Keeping Dry: Securing Tunnel Cloches

The past few days in the Seattle area have been so lovely, I think the weather Gods are apologizing for the veritable monsoon of rain that dumped on us two weeks ago. 
If you are not in the Maritime Northwest, you might be shaking your head right now, saying: “Seattle is called Rain City for a reason. Suck it up.” And it’s true: it rains a lot here, in terms of number of days per year that precipitation falls. But the total volume of water that falls to earth in our bioregion isn’t any more than Chicago and is quite a bit less than New York. See, we excel in drizzle. Many, many, many days of drizzle.
So the sky-opens-and-water-is dumped-down-by-the-bucketful rain from two weeks ago was quite atypical. It ravaged a flat of seedlings I had set out to harden off; just full-on shredded the tender leaves. It left puddles of standing water in my loose-soiled raised beds. It washed fertile mulch off garden beds and into paths in rivulets. It fully saturated the soil, which was none too dry before.
After the monsoon I knew I had to cover my beds to allow them to start to dry out for planting. This time I wasn’t trying to create a better microclimate for seed sowing or transplants, I was just trying to keep any additional rain off.
We have PVC Framed Hoops much like these installed on most of our beds. So constructing a plastic tunnel cloche was just a question of throwing some 4 mil plastic over the top and securing. I know a lot of people advocate securing plastic or row cover to PVC hoops with clips but I’ve found that in a good wind the clips tend to just pop off and the cover will come loose.
Instead, we use a good length of cheap robe and a bungee cord to secure the plastic all around the wooden outside frame of our raised beds. Here’s how we do it.
Get some rope and a bungee cord. A “stiffer” bungee and a rope without too much stretch works best. Figure out how long your rope will need to be to wrap the perimeter of your bed and be held taught by the bungee. The first time you do this, it’s a good idea to measure “in the field” so you can see how stretchy your rope and bungee are when pulled tight. Cut the rope to the appropriate length. I cut my rope 25 feet long to wrap a 4’x8′ bed. This gives me plenty of room to tie knots at the end.

Tie a sturdy slip knot in both ends of the rope.

Hook the bungee into the loop of one of the knots.

One 10’x24′ foot roll of 4 mil poly cut in half to make two 10’x12′ pieces is just the right size to cover two of our 4’x8′ beds fitted with low PVC hoops. It’s easiest to measure and cut the poly inside or in a non-windy, level spot.

Cover the PVC hoops with the plastic, making the whole thing even all around.

Pull the excess plastic to the short ends of the bed, making the long ends as smooth and flush to the bed as possible.  Pull the rope around the bed and secure with the bungee. It is important that the rope be pulled tight so that it will hold the sides of the cloche down against any spring winds.

The finished product. All our little beds, cloched up and ready to laugh off the rains.

It’s a good thing we got these done when we did; five minutes after completion of this project a hail storm started, followed by yet more buckets of water.

Now that we are having some clear and sunny days the cloches are actually starting to get a little heat built up. I have the ends of each of them vented a bit for airflow and to prevent overheating.

How do you use low tunnels, cold frames or cloches?


  1. says

    got my 1 tunnel done, more to go… a bit still to cold here as i'm higher in elevation than you and our season is that much shorter… the weather is such a tease… going to be awesome here today too :D
    i have a 'house' as well which i cover with reemay and keep my tomatoes in.. it's high enough to go through the entire season and extends my growing period at least a month..and some years i can overwinter quite a few different cold season crops..

  2. says

    I've been hearing a lot about it being a la nina year, and that therefore the season is starting late and ending early. I am starting some of my seeds late (just sprouted a bunch), but seedingout some every weekend. I won't be hardening anything off until about 10 days from now, because it's been to crazy rainy and cold here (Vancouver).

    Because of the late start and the probable early ending I'm building a large 7' walk in polytunnel, 10' by 15'. It will need good ventilation (as I'm sure you know, humidity around here is the major problem), but I think it will help extend the season and also bring the heat up a bit for those plants first coming out.

    That's my newbie thought at least, I haven't built polytunnels before!

  3. says

    Love mine, though only once have the clips poped off. Not bad in three years.

    As for your luck. the first time I installed mine we got 4 inches of snow in April that night. Held like a charm!

  4. John says

    Thanks for posting this. I just lost my plastic cover on my low tunnels do to sustained 40-50 mph winds out in Chicagoland. I combined your bungee rope with an additional tie down idea inspired from here:
    I have 4′ by 11′ raised beds and we just put screw eyes near the ground on the outside of the bed at each hoop. Then we just added extra line and the whole thing is stable now even with good gusts. Let me know if you would like me to send you a pic.

  5. Tiff says

    Hi, there. I have begun to call your site a “time suck” oh how I could live my life like this! Since that isn’t possible because there is so much living to do, I have a question. I loved your ‘How too’ on this post,but it left me still a little stumped. I’m going to try a hoop house over the new bed I built the year. It’s 4×20 and the wood sides are 12″ high. I rent so everything has to be removable,so rebar and wooden stakes hold up all of my raised beds. How can I affix a hoop house onto this bed,knowing with too much tension on the boards them selves? Also I want to tell you that your blog and the info you share is amazing! Thanks, tiff

    • says

      Hi Tiff, glad to be your time suck of choice. ;) Here’s what I would do: build a pvc frame low tunnel and measure it so the posts line up with the rebar supports you already have. Slip the pvc posts over the rebar that is already holding up the bed. You can get the narrow pvc to bend over a 4′ high bed, which is how we did it, but my neighbor built their pvc low tunnel frames with straight sides and 60-degree angle connectors corners. Instead of being a hoop, the top of their frames look like half a hexagon. If we were going to make more hoops, I would do it the way my neighbor did it because it takes the tension out of the pvc. Make sure you put in a top bar running lengthwise to hold everything together and so the plastic doesn’t slump between pvc sections.

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