired to know exactly when to sprout. They take their cues from the weather – sun, day length, rainfall, temperature, etc. So, they may freeze, but this won’t hurt the seeds – in fact, the cold is like a clock ticking, winding down to germination time.
The seeds will sprout when they’re ready and grow up until they reach transplant stage. Make sure you remove the lid of the box once the seedlings reach the top to allow them to grow taller and stronger.
What Kinds of Seeds Can Be Started Outdoors?
The only kind of plants that don’t respond well to cold weather outdoor planting in containers are tropical plants. You may, however, start tropical seeds outdoor in containers once all danger of frost has passed.
Otherwise – flowers, veggies, herbs, perennials – any seed can be starting in cold weather in containers outdoors.
Nope, not kidding.
What If I Start My Seeds and a Late Frost Comes?
It does sometimes happen that the weather will warm enough to germinate the seeds you’ve planted and then along comes a late frost that kills off your baby plants. Here’s what to do if this happens:
- You can always plant another round of seeds, don’t even worry about it. Follow the same process and wait for them to grow. They will.
- Double check to see if you had some of the seedlings survive. These are super strong plants, so be sure to save seeds from them.
- Let the box stay where it is and see if any of the seeds germinate later. Some seeds are simply “late bloomers” and this can work to their advantage in this scenario.
Is is OK to Start Seeds Outdoors?
It’s more than ok to start seeds outdoors; it’s actually my preferred method now! There are two different ways you can do it.
You can start seed outdoors by planting them directly into the dirt – this method is called “direct sow”. However, unless you remember to water consistently, you may lose your baby seedlings to dehydration and exposure.
A much easier way to start seeds outdoors is to plant them into containers that have drainage holes and lids. As I’ve said, this method is often referred to as “winter sowing” even though it can be done any time of the year.
The containers act like mini-greenhouses for each batch of seed planted inside. They enjoy a safe environment free of digging or scratching animals, a stray foot, or any other catastrophe that might hinder the germination of a new seed.
Is it Better to Start Seeds Indoors or Outdoors?
I prefer to start seed outdoors because:
- The seedlings (baby plants) become naturally acclimated to the weather so there’s no hardening off phase. Hardening off is a term used to describe indoor sown seedlings become gradually accustomed to being outdoors in the weather. It’s a tedious process for the gardener and one I’m happy to leave behind as I transition to all outdoor seed starting.
- The seeds started outdoors are also accustomed to the naturally occurring pathogens and pests in the environment of my garden.
- Starting seeds indoors requires a lot of space (I start everything from seed for the veggie, flower, and herb garden); I’d rather have all of that outside.
- The seedlings started outdoors germinate when they’re ready and naturally progress with the season as it advances.
- If I lose a batch to late frost, I pay attention to which plants survived. These are the plants that I’m sure to save seed from at the end of the year because I know they are more frost tolerant. If I continue to plant and save seed from these special frost-hardy seedlings, I will continue to improve my seed genetics each year.
Can I Start Seeds Outdoors in Containers?
Yes, you really can start seeds outdoors in containers and pretty much any container will do.
You outdoor seed sowing container MUST:
- be sturdy enough to stand up to rain, snow, and wind
- have drainage holes drilled into the bottom
- have a secure lid with drainage holes drilled into it (milk jug sowers use duct tape to secure the top half of their modified seed container to the bottom half)
As I said, I prefer rectangular, shoebox-type boxes with snap on lids. They stack well while I prepare them with soil for planting, are easy to drill holes into with a small bit on my electric driver, and hold up reasonably well in the elements.
How Long Before Seedlings Can go Outside?
I know it seems almost magical that seeds started outside don’t need to be babied but, with winter sown seeds, this isn’t a question you’ll have to ask yourself any longer! You’ll never have to take your seedling outdoors again!
When you start seeds indoors, it’s really important to watch their development closely so that you can begin hardening them off to make room for the next batch of seeds to plant indoors.
When you start seeds outdoors, you don’t have to worry about this phase at all because they’re already outside and completely acclimated to their environment.
Should You Soak Seeds Before Planting Outside?
The purpose of pre-soaking and even pre-sprouting your seeds is usually to speed up the process of seed starting. Some seeds have such dense outer coats that I’m a super lazy gardener and I rarely take the time to soak my seeds. With outdoor sowing, soaking your seeds isn’t really necessary.
If you are truly winter sowing (as in, planting your seed boxes in December, January, February), then you won’t have any need to pre-soak your seeds. These seeds that get planted outside that early go through many cycles of freeze/thaw and wet/drained. This means that the protective enzymes that cover the seeds are sufficiently worn away to enable sprouting.
Even if you plant your boxes in March and April, you won’t need to presoak your seeds.
If, however, you are planting seeds in boxes that you want to sprout quickly and those seeds are particularly hard (like sweet peas), pre-soaking your seeds can speed things along and improve germination.
Learn how to Soak or Sprout Seeds with Northern Homestead.