I’ve been thinking about ways we can extend our growing season. Why wait to plant in May when we can plant lettuce and other cold weather crops in March? And what about harvesting kale and Brussel sprouts in December or January? So I started building these cold frames that fit over the raised beds. They can be removed in the summer and are sturdy enough to weather the spring winds or the winter snows we get here in Iowa. And they’re easy to build.
Here’s what you’ll need to build one frame:
- 3 – Pressure Treated 2x4x8
- 4 – 1/2in PVC in 10ft lengths
- 1 – Roll of 6mil 10x25ft painter’s plastic
- 1/2in brackets, outdoor treated screws and a staple gun
- 2 hours of time
First of all, its important to have good help when building these frames. I have a little boy who loves to work outside, and he was my shadow the whole time during this project.
I built our frames to match the raised beds I built earlier last month. These measure 40in wide by 8ft long. Cut your 2x4s to match dimensions of whatever sized bed you’re using. The frame is built with simple butt joints and it should be independent from your raised bed box so that you can remove the cold frame when needed. After securing the joints with outdoor screws, I reinforced the corners with 90 degree steel angle bars to take out the flexibility in the frame and relieve the stress on the joints when moving it.
After the wooden frame is secure, line out your PVC pipe. I wanted my frames to be tall enough to house anything we wanted to plant in the box, so I used 10ft pieces. This should give us enough room for kale or even late season tomatoes.
Measure out where you want your PVC. For a basic hoop frame, 4 should be enough to support the plastic, but if you’re building a longer frame you might use more. Here I used 1/2 inch brackets to support the bottom of the PVC.
I then used a second 1/2 bracket to keep the PVC from slipping. You can also screw the PVC directly in to the wood, but I found the two brackets worked nice when it was time to bend the PVC.
Here’s where that extra hand comes in handy. Bend the PVC into a hoop and attach with a 1/2 bracket on the other side of the frame. After all four pipes are secured you’re hoop frame should look like the skeleton of a covered wagon.
You have some flexibility on which kind of plastic you use to cover your frame. No need to spend a lot of money here. I used 6mil painter’s plastic because I wanted it to hold up against the elements. But you could easily use cheaper 3-4mil plastic as well. The thicker stuff isn’t going to create much more heat inside the frame compared to the lower grade. I just didn’t want to have to change the plastic every year.
A good heavy-duty staple gun will shine here. You want to get the plastic centered and then staple to the frame. An added bonus of a hoop frame is that is doubles as a shelter that can potentially keep some of those bugs out. I staple along the outer frame, and then tucked the plastic underneath and staple again on the inside. After attaching both sides, tuck the flaps on the ends tightly over, like you would when wrapping Christmas presents, and then attach. Cut off any extra plastic so it doesn’t interfere with crops inside the frame.
There are tremendous benefits to having a few raised hoop houses like this. They create a safe haven for those transplants you’ve started from seed indoors. They give you the ability to sow seeds directly outdoors earlier in the season, even when the ground temps are still well below 60 degrees. And they can allow you to extend your growing season into late fall or even through the winter months. And I like the flexibility of being able to take these hoop frame off and move them around based on our growing or rotation needs.
So what did we plant?
We let the soil rest for a week underneath the hoop frame before planting this weekend. We’re experimenting with seeds strips, which are seeds placed in strips of biodegradable cloth (a very cool option for so many reasons!), and I thought the hoop frame was the perfect place to do that. The picture above shows lettuce and spinach placed in alternate strips. These will be harvested as a “baby” crop for a tender salad mix, so I’ve intentionally placed them close to each other to maximize space. I’ve also sown Siberian kale seeds in short rows at each end of the bed. These will all be harvested in about 25-30 days, and then followed by a successive crop of peas.
Wanna build a hoop frame? Let us know what you think. We’ll be posting more pics on how these hoop frames can be used on our Facebook page and on Instagram. Follow us if you aren’t already and share your own pics if you decide to build one.