At each end we anchored the plastic with 2 40# building blocks. We filled 40 5 or 10 gallon plastic pots with compost to anchor the plastic along the sides. We anchored one end and unrolled the plastic along the windward side. We then worked down the side, one person pulled the plastic over the hoops and the other set the pots on the one foot of plastic along the edge. Then we anchored the other end and then the remaining side.
With a 10 mph wind with 20 mph gusts, total time spent was about 2 hours which included the time spent filling the pots with compost. Filling was pretty fast -- we laid out the pots in a square and dumped about two bucket loads of compost on top and smoothed it by hand to fill the pots. We decided to use compost because we have a lot of it and when it comes time to take down the tunnels, we can just dump the compost in the beds. I believe that one the materials have been laid out, two people can put up a house in about half an hour and take it down in about the same time.
After about a half hour some of the lee side pots tipped over as the plastic billowed out during a gust of wind. We watered the pots to make them heavier, moved them a bit to the center between the hoops and tilted them some toward the tunnel to make them harder to fall over. There were no more problems, even the next day when the wind reached 20 mph. We'll work on some modifications so the tunnel can withstand about 40 mph gusts and a light snow load. We can add heavier side weights, tie the hoops together with a rope purlin and add some tie-down ropes between the hoops. Our steel-hooped houses have been fine with winds of 60 mph.
This first tunnel covered a bed of late snap beans that are about ready to blossom. It's pretty late in the season so we don't know if they will produce anything before we get a hard freeze. We're going to build two more and cover two beds of summer squash that started producing about two weeks ago.
Anyway, we are pretty happy about results so far! Our fall CSA starts in about three weeks so these tunnels will help ensure we have enough produce for our subscribers.
4 comments:
Hi Tim
I was interested to see you use rebar as the support for your hoops. I too have used it but I found that it rusted pretty quickly so I switched to using 8mm (1/3" ?) galavanised rod. The cost here in Oz was about the same and of course it doesn't rust. Had you considered using it?
I know from my web researches that using plastic on hoop houses in the US is pretty much universal. If you look at my website you will see that we use a different material. I assume that you use plastic sheeting purely to raise the temperature and wonder if you have any data on how much?
Best of luck with your beans!
Cheers
John
http://www.veggiepatch.com.au
John, Thanks for your comments. Sorry for the long delay but I'm new at the blogging game. I've not seen the galvanized rods anywhere. What are they used for and where might you find them?
Regarding the plastic, it's really to protect the whole growing environment and heat is part of it. Also pests, weeds, etc. are important.
The 6mil plastic we use, when stretched tight, will carry a pretty good snow load. I've now built 5 of what I'm calling "caterpillar tents" with 3mil non-UV treated plastic and the latest design recently withstood a 45 mph wind -- the others blew apart.
Tim, I'm a little confused because in your 7 Oct post you wrote that you use 6mil but then also mentioned using 3mil at the end of the same paragraph. Do you use both? Have you found that the 3mil was not durable enough?
I'd been planning on using 8ft lengths of piping for the hoops but started wondering if that would be too short. Then I read your Nov 21blog that said you were trying different lengths. I'd expect a lot of trouble with too wide a hoop due to rain or snow accumulation, any lessons learned from your experiments? I have 4ft wide beds as well.
You mentioned 20 10ft sections of "brown" piping. I'm familiar with white (rigid) and black (that comes in big rolls) but not really with brown. I'm also curious about the type of store of store did you go to for re you went to for your parts because the black piping I found at Home Depot was around $22 for a 100ft roll but it looks like you got your piping for a lot better price (the equivalent of $12.50 per 100ft).
Thanks,
Dave
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