How to Build a Hoop Tunnel

Last week, I decided – albeit, rather last minute – to build hoop tunnels over four of my raised beds. I figured I had time to get it done before our usual first frost date of November 21 or so. Surprise of surprises, the forecast called for temperatures in the 30s last Friday night (and we got our first frost two weeks early on November 2). So, last Friday, my Garden Wilson and I were running to Lowes to get the supplies and build the hoop tunnels to use that night. Thankfully, it was less expensive than I thought and were super easy to build. If you haven’t thought about covering one or more of your raised beds to extend your growing season (or be able to grow a wider variety of crops in the fall and winter), see how easy it really is to do.

These instructions are for raised beds that are 4 ft x 8 ft to 4 ft x 10 ft. The beds I covered are actually 4 ft x 9.5 ft.

HOOP TUNNEL SUPPLIES:

Hoop tunnel supplies

Hoop tunnel supplies

Assuming your bed’s length is between 8 and 10 feet, you will need three hoops per bed. (If your beds are longer, plan a hoop for every 5 to 6 feet; every 3 feet if you live in an area that receives snow. You may need to reinforce with metal mesh if you get lots of snow.)

For each bed, you will need:

  • 3 each 10-foot lengths of 1/2-inch PVC pipe that is 600 psi
  • 1 each 10-foot length of 3/8-inch rebar cut into 6 pieces
  • 4 mil clear plastic sheeting that is 12 feet wide by length of your bed + 10 ft (I bought a box of 12ft x 100ft so I could have sheets of 12 ft x 20 ft)
  • Items to weigh down the sides and ends of the plastic sheeting (I used 10 ft lengths of old decking and bricks)

HOOP TUNNEL CONSTRUCTION:

1. Cut the rebar into six lengths. Each piece should be at least 18 inches long. My Garden Wilson used his Sawzall with a metal blade. Isn’t he muy macho?

Cutting rebar with Sawzall

Cutting rebar with Sawzall

2. Cut the plastic sheeting. We rolled it out and measured it with a tape measure. Technically, I should’ve cut them at 19.5 feet (10 feet longer than my beds), but I cut it at 20 feet for each piece. I also have a 20-foot piece left over for a spare.

3. Bang the rebar into the ground outside your raised bed using a hammer or mallet until it is sticking out of the ground only 6-8 inches. You will need two on each end and two in the middle. (Each hoop will need two pieces of rebar, so the more hoops you have per bed, the more pieces of rebar you’ll need.)

Rebar in the ground outside raised bed

Rebar in the ground outside raised bed

4. Take a piece of PVC pipe and place one end over the rebar until the end touches the ground. Bend the pipe and place the opposite end over the rebar on the other side of the bed to make a hoop. Be sure both ends of the pipe are flush with the ground.

PVC hoops on raised beds

PVC hoops on raised beds

5. Your hoop tunnel has now been constructed. All that’s left is to put the plastic sheeting over the hoops. Center the plastic over the hoops – you will need two people to do it – and anchor the sides with decking or other heavy objects after pulling taut. Pull the front and back ends taut and anchor with bricks or cinder blocks.

Buttoned-up hoop tunnel

Buttoned-up hoop tunnel

That’s it. It took us less than two hours from start to finish to make four hoop tunnels. And the supplies for all of them cost less than $100 at Lowes. How great is that?

IMPORTANT HOOP TUNNEL INFORMATION:

There are certain things you must know about using hoop tunnels so that you won’t kill your plants.

  • Make sure that your plants do not touch the plastic. During a frost or freeze, any leaves or branches touching the plastic will be frost-bitten.
  • You MUST vent your hoop tunnel or remove the plastic altogether during the day. Even at mild temperatures, the sun’s heat can cause the temperature inside your hoop tunnel to rise to 130 degrees! That will cook your plants! On days when the temperature is in the 40s or low 50s (and we’ve had a couple of those), I open up the ends so the air can circulate through the hoop tunnels. When the temperature is going to be higher, I completely remove the plastic when the temperature hits 50 degrees. Where you live and what the temperature is makes a difference. It’s best to get a thermometer that can give you the actual temperature inside the hoop tunnel to determine if venting is sufficient or if you need to remove the plastic for the day.
  • Plastic sheeting will give you 3-6 degrees of frost protection. For 6-18 degrees of frost protection, add one 25-ft string of C7 incandescent (not LED) Christmas lights for every 4-5 feet of bed. For my beds that are 9.5 feet long, I will attach two strings of these Christmas lights lengthwise, which will go down and back four times. The heat from these bulbs will give you additional frost protection.

I’m looking forward to seeing how these work for me, and I’ll be experimenting with growing a few plants that are not normally grown in the fall and winter. I’ll let you know how that goes.

Let me know how hoop tunnels work for you in your neck of the woods.

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2 comments on “How to Build a Hoop Tunnel

  1. Are you planning on constructing any tunnels with row cover fabric? I would be interested in seeing how the fabric compares with plastic. I think there is less danger of “cooking” veggies. I am not sure about the difference in frost protection. I have used both along with sheets and quilts, but never really compared them.
    I found that tying a string across the tops of the hoops helps keep them in place during storms, especially if you extend the ends of the string and anchor them to the ground or the frame of the raised bed.
    In the spring, I replace the covering material with a light weight insect control row cover and plant summer squash. I hand pollinate. The squash I planted in March is still producing!

    • I chose the plastic because I needed it that day! It’s a pain having to remove it/vent it, yes, but at least I’ve got a way to extend my season this year. I do want to get some agri-fabric though – maybe for next year.

      I wish I could cover squash and hand-pollinate regularly, but I had trouble doing it often enough with my winter squash. The flowers open while I’m at work, so I can hand-pollinate only on weekends. Fortunately, much of my winter squash/pumpkins survived the SVB attack and insects took over the pollination.

      I’m actually using a tarp over my key lime trees, along with large Christmas tree lights at the base of the tree in the pot. Seems to be working okay for now. I even have new flower buds forming. Yay!

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