Building a Caterpillar Tunnel
Starting the business, before we could afford permanent greenhouses and high tunnels, we constructed an inexpensive 100ft caterpillar tunnel that could be easily managed and moved.
This tunnel is a great option if you need to protect plants for season extension, but you really don't have a ton of money to spend or have a small space to work with.
What you need:
- 42 2 ft long Rebar
- 21 20ft long PVC or Metal Conduit
- 20 Metal Dog Stakes
- 42 Clamps
- 150 ft Rope (we used clothes line)
- Strong String (we use a heavy grade hay bale twine)
- 2 Earth Ground Anchors
- 2 Heavy Duty Ratchet Straps
- 125 ft Greenhouse Plastic
First map out where you want to place the tunnel. Every 5ft, pound a rebar stake into the ground for 100ft, these are where the poles will be placed. Do this again on the other side making sure there is 12ft in between. If you are using metal conduit, you will need to bend them with a Johnnys Hoop Bender. We used two 10ft pieces and bolted them together, creating your 20ft pole. We like to use fencing top rail that you can easily find at Home Depot or Lowes. They link together, allowing you to drill a hole and place a bolt in the middle where the two join. If you are using PVC, they are easy to bend into the shape, but keep in mind they are not as sturdy. Ours are constantly breaking (mostly because we accidentally hit them with our brush hog, oops!) so we are slowly switching the whole tunnel to metal.
Place the poles over the rebar pipe and bend them to the other side to meet the opposite rebar pipe. Continue this for the whole length of the greenhouse. You can make this caterpillar as long or as short as you'd like. To save money and get the hang of growing in a tunnel, maybe start with a shorter tunnel with less hoops.
Once all the hoops are up, we want to tie them all together with some kind of rope. We used clothes line. Run the rope over each pole the whole length of the tunnel, making a loop around each one. At the each end of the tunnel, tie the rope off to an earth ground anchor.
Now its time to pull the plastic over the hoops. Make sure to do this on a calm day without wind and a few extra hands. Once the plastic is over the hoops, tie down each end of the plastic using a heavy duty ratchet strap and attaching it to the earth ground anchor.
To secure the plastic, set metal dog anchors in between each hoop the entire length of the tunnel. Twine gets tied to the dog anchor and then thrown over to the other side and tied to the dog anchor on that side. Make sure the plastic is nice and tight while tying the the twine.
The tunnel is now complete. Make sure to keep an eye on the inside temperature of the tunnel. If it gets too hot, use plastic clamps to hold the plastic up on the poles for ventilation.
On windy days, make sure to check for tautness and tighten the ratchet strap on each side, if need be.
This tunnel is great for things like heirloom mums. We throw it up quick in early September just to protect the tender buds from getting too cold. We wait until September to put it up with this crop so that we don't have to be constantly watering the tunnel during the hot months of summer. We then take it down after the mums bloom in early November.
If you want to use the tunnel for heat loving crops and keep it up all season, dahlias are a great option. Just remember, this tunnel is not meant to withstand winters, so be sure to take it down before snow flies. It disassembles even easier than it goes up!