Over the past few weeks a lot of progress has been made on the redhouse. First, the name of the project changed. As we got the frame built, my son who is 8 started calling it the “redhouse” instead of greenhouse because of the red burgundy paint we used. I liked the name.
After painting we built the arches that will act as the equivalent to a Mittleider t-frame. The reason there is no “t” in the frame is because we are maximizing wood usage. The outer bed will also act as the support wall for the greenhouse film. The benefit is, I can fit two beds in the redhouse. The drawback is, the plants will be very close to the wall. After building each arch, we put the arches in the ground from 12-15″. The ground we are working with has a slope. To make the arch level, one side is more shallow in the ground than the other.
Oregon is rainy, so instead of using dirt or worse: cement to secure the posts, we used 1/4″ and 3/4″ crushed rock to allow for more drainage.
Once both arches were up, we painted and laid the 2×10 boards that will become the garden bed.
We also painted and installed some 2×4″ boards at the top to support the pvc hoops.
Once that was done, I created a base for the inner-bed tubing. I used a 36″ x 2.5″ 12 guage aluminum sheet as the base and used zip ties to secure the tubing to the base. Over the tubes in strategic location I put thin sheets of aluminum that are typically used with pex for radiant heating applications.
Under the aluminum and tubes I put a sheet of reflective insulation. I probably could have gone thicker, but this is okay for now.
I put two holes in the board and attached braided tube for the inlet and outlet. PEX tubing is not UV protected. So I don’t want it exposed to the sun. It’s also not very flexible. So the braided tubing is great for in between the pex, the pump and the earth.
Now that the inner tubes are installed and in place, time for the soil. Following the Mittleider pattern, I’m using bark dust. Normally the Mittleider system calls for traditional sawdust. This fine dark hemlock dust, however, looks great and looks could help with heat absorption because of the dark color. I mixed with about 30% sand and dumped it in the bed.
For this 12 ft x 18″ bed, I used 400lbs of dust and close to half a cubic yard of hemlock dust.
Irrigation plumbing time. Nearly following the Mittleider system by the book, I got thin wall 3/4″ pvc and drilled tiny boles in it for water to come out. I also installed some ball valves so I can adjust the pressure and also close off the second bed if needed. A bit about the second bed. I’m assuming for the moment that I will not be able to heat/cool the second bed. I’m being conservative. If the first bed’s temperature is easy to maintain, I will add the second bed to the system next season.
The redhouse.is coming together nicely. Once I test the irrigation system and install the controller, I’ll transplant some bathroom tomatoes that are getting too big for the bathtub. The only thing left after that is to attach the greenhouse film.