Cold Frame Idea

OH has done some amazing cold frames. I'm sure he'll have some great feedback.

Am I right to assume the CF is on the south side of the bed? Is the drawing to scale? That is, will you be able to reach the plants on the CF side of the bed during the growing season?

Happy Gardening!

Hi! The drawing is not to scale  Basically the cold frame would be able 6 feet in length and and 26 inch in width. The planter would be the same length and 24 inch wide (so basically it would be a 2x6 ft mini raised bed which would give me another 12 square feet to do more SFG).

I like it, as long as you can get into all of your squares.

I would be able to get into all my squares with it being overall a 4x6 structure just divided around the middle. I was just unsure about whether or not the 2x6 mini raised bed side would effect the cold frames ability to stay insulated if that makes sense. My goal would be to then add a small garden tunnel (poly tunnel) on top of the 2x6 mini raised bed side to both extend my growing season and/or to have spot that I can grow kale (or other brassicas) with netting over the summer to keep the cabbage worms at bay. I hope this is making sense...LOL

Jam, the most important thing about the cold frame is the angle, or slope of the top of the cold frame. The winter angle of the sun in your latitude determines the angle of the top.  To get the proper angle, add 15 to 20 degrees to your latitude to get the correct angle.  I don't know what your latitude is, but as an example I am at latitude 39.76º, so the top of my cold frames need to be between 54.76º and 59.76º.  Adjust that for your area.

The best cold frame size I have found is 3' by 6' long. The 3' depth allows me to reach the entire inside area. Ensure it is high enough on the back side to grow your desired plants.  For example, I raise Swiss Chard along the back side, with Spinach in the middle, and Leaf Lettuce in front. They all fit within the height at those locations. 

If you get an extremely cold period, put a 100 watt incandescent light in the cold frame to prevent freezing.  I keep a digital high/low thermometer in mine just because I am the curious sort of person.

Where I live, we rarely get below 25*F and most of the winter crops don't need a covered frame. But, I have PVC gable-roof frames on all my beds except the tall trellis beds. If we get a hard freeze I can cover with pre-cut and labeled 4 mil plastic sheeting.

Old-fashion Christmas lights work for most of the hard freezes. One year I added a bed-side lamp with a 100 watt incandescent bulb and it was downright toasty. Too toasty if I didn't uncover by 7 am when the sun peaked over the neighbor's roof!

JAM23 wrote:26 inch in width.

Is 26 inches the width of your window? The main complication I see is that, factoring in OG's suggested slant, that the north bed might be slightly shaded on it's south side by the cold frame. You could compensate for this by making the north bed higher.

For instance, if you live in mid-Illinois at around latitude 40, and used 20 degrees as the adjustment angle, then the back wall of the cold frame would need to be 26 * sin(20+40) = 22 inches. So a 6" high south garden would have a 22 inch sun-block in front of it. You could make the north bed 16" higher, and then this wouldn't matter. But I don't know if your landscape/plans allow for that. The blockage is less if you use the lower number of 15 degrees and if you live in Southern Illinoise (Il. varies by 5.5 degrees North/South).

This is my 4x4 cold frame.  2 doors with a 20 x48” sheet of quarter inch acrylic.  High side is the north end.

Thank you all soooooo much for all this great information. I did read up on having a slope and I figured my north bed would have to be as high as the tallest point of the slope. I am going to spend some time this summer figuring out the best place to put this in my yard. My backyard during the summer gets about 5-6 hours of direct sun with a bit more when there are no leaves on our trees (spring/fall). I just want to make sure that I get enough sun to make this a successful endeavor. I also know that I want to make sure that it's near a water source and somewhat close to the house. 

You guys really are the best group!

Can't believe it is almost time to get the cold frame set up, and the winter lettuce and spinach planted in it. Beginning to wish I had a bigger cold frame that I could grow some Swiss Chard and Kale in, but maybe next year....

Meanwhile, Dave's Garden has a good article on extending the growing season with a cold frame that some may find interesting:

Stretch the Season with Cold Frame Gardening and Greenhouses

With 90F temperatures, I could really use a cold frame right now. So could my plants.

markqz wrote:With 90F temperatures, I could really use a cold frame right now. So could my plants.

Seeds 'N Such has a very good article in their blog on "The Magic of Cold Frames", which is an excellent article for this time of the year when we are trying to extend our growing season.  Check it out here:
https://seedsnsuch.com/blogs/gardeners-greenroom/the-magic-of-cold-frames-extending-your-gardening-season-with-a-diy-box

Thought of the day: Why do they call it a cold frame, when it keeps things warm?

markqz wrote:Thought of the day: Why do they call it a cold frame, when it keeps things  warm?

Actually, a cold frame does not keep plants warm, it only shelters them from the harsher elements of the early or late weeks of the growing season.  To grow plants that require warmth, one must have hotbed, aka a hot frame.  I have used a hybrid of the two -- I dug down into the soil, added some fresh manure to the hole, refilled the soil, and put a cold frame over it. Gave me a warmer frame.

A hot house has supplemental heating, correct, to bring the temps up the tomato temperatures?