How to Build an Inexpensive Cold Frame in Under 30 Minutes With No Tools

For over ten years I have grown my own garden transplants by carrying the seed trays out into the sun on warm days and bringing them in every evening. In the last 3 years, I was juggling over 20 trays in and out of the house. This method uses natural light to produce strong, non-leggy transplants — but if you’re growing lots of seedlings it is excessively laborious!

It had to stop! However, my husband and I do not have impressive construction skills. When a friend from Pecandale Farmstead gave us some old windows, she also gave us an idea. Straw bales + old windows = instant cold frame.

Photo Caption: Our straw bales varied in length, but most were about 37" long.

The only materials you need are straw bales and some sort of windows. Craiglist or Freecycle are great options for recycled windows. If you happen to get plexiglass or acrylic ones, they are much less likely to shatter.

The only tools needed are hands (but gloves are recommended).

Photo Caption: Although the cold frame itself was constructed in minutes, it took us a bit longer to clean out a site for it.

Choose a site that isn’t very shaded, although it is okay for it to get part sun in the south. The more sun your site gets, the more vigilant you will need to be about ventilating your cold frame on warm, sunny days. On sunny days ranging 35°F to 40°F, open it a crack. Once daytime temps reach 50°F you may need to open it entirely. Cloudy days don’t require as much ventilation.

Unheated cold frames allow you to overwinter plants that are from a zone (or two) warmer than yours. So, someone in zone 6 could overwinter plants that usually live in zone 7 or 8. In zone 8, you’d be growing plants from zones 9 & 10. It’s also a great way to get your seedlings started and ready to plant out by your frost-free date.

Photo Caption: Much better! It's a good idea to put down wet newspapers and mulch or some other weed barrier under your cold frame.

If you’re placing your cold frame on bare soil, weeds will be just as happy about the cozy environment as your transplants and pots. The easiest way to keep from weeding in the wintertime is to put down a barrier to block the germination of weed seeds and wandering roots. A layer of mulch will insulate plants from the cold ground but beware of pests like slugs hiding there.

Photo Caption: It took a little bit of maneuvering to get the straw bale placed to support the windows. We "eyeballed" it -- no measuring required!

You can stack your bales in several ways to make your frame tall or short. Ideally, the plants underneath shouldn’t be so deeply set they can’t reach the sun. If you only plan to do seed trays, make the frames lower or put the trays on top of something to elevate them closer to the light. If you are overwintering taller container plants, make the frames higher.

If there are gaps between the bales, stick extra hay in the cracks to reduce drafts.

Photo Caption: The finished product will hold more trays than I can utilize in my garden. We'll also use it to harden off some of our taller potted plants.

Minutes later and you’re done! Nothing else is necessary to make your cold frame ready for transplants and pots.

If you have very cold weather consider adding extra heating elements such as black water containers (they absorb sun during the day and release it slowly at night) or bubble wrap on the glass for additional insulation.

Photo Caption: Here's how it looks with plants inside. The windows can be slid to the side for ventilation on warm days.

Ventilation is simple: just place a brick under one end of a window to prop it up, slide it partially to the side, or remove it entirely. Be sure the window is secure to avoid crushed transplants or broken glass.

All done!

I can’t tell you how excited I am not to do the seed tray parade every morning and evening for 3 months.

Eliza Lord

I'm a Greenville, SC native (the Appalachian foothills) who wears the hats of Greenville Master Gardener & Upstate Master Naturalist. I love to write about food and sustainability.

39 thoughts on “How to Build an Inexpensive Cold Frame in Under 30 Minutes With No Tools”

  1. Janet, The Queen of Seaford - March 2, 2012 4:18 pm

    Brilliant Eliza! I have seeds I need to get planted! I don’t think I have as many as you….but they do need to get planted just the same!
    Janet, The Queen of Seaford´s last blog post ..Great Nights and Lovely Mornings

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:16 am

      Good luck with them (may the anti-dampening off force be with you).

  2. Anna - March 2, 2012 6:38 pm

    Husband?! I thought he was a boyfriend five or six posts ago. Did you get hitched and not tell us? Or did you just have a spare husband lying around somewhere?
    Anna´s last blog post ..mark: Keeping new born chicks warm

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:17 am

      Haha… yeah I think we were at the fiance stage last time we talked. We skipped straight to married (Oct 8th) and my photos are on another computer so I haven’t done a post about it yet.

      1. Flâneur Gardener
        Twitter: flaneurgarden
        - March 6, 2012 12:46 am


        I’m so jealous! Though considering that I go to my garden every weekend or other, I really have to lay off with the cold-frame plans! (I do, though, currently live alone in an apartment that’s large enough to leave one room unheated, so there will be a suitable temperature for my seedlings, I hope. Then I guess they’ll have to handle the hardening off themselves, perhaps with the help of some plastic coverings.
        Flâneur Gardener´s last blog post ..Pruning Poetry

        1. Sustainahillbilly
          Twitter: appalachianfeet
          - March 6, 2012 1:08 am

          I understand! I think we all want the “next size up.” Every time someone posts about their greenhouse, my yard always seems too small! Someday…
          Sustainahillbilly´s last blog post ..How to Admit When Your Garden Looks Ugly (and Feel Proud)

  3. Donna - March 2, 2012 7:30 pm

    This is a wonderful idea. I saw it done at farms around here, too. It is a quick method for toasty warm plants.
    Donna´s last blog post ..Trees Dressed in Ice

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:17 am

      Yeah, we figured it was even warmer than wood frames!

  4. Mark Willis
    Twitter: marksvegplot
    - March 3, 2012 2:07 am

    In a year or two, when the straw bales need replacing, you can compost your cold-frame too!
    Mark Willis´s last blog post ..SBDS

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:18 am

      Yep! It’s so hard to resist planting mushrooms in them right away!

  5. PlantPostings
    Twitter: plantpostings
    - March 4, 2012 6:46 pm

    Wow, great idea! I think I could do that! I see that the Forsythias are blooming by you–nice!
    PlantPostings´s last blog post ..Garden lessons learned: winter 2011-12

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:18 am

      You definitely could! We always enjoy the forsythias on the property next door.

  6. Casa Mariposa - March 4, 2012 7:54 pm

    This is awesome!! I may do this next winter. I just started seeds inside. Now I have a cool project for the summer – find windows!
    Casa Mariposa´s last blog post ..Seed Starting for Zombies

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 5, 2012 2:19 am

      Good luck on your window search! I hope you find some freebies.

  7. Alistair - March 5, 2012 8:06 am

    What a great idea. I think the hardening off isn’t quite such an ordeal here. We would sow the seeds in early March and bring them on in the greenhouse. If the temp rose too high we would open the windows and doors. We would just start the hardening off process about 10 days before planting into the borders in late May which was a nuisance, but not for such a very long period. October the 8th, well well, that was our day way back in 1966.
    Alistair´s last blog post ..Paeony My Pal Rudy

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - March 6, 2012 12:59 am

      I agree, I think a greenhouse makes hardening off much easier! We are planning to build a passive solar house around some citrus we’re planting, but we don’t have room for a fully heated greenhouse right now.

      Congratulations on your anniversary, an excellent day for one indeed (also happens to be my husband’s brother’s birthday).
      Sustainahillbilly´s last blog post ..How to Admit When Your Garden Looks Ugly (and Feel Proud)

  8. Pingback: Straw Bale Cold Frame « General Lordisimo’s Apocalypse

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  10. Van in Dallas - August 8, 2012 10:21 pm

    The straw must be very insulating. Love it.

  11. Bill Brikiatis
    Twitter: hobby_farmer
    - August 15, 2012 8:25 am

    I never thought of checking Freecycle for old windows you can reuse in the garden. That’s a great idea. The sun gets pretty low in the sky in October and November. Do you have any ideas about how you can angle the windows (and keep them in place) to catch more of the sun’s light?
    Bill Brikiatis´s last blog post ..Saving Green Bean Seeds

  12. elaine - September 1, 2012 7:49 pm

    Gee, Bill, lets look a this logically…if you build your bed longways oriented east->west and build bales higher on north side and only one bale high on south side, with east and west ends packed straw wedged, you should have full sun all day….I ould suggest

  13. Adda - September 1, 2012 8:08 pm

    Do you think you could put apples, potatoes, onions and etc in this to keep over the winter?

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - January 16, 2013 10:16 am

      I think they would get too warm here, but it might work in a colder region.

  14. joy maguire - September 1, 2012 8:39 pm

    I live in michigan. If I make this can it be left out all winter and what about watering

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - January 16, 2013 10:15 am

      I don’t know how well it would work with Michigan weather, but someone recommended a layer of fresh manure with straw on top as the bottom layer to help generate heat. That might make it more durable in cold weather.

  15. Virginia Dimitriou - September 3, 2012 1:48 am

    From rainy old England. In my home town of Halesowen, when a building was pulled down they exposed a house made out of mud and wattle(straw) at the back. Still standing and still being used. Five hundred years old. We have such awful weather here I don’t know whether the bales would just disintergrate left by themselves. More investigation needed I think – bring on the mud mix.Come to think of it – how the heck are those walls still standing.

  16. michael albert - September 11, 2012 9:16 am

    @Bill Brikiatis~
    I built mine with more bales in the back allowing for a slanted window opening. Have had issues with mice wanting to burrow in. That ended when the cats moved in.
    michael albert
    canton, oh.

  17. Arthaey - September 19, 2012 11:39 am

    To make them more attractive (assuming you don’t care for the look of plain strawbales, which you might!), you could plaster the bales the way people making strawbale houses do.
    Arthaey´s last blog post ..Recovering from two calorie-heavy weekends [Flickr]

  18. Krakatau Tour - October 2, 2012 8:41 am

    Wow,its great idea! I think I could do that! I see that the Forsythias are blooming by you–nice!

  19. medicine woman - October 28, 2012 10:29 pm

    If you put fresh manure then a layer of sand under those plants it will keep your coldframe much warmer.This is the way old folks used to do it and they could start seedlings pretty early.Hope this helps.

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - January 16, 2013 10:05 am

      That’s a great idea, thanks!

  20. Wall Flower Studio - January 19, 2013 1:23 pm

    I am so looking forward to creating this in our yard.
    Thanks for such an informative post! Love your site. : )
    Wall Flower Studio´s last blog post ..Happy Halloween! Reflecting on the Harvest and Saving Seeds

    1. Sustainahillbilly
      Twitter: appalachianfeet
      - January 19, 2013 2:28 pm

      I’m glad you like it!

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  22. Gardening In Kansas - February 12, 2014 8:28 am

    What a wonderful idea. Right now I live in a house that gets horrible natural lighting so I am forced to use grow lights. So this would work nicely for me and help save some money on electricity. Though the question I have is understand this will help keep plants and seedlings warm what is a good average temperature to start this? I imagine you still don’t want it to be to cold out.

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  25. j - January 10, 2015 5:20 pm

    a sheet of plastic is easier yet. if you use water inside a makeshift greenhouse, (think milk jugs/55 gal barrels), it’ll keep the temps above freezing.

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