Here is the best DIY mini hoop house I have built yet. I've crafted bunch mini greenhouses and cold frames, taken that info, and made this mini hoop house for my raised bed vegetable garden.
So, why build a DIY mini hoop house? The big answer is that it extends your growing season. You can start seeds earlier in the spring, and grow vegetable later into fall and even winter if you do it right.
I've built and made videos about each of the mini hoop house builds I've done. And with every build, I've learned some more about how to build them.
These season extending rigs are also called a mini greenhouse. I've built mine to fit on top of a raised vegetable bed. AND I've added a major upgrade to make it easier to lift and open the mini hoop house as it sits on the raised bed.
I've had hoop houses slip off the raised bed with high winds, or when you open it, so I crafted a simple solution for that, read below for the details.
Building The Raised Bed DIY Mini Hoop House
I used scrap lumber I had around. I'm all about use what you got. So we had these 2x4s. The mini hoop house sits right on top of the wood sides of the bed. Make your hoop house frame the width of your bed, and however long you want it. Mine is 8' long. Build the frame so that the long ends of the hoop house sits right on top of your bed, not inside the bed sitting on the soil. This will make it easier to open and close, and it will last longer.
For brackets to hold the wood frame together, I think these metal shelf hangers work great. I salvaged mine from some shelves a neighbor was throwing out. These brackets will last longer than the wood they are holding together. And it is completely fine to use coarse drywall screws to connect them. The screws will last longer than the wood as well.
Some tools and supplies:
- Flip Bit https://amzn.to/2yRrHWY
- Automatic vent https://amzn.to/2JTKROf
- UV Outdoor Rated Plastic Sheeting https://amzn.to/2KzYGlg
I've used ¾" pvc for the hoop. Use a tape measure to determine how high you want the top of the DIY mini hoop house to be. You can also experiment with a piece of PVC to see how tight of a bend you can do with it.
I was able to take an 8' piece of ¾" PVC and bend it to fit within the 4' width of the hoop house frame. The peak of the hoop house is 40" high. I have found a higher peak with steeper sides really helps winter snow slide off the mini greenhouse.
I slid in one of the bent PVC pipes at the very end of the frame. I then placed a 4'x4' piece of plywood behind the pipe and drew the arc of the hoop onto the plywood and cut it out. It is best to use outdoor rated plywood for this project. If you can't find or afford outdoor rated plywood, paint whatever wood you are using with outdoor paint after you cut it but before you assemble it. 
These automatic thermatic vents are brilliant for a DIY mini hoop house. The vents open and close around 50ºF, and they are adjustable. Do not buy the cheap ones, they will stop working. For this design, I place one high, to let out hot air, and one low, to let in cooler air. I may add two more of these automatic vents, so each end has two of them. When you get a really warm day in spring or fall, the hoop house can heat up right quick.
Use UV rated plastic to cover your greenhouse. If you use inexpensive plastic, you will be replacing it in a few years. And the plastic breaks and splits apart and gets all over your garden. No fun.
I put in a long 1x2 to support the top of the arch. I drill a pilot hole through each pipe and screw the arch into the cross support. I then cover each screw head and the plywood ends with recycled hose so the plastic is not cut open by the sharp edges of the screw heads or plywood ends.
I attached the mini greenhouse to the raised bed with two recycled hinges. Make sure the hinges you use have a removable hinge pin, so you can just slide out the pin to remove the hoop house from the raised bed edge. If not, you can just remove the screws to disconnect the frame from the bed.
This hinge improvement makes the hoop house green house much more stable on top of the raised bed. It wont blow off in a storm. Learn from me...
A metal handle from my box of salvaged hardware makes it much easier to lift the DIY mini hoop house, and makes it easy to prop open. Note how the rig sits nice on the other side of the bed because of the two hinges.
Watch More Of My Hoop House Builds: