We’ve been using unheated hoop houses and cold frames for years
to extend our growing season here in zone 5.
With just a single layer of 4 mil greenhouse plastic, we grow many cold hardy crops through the fall,
and some, like kale, spinach, mache, and claytonia, through the winter.
Now, with our first frost approaching,
I’d show you how we go about adding a hoop house to one of our 4 x 8 raised beds.
We use ½” PVC pipe for both the hoops and ridge beams of our raised bed hoop houses.
The ridge pipe ties the hoops together, stabilizes the structure, and prevents the plastic from collapsing under a heavy snow.
For a 4 x 8 bed, we typically use 3 hoops,
but if you live in an area that gets even more snow than here in Chicago,
you could always add a fourth.
The hoops can be anchored on the outside of the bed or the inside.
In this case, I chose to anchor them on the inside.
To get the length of the ridge beam,
I marked a 10 foot pvc pipe at about 1 inch past the inner length of the bed,
and cut it to length with a hacksaw.
I’ll need that extra inch to secure the ridge pipe to the hoops, which I’ll show in a minute.
I like the hoops to be a little bigger than half circles.
So, to determine the length of the hoops for a 4 foot wide bed,
I first calculated the circumference of a circle with a 4 foot diameter.
The formula circumference = pi * diameter,
gave me a circumference of 12.56 feet.
So, a perfect half circle would be 6.28 feet.
But since I like the hoops to be a little bigger than a half-circle,
I rounded up to 7 feet and cut the 3 hoop pipes to that length.
To anchor the hoops to the bed,
I drove 20” pieces of rebar into the soil in the four corners
and at the midpoint on each side.
I left about 6” of rebar above the soil
and then simply placed the pipes over the rebar.
Before attaching the ridge pipe,
I capped each end in order to prevent the pipe from tearing the 4 mil plastic covering.
I then secured the pipe to the underside of the hoops
using 3 1 3/8” x 2 1/2” U bolts as shown here.
I tightened the bolts by hand until they were just snug.
It’s not cold enough yet for the plastic covering,
but I went ahead and put it on just for the sake of demonstration.
Soon we’ll finish planting the bed with cold hardy crops
which won’t need to covered until temps are frequently below freezing
or we have a snowfall.
I draped the plastic over the frame,
making sure to leave a roughly equal amount of excess plastic on each side.
I then secured the plastic to the frame using soft rubber tubing and clamps.
The rubber tubing was cut into 3” pieces and slit down one side.
I placed the tubing on first to protect the plastic covering
and then fastened a clamp to the tubing.
You can buy plastic clamps designed for this purpose from greenhouse supply stores,
but I’ve found that this approach does a better job of preventing the plastic
from being blown away by the wind.
Finally, to further secure the plastic and make the hoop house more air tight,
I placed weights on the excess plastic around the outside of the bed.
Eventually, the snow will cover the excess plastic and form a nice seal around the hoop house.
When this happens, we’ll only open the bed on one side
and leave he snow to cover and insulate the rest of the perimeter.
With this new hoop house,
we now have 3 hoop houses and 2 cold frames
and hope to have even more fresh veggies to eat this fall and winter.
For a list of what we’re growing under cover,
please see the description below.
Well, that's all for now.
Thank you very much for watching,
and until next time remember
you can change the world one yard at a time.