Early Spring: Planting Outdoors

It's spring and if you're anything like me, you started seedlings indoors way too early because you just couldn't help yourself. My mid February planted seedlings are into their third up-potting, some on their fourth and I'm quickly running out of room in my seed starting area. I need to get my cold frames set up and my polytunnels in place pronto!

This will be my first year using a polytunnel so a lot of trial and error is going to take place. This is my first attempt. I used 1/2 inch electrical conduit in 10 foot lengths for the tunnel hoops. The plastic is 6 mil clear plastic that is 10 feet wide. It was left in one of the sheds (now part of the Megashed) by the previous owner. The cinder blocks and bricks were all Craigslist finds. The bricks were about 4 cents a piece and the cinderblocks I picked up for 50 cents each. I love Craigslist.

While this doesn't look too bad, it has major problems.
1. The plastic isn't wide enough. You can see that it barely comes down to where the pipes meet the bed wall.
2. There is no center support connecting all of the semi circular pipes. This makes the structure less stable than I would like.
3. I cut the plastic too short. You need to have several feet overhang on each end if you want to gather it up like a tootsie roll wrapper. Though the better approach IMHO is to install unmoving end pieces cut to fit at each end of the tunnel.
4. The garden bed above is 21 feet long. I used one long piece of plastic. That will be too long to open and close the sides without difficulty.

After doing some more internet research (something I do far too much), I found a picture that I will be attempting to copy.

This is my inspiration and has seemingly solved all of the problems that exist in my trial run. I already have the pipes in place. I used 1/2 inch diameter, 10 foot long electrical conduit. You can use the white plumbing pipe as well though I've read that the grey electrical conduit holds up to UV much longer. It is also cheaper, $1.35 vs  $1.68 at Home Depot.

Now that you can see what I want to do, here's how I'd go about doing it.

INSTALLING THE HOOPS:

- Space hoops 2 - 2 1/2 feet apart.

-If you have raised beds made out of cinderblocks, you can just place the 10 foot long pipes in the open holes opposite one another and then fill with dirt. If you have clay soil, tamping the dirt into the holes will hold them securely enough. If your dirt doesn't compact will, you might consider filling the hole with concrete. If I were to do that, I'd buy a length of 3/4 inch pipe, cut them into shorter lengths equal to the height of the blocks. I would then concrete that length into the hole. This way you could slide the 1/2 inch pipe into the 3/4 inch sections. This just makes the system less permanent if you want to ever dismantle the polytunnel.

-If you have raised beds with wooden, you can secure the hoops a couple of ways. I'll be using the method shown in the above picture. Here's a blown up version of it.

As you can see, the used 3/4 inch sections and screwed them directly to the wooden wall of the raised bed. Then then slid their 1/2 inch sections into them (as describe in the cinderblock/concrete method). Again, this would allow you to remove the hoops if you only wanted your poly tunnel to be a seasonal fixture.

-A second method would be to use 1/2 pipe brackets. Use these to secure your 1/2 diameter hoops directly to the inner or outer wall of your garden bed.

INSTALLING THE CROSS MEMBER:

-The cross member will be unmoving. In the picture above, it is the upper most piece of lumber. Though I have to extrapolate how it's attached, my guess is that it was placed at the apex of the PVC hoops and then screwed in place. Or at least that's how I'm going to do it. I'll use 2x2 redwood balusters that I got for free off Craigslist. I'll pre-drill into the 2x2's and the pipes and then secure them together with 2 inch exterior screws.

INSTALLING THE PLASTIC:

I purchased pipe clamps from the Greenhouse Megastore online. They were only 50 cents each and you will only need 6 per end.

This is how I'll attach my cut-to-fit plastic ends. Please not in the picture of the polytunnel end, they didn't go all the way up. This will allow for ventilation when your sides are down.

To install the plastic sides, purchase plastic that will overlap the sides of your raise bed by at least a foot. In my case, I'll need 12 foot wide stock. I'll lay my plastic over the hoops so that there is an even amount on both sides. I think I'll make my sections 10 feet long making it easier to raise and lower the sides instead of one long piece.

I'll sandwich each end of plastic between 2x2 lumber and furring strips using 1 5/8 inch exterior screws as connectors. Then all I'll have to do is roll the plastic up the sides (like a roller shade), using the 2x2 as the core and then use bungee cords to hold it up as they did in the inspiration polytunnel or use any other clamping method you can think of.

This is today's project for me. I hope this helps anyone else that wants to make one themselves. Just leave a comment in the comment section if I missed anything or if you need clarification on any steps. 

One difference between the inspiration tunnel and my tunnel will be the t-posts they used on the ends. I'm going to skip that step. I'll add them later if I find I need to add more stability to the structure.