DIY PVC Pipe Cold Frame

Hey all! Today we’re talking about a super quick and easy garden DIY to help you extend your growing season. I have a post about how to make low tunnels/hoop houses over a raised garden bed. Which is essentially a cold frame.

This method is a bit different and is just another way of extending your growing season by covering your plants, generating a bit of heat, and leveraging the greenhouse affect without a greenhouse! I took the easiest, cheapest approach I could for this tutorial—and included notes on some changes you can make at the end of the post. Enjoy!

Step 1: Measure the space you’ll be covering

I made a PVC pipe cold frame for this bed—so the first thing I did was measure it. The corners of this bed are rounded, so I just took the measurement from the spot where I could make an even rectangle.

Remember that you can always cut more off if the frame ends up being too big, but you can’t add it back on! My frame ended up being too big the first time I took it upstairs to dry fit it, so I just trimmed a bit more off.

Step 2: Cut & assemble pipes for the main frame

I used a hand-held PVC pip cutter to cut my 1/2″ pipe pieces down to size. This is one of those tools that I use maybe once a year…but when I do need it, I’m super glad I have it!

Also, I went with 1/2″ PVC pipe for this frame because it’s a relatively small bed, so I was comfortable with how sturdy 1/2″ would be. You may want to use a thicker pipe for larger beds—but the thinner stuff shaves a few bucks off!

After I cut the pieces, I popped them into the 90-degree elbow joints. When you buy these joints, make sure you get elbow joints with slips on all openings, not treads. Slips basically just means it is completely open—you can shove another 1/2″ pipe in there for a snug fit. If the opening is threaded, you won’t be able to fit the 1/2″ pipe in.

Make sure the third opening is pointed down. Then take it to your bed or planting area to make sure it fits as you’d like. Trim any ends if you need to shrink it down a bit.

Step 3: Cut & add legs/stakes

After I was confident I had the right size for the main frame, I took measurements for the legs/stakes. I wanted the legs to go down several inches into the soil to ensure it was sturdy, so I took that into consideration when cutting the legs.

Then I added pipe caps to the ends of the legs. This is an optional step—I just didn’t want to have to clean out soil that got all stuck inside the pipes when I store this for the spring and summer.

Step 4: Clip plastic in place

And finally I draped the plastic over the frame to create my cold frame. I used metal pipe clips specifically designed for this purpose, clipping around the top of the frame first. Then I clipped around the perimeter of the bed, folding the sides into place and clipping them tight.

If you don’t want to buy clips, you can cut the plastic long enough that it reaches the ground plus a few inches. Then you can hold it in place using pavers or rocks. But this option means you need to waste more plastic. Totally your call!

Final tips & thoughts…

It’s mid-February here, and I don’t expect we’re out of the woods with snow yet. If we do get any snow, I’ll go out and brush it off the top of the plastic so it doesn’t get too heavy. This is what I do with my low tunnels.

If you build a bigger pipe frame, I would recommend considering adding a middle support pipe using two T joints and another pipe to help stabilize things. Also, if you want to reuse this same setup again next season, you could consider poking a few small holes in the plastic on the top so that water can drain in and essentially irrigate the bed for you.

You can also choose to build two frames—a top and a bottom—and connect them with the four vertical pieces. That was my first choice, but when I saw how pricey the 90-degree joints were…I decided to revise my plan! The approach I used in this tutorial uses fewer pipe pieces and connectors, keeping the costs down. Happy building!

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