Low Tunnel Guide: Selecting + Setting Up Low Tunnels to Spring Ahead

If I could propel each of your growing seasons, it would be with this modular system: setting up low tunnels in fall. This has a positive, cascading effect across your entire growing season. And it’s something that is much, much easier to do before the ground freezes.

If you’re in a warmer zone than me -- chances are high many of you are! -- this post is coming with plenty of time to implement. For all zones, this task can be completed in the coming month or so. If you’re in zone 4 or colder zone, the drop-dead date would be pre-Thanksgiving (last Thursday in November, to my international friends). 

We use the same EMT conduit to cover our blueberries (bottom of image) to protect against birds, which has seemed to become a growing issue alongside the drought. For those tunnels, we have added an extra 12” to both sides (to make it 12’ total length with a female-female connector to make them high enough for the taller plants.

The only thing you need to do this fall is set the frames up. Don’t wrap the beds in plastic just yet – that comes much later. We want the rain and snow to soak into the beds for as long as possible this winter before covering them, and honestly, you’ll just end up needing to shake snow off the tunnels in January and February if you put it up now, so you’re saving yourself a lot of extra work by waiting. And adding some of the best irrigation to your beds in the meantime.

You can see how when we had in-ground beds, we set them up right at the edge of the side of the beds. We often used snow to heel in the sides, especially the north side of the tunnels until the snow melted. Worked great!

If you’re using PVC, which is easiest, fastest, and more economical in the short-term to setup (but not as long-lived), the most critical task is to pound the rebar into the ground before it freezes. I share more about that in the video below.

Though if you’re making that effort, bending the PVC pipe into place will take all but another few minutes. And while you’re out there, zip-tie together the cross brace too. You are literally framing these in, but not finishing the build until late winter.

A Tale of Four Tunnels

Your garden, your rules. This is a mantra I live by.

I show you how we do things, you take inspiration and either follow suit or riff off what we’re doing.

I am showing you how to setup low tunnels a few ways with either PVC or metal conduit (called EMT, electrical metal tubing) - or even just some lightweight metal for a more temporary system.

You can install the more sturdy PVC or EMT low tunnels one of three ways:

Our original, raised bed garden in south Minneapolis circa 2008. How cute was this front yard?! We used to do a single leader for tomatoes back then, and as you can see all our tall crops are positioned on the north side of the beds.

1.     Secured to the outside of your raised bed with 2 straps (for holding the bent pipe or pvc in place). Side note: this was how we originally did it back in 2006.

Spring 2023: we trialed the added parachute cord to help hold down the plastic. We did switch to greenhouse poly in 2022. It’s clearer and thus lets more light in, but it still does tear though not quite as easily as painter’s poly.

2.     Secured to the inside of the raised bed with sleeves for the pipe to go into. (This is how we are currently doing it)

Our OG low tunnels were PVC, rebar, and 6 mil poly from home depot — plus extra large binder clips and some bricks to hold it all down.

3.     Secured to the ground on the outside of the raised bed OR directly into the ground for in-ground beds (this is how we used to do it here before we transitioned to raised beds.)

Lastly, you sometimes see me using these smaller, more mobile low tunnels. We call them wickets, but I think they are actually known as low tunnels too. Made of #10-gauge corrosion resistant galvanized steel wire, they work well with 84” Agribon and are a much lower profile for seedlings or just seeded areas.

They are not as strong or durable as PVC or EMT, and shouldn’t be used for any type of winter covering. I use them for spring frosts, summer heat waves, and those inevitable early fall plunges that are sudden and short-lived (to eek out another few weeks with my greens).

I don’t ever use these for tomatoes or peppers, but do use them for insect netting on young brassicas and will also use them for shade cloth in summer, as well as if I want to go crazy and DOUBLE COVER things in a low tunnel. This is pretty rare for me, but I have done it in the past, where I had some late lettuce I was trying to keep for as long as possible. If I had the right crops, I could see this happening again in the future.

As a general rule, I prefer to use the lowest tunnels in spring and summer more than fall. And that’s because the fabric will freeze and stick to not only the soil but also to the bricks we use to hold it down. It’s definitely not a perfect system, but we got them for like $.25 each from a friend who was selling her organic farm and everything in it.

As you can see, we try different ways of doing things. Often.

And honestly there’s no perfect system.

With climate change I have found our tried and true ways no longer serve us and we continue to work to refine our system. What worked for us back in our city gardening days didn’t end up translating out here in large part because of our mowed paths, our desire for a super clean aesthetic (we didn’t want the clamps to be visible on the outside of the beds), and because our climate is getting windier. The tunnels and how we secured them has had to continue to change to adjust to our changing climate.

Materials

Raised Bed Low Tunnels with metal conduit:

• 4 ½” EMT metal piping (10’ lengths)

• 12, 1” One-hole straps (can buy in small bags or larger boxes)

• Pipe cutter to cut the cross brace

• 12 1” outdoor decking screws and possibly 12 washers for straps (our screw heads were too small for the clamps and they have fallen off)

• 6, One-inch PVC cut to 6” lengths (for receiving the metal conduit)

• 3 1” Cross connectors (one for each hoop)

• Low tunnel pipe bender (Not an affiliate link — be sure to order the right size for your beds - we ordered the 4’ wide one) 

In-Ground Low Tunnels:

• 12” long rebar (comes in 8’ lengths from home improvement store)

• Angle grinder to cut rebar

• Either PVC (schedule 40) or metal conduit (if metal conduit, you need the pipe bender listed above)

• Hammer

• Zip ties (for pvc cross-bracing)

• Cross-connectors (for metal conduit cross bracing)

For late winter:

• Poly (either 6 mil painter’s plastic or greenhouse plastic)

• ½” snap clamps for metal conduit

• ¾” snap clamps for PVC  

For Lightweight, Temporary Low Tunnels:

• Low tunnel hoops, like these from Johnny’s (not an affiliate)

• Agribon or other fabric (84”

Parts you’ll need for metal conduit hoops if you want to follow how we installed them. You can drop the pvc slip inside the straps if you attach them to the outside of your beds instead of the inside.

I’ve added a Low Tunnels idea list to my amazon page (affiliate link) so you know what clamps, straps, and cross connectors to look for. The cross connectors are an online purchase (I bought mine via amazon) but the rest is readily available at your nearest big box home improvement store or possibly local hardware store. The snap clamps I’ve bought both on amazon and from Johnny’s Seeds.

Here’s an 8-minute video about how we set these up. I go into more detail in this video, so it’s worth a watch.

I sure hope you’ll consider adding low tunnels to your garden if you’re not already using them. They really do help me weather late winter with more grace than I knew was possible.