Without fail, the “Spring of deception” gets me every year. Do you have one of those where you live? That’s become the name for the period of warm weather we always tend to get right around mid march in Georgia. It tricks you into thinking spring has arrived. Then, right as you get excited for spring, a cold front comes through to remind you that you still have a month til that last frost date. It can really sneak up on you and damage plants if you’re not prepared. I’ve learned my lesson growing ranunculus, and set up a raised bed garden cover to keep my plants protected. It’s super easy and quick to set up. So, I’ve put together this quick tutorial to show you how to set up your own, too!
Different frost protection methods
First, let’s review your option for frost protection. The quickest, most basic way to protect plants from frost is to just throw a sheet over your plants for the night. I might do this in a pinch. However, this is not great for delicate plants as the unsupported weight of the sheet could weigh down the plant stems and cause damage. As a slight upgrade to this method, you can add supports underneath the sheet by using tomato cages, mixing bowls, small trash cans, or whatever you can grab in a hurry. Alternatively, you can cover individual plants with plastic jugs or bottles with the bottoms cut off, as seen here.
The problem with these quick and easy solutions is that you still have to clean everything up the next morning. While it’s not a ton of materials to put away, it is a bit of a hassle. The set up and take down each time can get old. I prefer using frost protection that I can leave outside as long as I need it, but that I can still remove when warm weather arrives. That brings me to frost tunnels.
What is a frost tunnel?
Frost tunnels are, broadly, a structure designed to protect plants from frost. There are a few different types of frost tunnels, including high tunnels, low tunnels, and hoop houses. In general, all of these consist of some sort of support structure and cover. The frame usually consists of an arch shaped piece of plastic or metal held in place at the base. The cover can be plastic or cloth depending on how permanent the structure is and what its purpose is. The main difference between these is their size. High tunnels are, well, high. They are generally large enough to bring farm equipment into them. Hoop houses are a bit smaller and easier to set up, but still high enough to for a person to walk inside.
Lastly, low tunnels are the smallest. These usually cover one to a few rows of plants and are low enough that to access the plants, you must remove the cover. These are much more temporary structures and the best solution for a home gardener.
How to protect plants from frost in a raised garden bed
There are a few ways to set up frost tunnels for raised garden beds or in ground beds. Some ways work for either one while others are best for a specific set up. I’ll get into some of the alternative methods at the bottom of the post, but I’ll focus mostly on my method that works best for wooden raised beds, because that’s what I have experience with. I love this method because I swear it is absolutely the easiest way to protect plants from frost in a raised garden and it makes the process to cover everything in the event so easy and fast. As a bonus, you can also use the structure to set up netting if you need to protect your plants from deer or birds, too!
Raised garden bed cover tutorial
Let’s get into it! I’ll start with the simple list of materials you need then get into the quick and easy steps to put it all together. There is only one tool you’ll need for this project, and that is a drill.
Step 1: gather materials
In order to prepare your materials, you’ll first need to do some measuring. Start by measuring the length of your raised bed. Plan on putting one pex pipe support about every 4 ft. To determine the length of each support, you can reach way back in your memory and use the formula for the circumference of a circle… or you can guesstimate. For reference, mine are about 7ft long each each and make for a tunnel about 2 ft tall over my 4 ft wide raised beds. (don’t forget to leave enough room (an extra 3-6 inches) on each end for them to go through the pex clamp.
Lastly, determine how many clamps you’ll need. I suggest using two on each side of each pex pipe for stability, so 4 per pipe section. However, you could really get away with one per side. Having two clamps just help to hold the pipe straight so that it does not lean in or out under the weight of the frost cloth.
Step 2: install clamps
Now that you’ve measured everything out, you should have a pretty good idea of where each pex pipe support should go. Mark these spots, and grab your drill. Installing pex clamps is pretty easy. Simply position them on the inside wall of the raised bed with the hole facing up and down. Then hold the clamp in place and drill a screw into the provided screw hole to fasten it tightly to the raised bed wall. That’s it!
Step 3: Add your pex piping
With all the clamps in place, it’s time to create your tunnel. Simply take on of your pex section at a time and insert each end into the pex clamp. Don’t worry if they feel a bit wobbly. Remember, these are only meant to hold the weight of a light sheet of frost cloth.
Step 4: Cover
All that’s left to do is cover your new tunnel with frost cloth! I use some these little metal clips to hold them to the pex and to the edge of the raised bed. I just ordered them off Amazon hoping they’d work, and the happen to be the perfect size for 1/2” pex piping and for the 1/2” boards that make up the raised bed walls. If your raised beds were made with 3’4” boards, it may be easier to clip the cloth on with a larger size clip.
That’s it! Your raised bed is all set up and ready to protect your plants from frost! But wait, before we move on, I have some other suggestions to get the most out of your new setup.
If you struggle with squirrels digging in your plants, or rabbits using them as a snack, your frost tunnel will serve as protection unit the weather warms. After that, leave your pex supports in place, but replace the frost cloth with bird netting. This way, all the lovely pollinators can still reach your plants, but the squirrels cannot and rabbits.
Your new frost tunnel can protect your plants from more than just frost, too. If you experience a heat wave or have plants that are getting a bit too much sun, swap the frost cloth out for shade cloth, and problem solved!
Other frost protection options for raised beds
If you have metal raised beds, or in-ground flower beds to protect, this post may have been a bit disappointing to you. But don’t worry, I have options for you too! I’ve seen very similar set ups made a few different ways.
For a small lightweight, option, try using flexible poles (these are basically tent poles) inserted directly into the ground. There are lots of kits like this on Amazon. These can protect plants from frost both in raised beds full of cut flowers or out in your landscaping. Just make sure the soil is well compacted or they won’t hold in place. Then you just drape the frost cloth the same way you would in my example above.
PVC piping offers a heavier duty alternative. Check out this tutorial to see how you can set up a frost tunnel using pic pipes and rebar.
And that’s it! I hope you found a helpful solution in here! Protecting plants from frost can be a bit daunting. But it’s such an important part of gardening, especially if you want to get a jump on those spring blooms! If it’s still way too cold outside to be thinking of gardening even with frost protection, here are some other spring garden tasks you can do first before jumping into the rest of your spring garden checklist! And if you want the spring flowers without worry of frost protection, check out our list of early spring flowers and spring blooming trees!