Sunday, March 29, 2015

Bulding things - hoophouse

I spent the day today putting up a small hoophouse.  It's where I'll start my vegetables, and later in the season I'll probably put hot-weather crops into it.  Tomatoes grow pretty well, but we don't seem to get enough heat to make them red and lucious, so along with the peppers and the watermelon they'll be here.

The basic structure is pretty simple; it's galvanized pipe (the top rail from chain link fences) bent into a hoop, and fitted together using the swage that comes already formed on the pipe.  Each half-circle is inserted into
a heavier-duty pipe, about 4' long, that's driven into the ground with a fence post pounder.

I do this because I want the greenhouse to be tall enough that I can drive a tractor in or through it, to make dirt delivery and removal easier, and just in case... well, i'm not sure why, but I've learned that if I don't make things big enough to drive a tractor into them that suddenly I have an urgent need to do so, usually involving saving time or work, and so now when I'm doing things I automatically add a little height or width or both.

Once the hoops are up, I put a double-row of wood along the bottom and at the base of the bent part of the hoops.  I do this because sometimes it's handy to be able to house animals in this, and if I provide that railing, I can just attach some 36" fencing and prevent the animals from damaging the plastic, or escaping.  These hoop houses make pretty good chicken or turkey coops, or a place to stash a sick piglet or two, or a dog house, in a pinch.
I'm using recycled lumber for this purpose; I try to keep and re-use any lumber that comes from projects or teardowns, and I spend a little bit of time removing the nails.
I wonder why people use galvanized nails, honestly.  For this project I'd expect the plastic to last 4 years before it needs a new covering, and the wood will probably last 10 years (it'll be warm and humid, but douglas fir, which is what these boards are, is pretty resistant to it as long as it's not touching dirt, and these nails will probably outlive me.  Plain old iron nails are used to join the boards.
at the top of each hoop is the swage that connects the two pipes.  I've found that the lip on the pipe will eventually wear through the plastic cover, so I take a ladder and a couple of minutes and cover each of the 7 joints.
With the double rail in (you can see top and bottom rails in the pictures above) and the joints taped, I'm ready to pull the plastic over the whole thing.

This particular hoophouse is 15' x 28', with 7 hoops spaced 4' apart.  It's a good size for a hot-climate kitchen garden.  Cilantro, peppers, heat loving stuff that just needs a little boost above average to be sooo much better.

Here's a link to a site that sells a pipe bending tool for $60.  You an do the same sort of thing with wood blocks screwed to a piece of plywood in the arc you want to bend.

Happy greenhousing!


sailj32 said...

Seems like "7 hoops spaced 4' apart" would be 24' long. Nice ideas here. How do you make the large smooth bends?

I've been using 1/2" PVC pipe slipped over rebar posts to make a 4' x 17' hoop house, also for tomatos and peppers. It's walk-in height but built over large raised planting beds so no way to get a tractor in anyway.


Mountain Walker said...

I am so jealous! I would LOVE a couple of hoop houses for tomatoes and peppers. We live in a bit of a low area and the nights are chilly even in the summer. A hoop house would give us the night protection to finally offer us a red tomato. But we also get high winds and I'm afraid the plastic would be reduced to tatters before the summer's end. :(

Bruce King said...

Sail: to make the bends in the conduits you can either use a conduit bending tool (i'll put a pic of one at the bottom of the post) or you can lay out the curve you want on a sheet of plywood with blocks - or both. Use the conduit bender to bend the pipe and then use your layed-out curve to see how much more you have to bend. For this size hoophouse each conduit is bent 90 degrees over about 6' -- so there's a 2' straight section on each end of the pipe. One of the straight ends goes into the anchoring pipe, the other goes into the opposite pipe. so there's a little flat area at the top of the greenhouse, which is OK in my area - we don't get much snow load, but you might want to angle it a little more than I do if you get lots of snow in the winter.

Bruce King said...

Elizbeth -- I've made my hoophouse taller than it needs to be, and it's pretty well anchored with the pipes driven into the ground. Each anchor pipe has a bolt through it to hold
the wood side braces , which also holds the hoop down. The 4 year plastic for these greenhouses is pretty tough stuff. unless you're talking a lot of 40mph winds, I think you'd be fine.

Or you can remove the plastic during the stormy season and store it. takes about 20 minutes to put it back up.

Mountain Walker said...

I didn't think about taking it down and putting it back up. 20 mins? Hummm, interesting....

Bruce King said...

if you're going to want to take the cover off, buy the channel iron and wiggle wire. You'll find it in greenhouse supply centers. It's a C shaped channel and a piece of stiff wire bent into a zig-zag. you lay the plastic over the channel and insert the wiggle wire into it; the wiggle wire holds the plastic. to remove the plastic you just pull the wiggle wire out.

If you can't find what i'm talking about drop me a note and I'll find a supplier. but I think it's pretty common stuff.