My PVC Hoophouse page is by far the most popular page on this site. Since many people are using the PVC hoophouse, it's not surprising that I get a lot of questions about it. The vast majority of times the questions fall under the topics I've listed on this page. If your question isn't listed here, please feel free to write me.
Why 'Visqueen' plastic instead of greenhouse plastic?
There are several reasons for picking Visqueen-type plastic (note that while 'Visqueen' is a brand-name, I'm really just referring to any clear plastic sheeting available at a hardware or paint store). First, we're talking about a temporary structure that is designed to be moved around in the garden from season to season. The sheeting gets a fair bit of wear and tear from this. Not only is dragging the plastic around the garden likely to cause occasional tears; but the use of clips, clamps, and other fasteners that get attached and removed repeatedly eventually damages the sheeting.
Also, PVC pipe will, over a long period of time, interact with plastic sheeting. This means if you use greenhouse plastic it's probably not going to last nearly as long as you'd like. You can probably get around this by keeping the PVC pipe painted. Another way to avoid this problem is to use alternate materials like metal pipe, wood lath, concrete reinforcing screen, etc. If you attempt this, though, you're on your own - I have never tried it.
Another reason is cost - greenhouse plastic costs many times as much as Visqueen. Given the rough treatment the plastic can get in the garden, and the likely chemical interaction with PVC pipe, I can't really justify the expense.
Of course for a more permanent structure greenhouse plastic would be the right choice. You wouldn't want to use PVC to build that permanent structure though, because of the chemical interaction issue.
Which way should it be oriented with respect to wind?
The PVC hoophouse will work best if it is placed sideways into the wind, as long as the plastic sheeting is well anchored. This can be accomplished by sandwiching the ends of the plastic between length of 2x4 lumber, or by burying the ends of the plastic in the ground.
Can I make it bigger?
You can extend the length as far as you want - just add more ribs and a longer piece of plastic sheet.
If you want to make the PVC hoophouse taller and/or wider, you'll need to modify the basic design. The structure will need more cross-bracing than the single ridgeline found in my design. It's also likely that some sort of internal bracing will be needed.
What's the best way to heat it?
The PVC hoophouse isn't very airtight, so heating it would be terribly inefficient. It's not really designed for that purpose. If you want a heated space I would suggest you look at real honest-to-goodness greenhouses or similar structures.
Even without supplemental heat, though, the PVC hoophouse protects plants from temperature extremes. It is a great tool for overwintering plants that can handle cold, but are usually done in by one of our infrequent cold snaps. It's also great at overwintering otherwise hardy plants that cannot handle the constant winter rain our climate features.
All contents © Travis Saling
This page was last updated July 9, 2011