Protective Dome Support

I have a question about the PDS as illustrated in the new SFG book on pages 72 and 73. It shows 2 ten foot PVC pipes, 1/2 inch in diameter, stretched from corner to corner, and connected with a plastic tie. A shade net or other screen can be laid on top of the PDS to protect the plants from too much sun, cold, or wind.

Has anyone had experience with this? Is it strong enough to withstand heavy rain or wind without toppling over or being blown down?

I can get some pretty heavy winds in my SFG due to it being up a hill on the SW side of a lake. I recently built this dome using hula hoops, painters plastic and clothes pins:

I originally tried clothes-pinning the plastic to the hoops but the cold would have blown under the plastic due to the excess plastic that I'm unwilling to cut hanging over, so now I have the plastic clothes-pinned to the rebar, which I'll use later for my trellis, on one side and a board on top of the excess plastic on the other.

It's only been 5 days, one nite of snow flurries, 2 of rain. All was well thru that and we're expecting heavy winds for the next few days starting today. If it stays on over the next few days I'll make more for my other boxes.

CC

I put up the hoop house illustrated in the book late last summer, the afternoon immediately preceding our first killing frost.

It held up well. That is, until the first windstorm. In this vicinity, winds frequently get to 40 mph and can reach 80 mph on rare occasions.

Anyway, the structure NEARLY blew over. Then, I suddenly remembered I'd purchased some clips from a nursery last summer, not really knowing what their purpose was. An "aha" moment convinced me to use them to attach the plastic to the PVC.

In addition, of course, I used 2x4s, large rocks, and bricks to secure the overhanging plastic. Now that I know what works, I can assure you that with these enhancements, the structure is actually quite stable. It also held several inches of snow.

erbarnett wrote:I have a question about the PDS as illustrated in the new SFG book on pages 72 and 73. It shows 2 ten foot PVC pipes, 1/2 inch in diameter, stretched from corner to corner, and connected with a plastic tie. A shade net or other screen can be laid on top of the PDS to protect the plants from too much sun, cold, or wind.

Has anyone had experience with this? Is it strong enough to withstand heavy rain or wind without toppling over or being blown down?

I constructed 2 of these on my 3.5' x 3.5' beds earlier this spring. I used 1/2" pvc and 3.5 mil plastic. I cut the pvc down 20" because my beds are a little smaller than 4' beds. I attached the plastic to the pvc using clips from the office supply store (the biggest ones they had)2 on each "leg". I also put the pvc on the inside of the bed, and the plastic is longer on the outside and weighted down with some bricks. So far it has withstood 50 mph gusts, snow (dry snow, not the wet, heavy kind) and very strong sun.

I dont think the plastic is going to last. But for right now it has served its purpose, which was to get the bed warmed up and a place to put my flats of plants. I might go back to the big box store and get some clamps and attach the pvc to the outside...and I will probably go to a fabric store and buy some tulle.

That was how I intended for mine to be but my husband decided to secure the pvc to the outside of the boxes instead. I don't put clamps on my frost blankets when I need them though, I just secure the blankets on the ground with bricks (I have quite a bit of overhang)...this has worked fine for me.

Capecoddess and others,

I want to make a structure like the one you showed with diagonal arcs, but thought there would be lots of excess plastic covering the dome which would be a waste and clumsy to deal with. Your covering seems to fit neatly. Is it because it is not a very tall ( more flat) dome? Or, did you trim or fold the excess out of the way somehow? I was thinking of making a dome-shaped vinyl cap to fit over the arcs. I thought the most tailored fit could be made by making a "Beenie"-type hat that would require sewing panels between each arc like an umbrella is made. It would be like a rainfly for a domed camping tent. With only two arcs like yours it would require four panels. With this construction I thought I could just pop the cover off and on quickly as I needed access to the plants. It would also be easy to store the hats compactly by folding them up. It is apparently possible to sew vinyl but not easy. I found "batten tape" in a gardening catalog designed  for stapling the plastic sheet to a wood support. Apply the tape to the plastic sheet and staple through it into the wood. Perhaps I could sew two pieces of plastic sheet together through tape so the seam would be less likely to tear out. Has  anybody tried this? Am I making it all too complicated to be worth the trouble?
I have seen supports using PVC but I found that grey plastic electrical conduit is less expensive,more flexible and possibly less brittle in the cold. My brother told me his PVC broke after a while. It is especially handy because each 10 foot length is flared on one end to allow  another ten foot length to slide into it thus extending it. This allows one to make any length with no waste. I fashioned one in this way about thirty feet long to arc over my entire garden but did not end up using it.
I will be grateful for any suggestions or comments. Thanks, Ken

Hi Ken, welcome to the forum! 

Your dome design with the panels sounds really neat!  if you make it please post photos!
I'm just a simple girl and everything needs to be easy or I won't do it. My sewing machine hasn't seen the light of day for over three decades.  In the photo above the excess plastic is twisted on one side to pull it tight on the other sides.  Then I think I placed a brick or some wood on the twisted excess. 

Instructions for this dome are in the All New Square Foot Gardening book. Have you read it?  You can make it as intricate or as simple as you like, whatever works for you and pleases you.  

Do you have any photos of what you've got going on now? Would love to see them.

CC

CapeCoddess,
Thanks for your reply. I do have the book and began square foot gardening last year. I have not yet tried to make the dome. I think I will buy the tape and try it. I will update you about it. Ken

Ordered the tape. Backordered. Hopefully will ship by 4/14