Seed seed starting Seedlings - General health wintersown

Adjusting the WinterSown Method to Allow You to Start Vegetable Seedlings without Indoor Lighting

Understand that the “official” or “original” or “real” way of wintersown involves starting seed OUTDOORS in “taped closed” jugs (with the cap off for ventilation). They get the proper light and because of the somewhat protected environment, get off to a earlier start (germinate sooner) than they would if they were sown in borders or gardens without the protection of the container.

The seed of certain plants can be sown in these jugs (or other various containers) and go through extreme low temperatures, germinate, and still go through freezing and thawing cycles many times without harm. The seed will know when it’s safe to come up. That’s how this kind of seed/plant was designed.

Here are a few characteristics to look for that will give you an idea as to whether or not the seed will be successful when subjected to freezing and thawing after germination.

The seed of plants that:

  • need a period of prechilling before they’ll germinate (like snapdragons)
  • self sow in nature (your borders or garden)
  • come up by themselves in the spring
  • are sown by nature (or seed packet instructions) in mid to late summer
  • are sown (by seed packet instructions) before the last frost, like many wildflowers.

Growing Seedlings Inside

If you grow seedlings inside for any length of time, other than to allow them to germinate, you have to have sufficient artificial light. Thus, you need a place for whatever jugs or flats you use, plus a set up of lights to be kept only an inch away from the seedlings. (You don’t need grow lights.  Plain fluorescent lights, warm or cool, will do just fine.)

If you’re a regular reader you already know that I don’t have any space to set up a growing system inside my house.

Modifying the WinterSown Method for Vegetable Seeds

Necessity is the mother of invention and sure enough that is how I came up with a way to start seeds using the “idea” of wintersown.  But I modified it to adapt to the needs of vegetable seeds and seedlings that may not be hardy enough to take freezing temperatures even with a taped closed jug to act somewhat like a mini greenhouse.

How to Get Started

  1. Prepare your containers and identify what seed they’ll hold. (See my post You Can Plant in December) Remember to wet the grow mix well before you plant.
  2. Sow the seed.
  3. Place the jugs inside (I put mine on top of my washing machine; the top of the refrigerator is also a good place). The temperatures where I keep them runs from 58° to 65 ° F this time of year.  A few degrees warmer in a month or so.
  4. Let the seed germinate.
  5. Either immediately or at least within a day or so, tape the jugs closed (take the cap off for air circulation) and place outside. They’ll be hardened off immediately which saves a lot of time.   If you wait too long, you’ll have to go through the hardening off procedure.

Things You Need to Keep in Mind

To be successful with this adaptation, you have to put your thinking hat on and have some idea of what the plant can tolerate and what it can’t BEFORE you start. (Easy to know if you’ve gardened any length of time or just by doing a minute or two of googling.)

In General, Certain Plants Can Withstand Light freezes. Others Can Withstand Hard Freezes.
To have the BEST success it’s important that you know what category the vegetables you’re planting fall into.
Tolerates Light frost/or freeze – Temperatures will range from 28-32°F
Tolerates Hard freeze – Temperatures will be below 28°F

AND the other thing you have to keep in mind when making your decision about what to leave out in colder temperatures is what other variables are involved?

Here’s a few variables to think about:

  • Do you want to take a chance of temperatures going lower than predicted?
  • Are the containers on the ground or off the ground? The ground holds more heat (if it’s been warm) and can impart that heat to the containers on the ground.
  • Some areas outside might be more protected than others. Are your containers in such an area?
  • Will it be windy? In cold windy conditions the warm air even in protected areas can be blown away.
  • Plants growing in warm conditions that experience a sudden drop in temperature that they usually could take, may not survive because the change is so sudden.

Another Point to Consider: How Old Are the Seedlings?

Newer seedlings are more likely to be damaged by a severe temperature change.  Lets take onions for example.  Onions can tolerate very low temperatures.  Temperatures below 20 they don’t like, but they can make it through.

I have small onion seedlings that I started a month ago or more in jug bottoms without the tops. When the blizzard and very low temperatures were in the forecast, I brought them into my enclosed porch and put them back on top of my washing machine during that cold week.   I’ve lost small onion seedlings that way before when only about 10% made it through. I didn’t want to lose these so I brought them in.

The day I put them outside again was really warm, but that evening was in the 20s.  I bundled a large piece of row cover fabric and placed gently over the onions under the cold frame.  Took it off the next day.  Probably won’t be severe enough to be needed again.

Bundled light weight row cover fabric over the seedlings under the cold frame in expectation of temperatures in the 20s that night.

Although there are several vegetables considered cold hardy enough to tolerate temperatures several degrees below freezing, many can be effected adversely in some way. With any vegetable crops consider carefully when temperature are expected to fall between 28° and 32° F. Consider even more carefully when they fall below 28°F.

Warm Weather Crops

In general ALL warm weather crops such as melons, cucumbers, tomatoes, potatoes, peppers, eggplant, corn, squash and beans will be KILLED when temperatures drop to 32°F and below. There are always exceptions especially with well established older plants, but don’t take a chance on leaving young seedlings of these plants out in an expected frost/or freeze.

All grown with a variation of the winter sown method.

Tomato and pepper seedlings. All grown with my variation of the winter sown method.

When I start warm weather crops and then put them outside, they’re in a taped up jug until daytime temperatures stay above 50°F.  If temperatures fall below about 38° I put them under a cold frame for even more protection just to be on the safe side.

TIP: Don’t start warm weather crops too early.  I start thinking about it in March and look over the forecast.  If temperatures are warm I’ll start seed in mid March. If temperatures stay cold, I wait until the end of March or the first of April.

Various Notations on Cool Weather Crops

The cool weather crops I started in January are lettuce and onions.  I’ll be in full swing the first week of February and will sow beets, radishes, chard, spinach, and several other things.

Below, I’ve noted a few vegetables that thrive in the cold BUT keep in mind as you read that variables will have a lot to do with what happens and nothing is written in stone. What I’ve noted is what is generally true.

Broccoli, cabbage, kale, peas, spinach and turnips can take a lot of cold.

Brussel Sprouts do very well in the cold. I have two experimental plants in the garden right now. Both have some degree of protection; one more than the other. The one I could get to looked great after the blizzard. I can hardly wait to see how the larger one faired.

As Ray (friend and reader from Canada) mentioned in a comment to the last post, he has lettuce and beets that look great through the plastic of the tunnels. He can’t get into his tunnels until some of the ice and snow melts. That’s my situation as well.

Kale, carrots, parsley, and peas do well most of the time.

Leeks and spinach are extremely hardy.

Broccoli, cabbage, cauliflower, chard, lettuce, radishes and turnips can do well to about 28 degrees (some lower) – depending on existing variables. Even if they suffer leaf burn at 28 degrees they may still make a comeback.

Lettuce is influenced by variety as well as temperatures.  Sierra Batavia, one of my top favorites, does not like the cold at all.  It protests by declining in vigor immediately at the first 32° F night.  In order to have good lettuce all through cold winters (under protection) you need to have a variety like Winter Density that does well in cold weather.

Final Thoughts

With the information I’ve given you and a little thought, you can be very successful growing from seed without any indoor setup.

If you do lose something, just consider it a lesson learned and keep going forward.  You’ll do very well.


Addendum – PICTURES –  After reading Frank’s comment, I thought it would be helpful to clarify with a picture showing how I cut the jugs.  Although you can cut the top off completely and then tape it back, it’s easier if you don’t cut it completely off.  Leave about an inch connected to act as a hinge, as I’ve indicated in the picture.

Also I’ve shown some onion seedlings that should have gone outside two or three days ago.  Although it’s warm today (60 degrees) – it’s very windy, so I’ll put them under the cold frame for some protection until they adjust.

Hope you’ll find these pictures helpful.

When cutting, you can leave about an inch to act as a hinge connecting top to bottom. Easier that way.

When cutting, you can leave about an inch to act as a hinge connecting top to bottom. Easier that way.


These onion seedling were ready to go outside 2 or 3 days ago. I'll give them some protection under the cold frame until they adjust. (It's going to be very windy today and that would be hard on them without a bit protection since I'm late putting them out.)

These onion seedling were ready to go outside 2 or 3 days ago. I’ll give them some protection under the cold frame until they adjust. (It’s going to be very windy today and that would be hard on them without a bit protection since I’m late putting them out.)

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  • Theresa, I didn’t quite understand what you meant by taped jugs until I studied the bottom photo. You save the tops of the milk jugs and put them back on when needed.
    Great post.

  • This article gives more succinct info and advice for successful gardening than a stack of books. Thank you for sharing your success with us and empowering every gardener to be successful and enjoy their hobby!!!

  • Frank, I’ve added pictures to the post so you can see how I cut the jugs. Sure appreciate your input because it helped me to realize I was not showing enough about cutting the jugs. (Picture worth a 1000 words etc)
    (And by the way, just FYI, my jugs are from distilled water rather than milk.)
    Glad you liked the post!

    I left off the little mark over the “a” in your name because I have not yet figured out how to add it. 🙂
    What a great compliment you’ve given me. Thank you so much. I’m delighted to learn I’ve accomplished my goal.

  • The jugs being on the ground has zero effect on the temperature beneath them. The ground is actually shaded by the jugs and cannot pick up heat and any possible heat cannot be stored in the entire ground–the earth is not a sealed and capped container.

    I have stated the reason why I place jugs on the ground vs a picnic table. The ground can be convenient and it certainly has larger space than a tabletop. However, my dog run around on the ground and I can’t trust them to not destroy a container like a toy. So, they’re not on the ground because in my garden that ground is not safe for them. It has nothing to do with soil temperature because soil temperature under a container does not increase by solarization.

    Also, unless you actually observe it happening you cannot say that tender seedlings cannot take temps below 32 degrees. Simply not true. Perhaps for those started indoors, but certainly not those sprouted outside via WS. I’ve routinely seen tomato seedlings rake frosts down to 27 degrees and not be effected other than purpling of their stems.

    While I do like your information I ask that you relate information based on observation rather than repetition of dogma.

    Thanks and good luck with your Winter Sowing.

    Trudi Davidoff
    WinterSown Educational.

  • Dear Trudi,
    It is a pleasure to have your input and I welcome you to TMG.
    When I first wrote about wintersown back in December of 2011 I mentioned you. Here’s the link:

    Although I’m glad to have your input and certainly welcome it, I have not necessarily found your findings to be the same as mine.

    Also, if you read the post, you will know that I was speaking of vegetable seedlings (warm weather crops in particular) started inside and not those started outside that know when it’s time to come up. This post is not about winter sown, but rather an adaptation of the winter sown method.

    Although I too have seen tomato seedlings in a true winter sown condition brave temperatures in the 20s, I don’t recommend that my readers start tomato seeds in January and put them out in that kind of weather.

    Your statement about ” I ask that you relate information based on observation rather than repetition of dogma.” made me smile and I’m sure it made many of my long time readers smile as well.
    Of the almost 600 posts on TMG, one of the things that I’m known for is telling what I observe and not just repeating what’s out there.

    I wish you good luck with your Winter Sowing as well.

  • Theresa,

    Do you know if the “your choice” tomato seed
    offer is still going to be available?

    I was so happy to see the response from Trudi…I was unable to link to the wintersown website for a while, but it seems to be partially available now.

    We do have a light set up here, but I’m thinking winter sowing Milkweed seed, possibly some perennials as well. Better get a move on!



  • Theresa,

    I already found the answer to my question…there is a new site (being built) and the free seeds with a SASE are no longer being offered.

    I want to thank you again for your wonderful work here. Hope all is well for you.



  • We have days of 30 lows to 85degrees high in the chapparal of Southern California (Pomona Valley) so I have to be careful to water my seedlings well. How do you do it if the containers are taped with the tops open? Do you cut a few holes in the bottom and water slowly from the top?
    Also might the tops “cook” the seedlings on these hot days? I am afraid to use your method. Any wisdom?
    Dan Pearce

  • Hi Daniel,
    Your questions show that you are using brain power and common sense which are the two main requirements for using any method that is subject to nature’s variables.

    I usually have anywhere from 24 to 150 jugs in the spring. I do peek at them from time to time through the top opening to see what’s happening. Out of 100 jugs I might find 4 or 5 that dry out. My grow mix is a depth of about 3 inches and is saturated but drained BEFORE I add it to the jug and then plant. The tops (along with the depth and pre-saturation) seem to hold that moisture just fine except for the occasional one. When one is dry, I usually pull up enough tape to allow me to get into the jug and water until the mix is saturated again. (The drainage holes in the bottom prevent it from staying too wet.)

    Every once in while I water slowly from the top (where the cap was) but if the mixture is totally dry that is not the best way.

    I am in question about what you meant when you said “Do you cut a few holds in the bottom–?”
    It is absolutely IMPERATIVE that you have drainage holes in the bottom of the jug BEFORE you plant. You need moisture in the grow mix but not something that is slushy wet. So you need drainage holes.

    It you’ve read all the information on preparing the jugs (I’ve gone over that in many seed starting posts) you already know that. So I’m not just sure what that question is referring to.

    And yes of course, in full sun at 85 degrees the seedlings might cook. I start keeping a close eye on my seedlings when we start getting sunny 60 degree days. They’re usually fine, but as the temperatures climb to 70 and above they might need shade at the least or the tops loosened.

    You could possibly remove the tape on your jugs to allow opening in the daytime and loosely reset them at night to protect from below freezing temperatures.

    Please let me know if I have answered your questions.
    Also I think you are wise to think things through FIRST before you use any new way of doing things. Please let me know how you are doing things now. I would be very interested and it will help me to help you (and others) more.

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