Build a Low Tunnel to Protect Your Plants

Low Tunnel

There will sure come a time when you’ll want to get a jump start on the growing season or extend the existing one. This can be tricky, but there are some effective ways on how to do it. One of the best methods are the so-called “low tunnels”.

Low tunnels are made to protect your plants from the frost. They are very effective when it comes to shielding your plants from frost and cold. The best thing is that you can make your own, homemade low tunnels relatively easily and without much cost. A low tunnel is a simple structure but it’s very effective and it will help you start your plants early or grow them during the winter.

Before you start building your low tunnel, you need to learn about the difference between frost and freeze and how to protect your plants from both. You will also need some materials, such as Christmas lights, PVC pipes and water bottles, but most of them are either cheap or something you can easily find in your own home.

An Introduction to Low Tunnels

Low tunnels (along with row covers and hoop houses) are a great way to protect your plants from the frost, so you should definitely consider using them.

The most important part of a low tunnel is a floating row cover. It’s provides protection form the frost. Row covers are typically made of various lightweight fabrics. They “float” on top of your crops, protecting them but also allowing enough space for sunlight, air and water to pass through. This way, the plants are protected but also receive all the light, air and water they need.

These row covers are very effective and you can make them even better by building simple row tunnels. Low tunnels give you easy access to the crops while also protecting your plants from the frost.

The basic structure is easy: you simply need to stretch a row cover over a frame (made of semicircular hoops). It’s important to note that the support of the hoops will also keep the weight of the snow away from your plants. It also allows you to easily lift the row cover when you want to harvest.

Low Tunnel

Building a Low Tunnel

Building a low tunnel for your garden is not complicated and even beginners can do it. The frame (supporting structure) is the most important. Typically, a low tunnel is made to accommodate a bed that’s 3 to 5 feet wide, but you can adjust the design to suit your own needs.

Materials (per each 5 feet of tunnel):

  • 2 18” pieces of 1/2” rebar
  • 1 7 ft. length of 3/4” PVC


Pound the rebar into the ground and make sure that it hits the angle of about 35-45° toward the center of the bed. It’s important to save about 6 inches of rebar sticking out of the ground. They will make the base for your structure.

In case you want to leave the rebar in the ground after you remove the low tunnel in the spring and summer, it’s best to paint its tops a bright color or flag it. You need to do it so they won’t become a tripping hazard.

To create a hoop, simply slide a 7-foot length of PVC over the rebar. Repeat this step down the bed every 5 feet.

This is how you make the basic structure of your low tunnel frame. The next step is to fit floating row cover over your low tunnel frame. To do this, you will need following materials:

  • 1 piece of ¾ inches PVC pipe in the same length as your bed
  • 1 piece 83″ width x 50′ long AG-30 Agribon (add 4′ extra for each end)
  • 2 times ¾ inches rowcover clamps (per each 5 feet of tunnel)

To make a sleeve, cut a piece of Afribon off the roll. Make sure it’s about 8 feet longer than the length of the bed. This will allow the fabric to drape over, closing each end of the tunnel. This is important for providing protection to your plants.

The next thing you need to ensure is that it’s easy to vent the tunnel and harvest the crops. This is why you should sew a simple “sleeve” down one of the long sides of the Agribon. To do it easily, it’s best to take about 6 inches of the fabric along the long edge. Fold it over and simply stitch it in place.

The next step is to drape the Agribon over the hoops. Carefully, slide your long piece of PVC down the sleeve. In case you didn’t sew a sleeve, use more of the ¾ inch clamps to secure this long piece of PVC to the edge of the Agribon. After this, gather and secure the fabric at the each end of the tunnel with a rock or a sand bag.

This way, you will be able to easily lift one side of the fabric to vent the tunnel or to harvest your winter vegetables.

How to Use the Tunnel?

Once you have your low tunnel in place, you need to know how to use it. The best way is to use it to extend your growing seasons at both ends of the year. In other words, you can use it both to get the jump start of the season in late winter and early spring, and to prolong the season in late fall and early to mid winter. This way, you will be able to grow many different plants (particularly vegetables) to a great success.

For example, you can plant various cool-season crops in late summer and you can continue to harvest them well into winter. You can use the low tunnels to warm the soil in late winter and early spring so you can get a jump start on the growing season. This way, you will be able to grow cool season vegetables that prefer spring and fall weather.

Photo credit: Chiot’s Run via photopin cc