For less than £25, you can make your own DIY raised bed polytunnel. Perfect for urban growers with backyards or small patios.
If you want to grow juicy fruit and veg that are normally a bit shy in our climate, you’re going to need a greenhouse. The trouble is, you might not have space for a full-on greenhouse. But there may be a solution.
This will work even if you have a concrete backyard or a small front patio. In fact, it’ll work anywhere you can create a raised bed, even if it’s only a small one.
With a few bamboo sticks, some plastic piping, a painter’s dust sheet and some string, you can create your own raised bed polytunnel that will help you grow your own juicy fruit and veg and extend your growing season for less than £25.
Whatever you have or decide to make, with just a few simple items, you can create an up and over polytunnel that will keep the rain off your plants whilst protecting them from sudden drops in temperature and ultimately extending your season.
In my case, I’m using this polytunnel bed for my tomatoes, peppers, melons and cucumbers.
What You’ll Need to Create Your Own DIY Raised Bed Polytunnel:
- MDPE Plumbing Pipe (20mm x 20m): £14.00
- MDPE Pipe Clips 25mm: £3.50
- Heavy Duty Polythene Dust Sheet: £6.99
- Two lengths of wood the same length as your beds (20mm x 45mm x your length)
- 6 bamboo sticks : £1.99 (for 20 bamboo sticks)
- Staple Gun
The Benefits of an Up-and-Over Polytunnel
Plants like sun. Real sun and fresh air. The polytunnel is a fantastic aid, but nothing beats being out in the open. Being out in the open encourages pollinators like bees and other insects and contributes to the overall natural ecosystem within your backyard.
If your plants were locked in a greenhouse forever, the chances of attracting pests that deterrents or predators can’t get to are increased. With this closed system, you’d have to think of ways to ‘introduce’ deterrents or predators (or worse, pesticides) into the greenhouse yourself. You might have no problem doing this, but I’d rather let nature take it’s course given the choice.
The most effective way to create an up and over is to build a simple slide mechanism that allows the polytunnel canopy to be slid over the top and out of the way.
Here’s how you can do it.
Step One: Bamboo Structure
Push your bamboo sticks into your bed. Usually, in urban environments, there’ll be a fixed depth for your particular bed, either because your garden was built on top of the hardcore the builders left behind or because your bed is built up off your concrete yard floor. This means when you push the bamboo in, they’ll usually settle at a constant depth.
If they don’t, push the bamboo sticks into an appropriate depth, take a measurement and repeat for the other stakes.
I used 6 sticks for my structural support, because that seemed best for my length of bed. If you have a shorter bed, you may only need 4 or, if you have a longer bed, you may need 8.
Step Two: Create the Hoops
Once your sticks are in place, place an open end of the MDPE pipe over one of the corners. Push down firmly until the pipe feels relatively solid. “Hoop” it over to the opposite bamboo stick and take a measurement of where you want to cut off. Cut off the pipe at the appropriate length then slide this end over the stick.
You will have created your first “hoop”.
Repeat the process for the remaining hoops.
Step Three: Attach Wood to Polythene Canopy
Lay out the canopy in an open space. You don’t need to trim down the sheet. We can overcome the problem of size by ‘rolling up’ the sides once the wood baton is attached to find the appropriate length.
Once the sheet is laid flat, take your first length of wood and place it on the edge of the sheet in the centre. Fold the edge of the sheet up and around the wood and then proceed to staple the sheet down to the wood. Go along the full length, putting a staple in every 3/4 inches.
Once you’ve done your first ‘layer’, roll the wood up into the sheet again, making sure to keep the sheet taught against the wood the entire time. Once you’ve turned the wood into the sheet a couple of turns, staple it down again, then do one final roll of a few turns and staple again so that the sheet has a really good hold on the baton.
Do the same for the opposite side of the sheet, taking special care to not roll up too short so that it won’t cover your bed over the hoops.
Step Four: Screw Pipe Clips to Wood
Once both sides of the sheet are securely fastened to the wooden batons, you need to screw 3 pipe clips to one side. Also, you only screw as many pipe clips here as you have hoops on that side. So, if you used 6 bamboo sticks, you’ll have 3 hoops and therefore need 3 pipe clips on each wooden baton. If you only used 4 bamboo sticks, you’ll need two etc.
We only screw to one side for the moment because we fasten one side to the hoops before we turn up the other side to the perfect length over the hoops.
Measure the distance of the hoops on your raised bed. Make corresponding marks at the same measurements on your wooden baton. When you do this, make sure you mark the side of the baton that will be on the inside of the polytunnel.
Once the measurements on your wood match up with the measurements of your hoops on the raised bed, you can drill small holes into the wood with your drill. You need to drill these guide holes into the wood to prevent the wood from splitting when you screw in the clips.
Once the guide holes are done, you can proceed to screwing in the pipe clips (remember, it’s one side only for now).
Step Five: Fit Canopy to the Hoops
After the pipe clips are fastened securely, you can bunch up the canopy and carry it over to your raised bed.
Clip the pipe clips to the corresponding hoops on one side of your bed.
Now lift the remainder of the canopy up and over the hoops to the other side. Pull the canopy taught. You’ll be able to see now how much play you have left in the length of the canopy.
Turn up the wooden baton by ‘rolling’ it up and pulling the canopy tight. Repeat these turns until your canopy is taught across the top and is hanging perfectly at the base of the bed. Make sure the side that is clipped in is resting flush against the base.
Once the length is perfect on the unfastened side, use your staple gun to pin the final position of the sheet to the wood. Now lift the wood and turn it back one turn so that you can screw the pipe clips onto the wood at the appropriate position.
Make marks at the appropriate place in the wood that correspond to the hoops where the final 3 clips need to be screwed. Remember to use your drill to drill a guide hole before trying to screw the clips into the wood
Once all clips are in, clip the sheet to the hoops.
Step Six: Tie Down the Sides
Once both long sides are fastened into place by their clips, the ends will need to be pulled taught and tied down. To do this, grab any excess sheet and pull it away from the polytunnel. Bunch it all up together and twist it into a tight bunch.
Take your string and tie in the bunch.
Do the same at both ends.
Afterwards screw a screw into each end of your bed and leave enough of the screw head out that you can tie the ends of the polytunnel to the screw via the string at the bunches. When you tie the ends down to the screw, make sure they are pulled taught because this will give your polytunnel it’s final structural shape and help rain run off efficiently.
Congratulations, You’ve Now Got a New Raised Bed Polytunnel!
Now you have your very own sheltered space for your plants, make sure you use it correctly.
Don’t waste the shelter by planting crops in here that would do just as well outside. Use this bed for the extra things you wouldn’t normally be able to grow – like tomatoes, peppers, melons or cucumber.
On hot days, make sure you open it up to give the plants some fresh air and let in those beneficial insects that will keep your backyard ecosystem in check.
If you have any ideas on how this simple design could be improved, please feel free to share them below. If you’ve tried it and want to let everyone else know how it did for you that would be really cool to hear too.
Remember, this is just a tiny snapshot of the small-space solutions and resilient ideas I’m testing out. If you sign up to my email list, I’ll send you everything I have in one handy, accessible completely free Urban Grower’s Handbook (pdf format).
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