FLORENCE, S.C. -- In a Morning News column on January 2017, I described how to build a small greenhouse from a simple kit, which I purchased at a local “cheap tool store.”
It has held up remarkably well, and I have no complaints. Well, no major complaints. It cost me more than $1,000 for the total project, which included the kit, a concrete base and installing an electric line and a water supply.
A much cheaper alternative to a greenhouse is a cattle panel “hoop house.” A hoop house consists of plastic film stretched over arced cattle panels.
Cattle panels, or feedlot panels, are made of welded, galvanized 4-gauge steel. They are 16 feet long and a little more than 4 feet high. You can buy one for less than $25 at your local agricultural supply store. These panels are extremely sturdy but flexible enough to bend into an arc.
To make the frame for a simple hoop house, you bend a cattle panel so that the ends are touching the ground. Then you anchor it to the ground using rebar, or by arcing it inside a raised bed made of wood. Using strong wire or cable ties, you can connect multiple panels to each other. Three cattle panels next to each other will make a hoop house slightly longer than 12-feet.
How high the hoop house is depends on how much of a bend you put in the panels. For example, if the hoop house is 8 feet wide, the peak height will be around 6 feet high. That’s high enough for most people to stand up and walk around inside, but you have to crouch along the sides.
Once you establish the framework, you then secure clear or translucent, heavy-duty plastic film on the outside of the panels. The film I used is 4-mil plastic sheeting used for dropcloths and construction projects.
The easiest way to attach the plastic is to wrap it over the cattle panel and then lay bricks or concrete blocks on the plastic where it touches the ground. You could also lay a pipe or a piece of lumber on the plastic, but those will need to be anchored into the ground.
On each end, drape the plastic to the ground and then cut a vertical slit for access and ventilation. When you want it closed, you can use tarp clips. You can even attach ropes or bungee cords to the clips for more anchoring.
The main disadvantage with that simple type of hoop house is the relatively small size and the fact that you need to monitor the temperature inside frequently. Opening and closing the ends of the hoop house will help cool it on sunny, warm days. And you can run a small heater inside when it’s really cold outside. But it’s a semi-permanent structure, at best. The plastic sheeting will break down over time and need replacement, and the wood will eventually rot.
If you want the hoop house higher or sturdier, you can build one like the one I recently made, as shown in the accompanying photo. You will need to make a base out of wood, blocks or other materials. Then the arc of the panel can be more shallow, and the span inside will be wider, because of less arc.
For example, I bent the cattle panels so that they span 10 feet. My base is 2 feet high, so the peak height is more than 7 feet.
In this more permanent design, I first set these treated 4-by-4 posts 2 feet deep in the ground with concrete. Then I screwed in deck boards, on their side, to the tops of those posts. I left about 3 inches of the deck board exposed above the top of the posts.
Next, I bent the cattle panels, and they fit into a ledge that was created. I then used heavy-duty fence staples to secure the panels to the deck boards and posts.
I connected the panels to each other with plastic zip ties and wire. I then attached corrugated clear plastic panels along the bottom. This allows light in but keeps out rabbits and other animals.
The ends of the hoop house are framed in with lumber. I set upright 4-by-4s in the ground with concrete, then attached them to the side walls with 2-by-4 lumber. For air flow, I made four hinged, window-type vents, two on each end. I attached sturdy hardware cloth around the vents to keep critters out when the vents are open.
I also made a door on one end and stapled clear plastic film to it. For even more ventilation on sunny days, I made a large, hinged window on the rear end of the hoop house. Again, I stapled the plastic to the lumber frame of the window.
Finally, I pulled the plastic up and over the cattle panels, then used a staple gun to attach the plastic film to the wooden framework. Wherever there is a seam between two edges of plastic film, I used clear housewrap tape meant for exterior use.
All said and done, this hoop house cost less than $500. It’s much cheaper than a greenhouse!
Once you have built the hoop house, you can either plant directly in the ground or in containers, or make shelving for growing seedlings for transplants. Essentially, this acts like a large cold frame in which you can get a head start on the growing season.
If nothing else, you can retreat to the warmth of this structure in the middle of winter and have a Hawaiian luau; then it would be a hula hoop house!
Greg Pryor can be reached at firstname.lastname@example.org.