Raised bed in greenhouse

I built a new greenhouse last season and this will be the first season to see if my raised bed trial has any merit. I used hay bales as a base inside a three foot box. This is on the north side of the green house so I am hoping for some insulative value. I used plastic to protect the wood from rot. Mylar on the outside wall only, to reflect any heat from the greenhouse back. Corrugated drain pipe across the tops of the bales attached to a 12volt bilge vent fan. The fan sucks heated air from the greenhouse peak and blows it under the bed. All materials were repurposed from construction cast offs other than the bilge fan. Solar panels from a yard sale power the fan, hay bales were moldy and free. So there is a little over 12 inches of good compost and soil on top of the tubes now and planted. The white green house wall that is visible is row cover behind that on the exterior wall the greenhouse film can be rolled up on hot days to allow additional venting. I do plan on trying black shade cloth at some point on that wall to see if it warms the greenhouse significantly but would still vent. Just to the right of the down tube of the vent you can see a temperature monitor that records humidity and temps and plugs into a USB port for data collection for my trial. I've used the same monitoring device in a similar position without the raised bed previously.
My chicken coop and yard are what you see through the windows on the far end.

wow, should work. I have the pex from my wood furnace buried under my greenhouse (it goes from there to my son's house and ours)..but this year we lost our furnace on Feb 29, so obviously it didn't do us any good this year.

our new furnace goes in this month and so hoping it will work for us for next winter..again.

even withouth the heat we managed to keep lettuce and other greens like swiss chard alive all winter in zone 4..but I hope to have heat this winter and hope to keep more things alive longer..have my peppers and tomatoes in it now and had some frost when it dropped to 24 degrees that did damage the tops of some tomatoes however..they are coming back from the stems and roots.

I'll post pictures of the other two beds and aquaponics in the rest of the greenhouse later. I have used pex under the other beds and heat the water from two solahart water heating modules that I recieved for free.

Nice. Did you put a controller/Tstat on the fan or just rely on direct PV? (enough sun to run the fan should mean enough heat to run it through the beds).

I am also interested in the aquaponics part and how you fit it all together. How big is the greenhouse? how much bedspace did you fit/cram in there?

Here is an update on my new, this year, greenhouse. And somethings that I learned or would do differently. Attachment 1 shows a free Craigslist find, it is a solar swimming pool heater that is supposed to lay flat on the ground and heat your pool. I coiled it and placed it in my hydroponic resevoir, it in turn is attached to the scavanged Solar Hart water heating panels on the south side attachment 2. The solar water panels are also hooked up to pex tubing that is run under the beds. Mid summer it really was putting out the heat and I have had to cover the panels to prevent overheating. No pumps just thermosiphoning for the heater.
Attachment 3 shows the north side and how I can roll up the sidewall.

So that's the exterior, since i can only have three attachments per post I'll show the interior and its components in another post

There has been substantial slump from the hay bales as the season has progressed so I continue to fill as I have harvested and replanted. Over the central bed a framework was built to hold hydroponics on the east end and allow squash tomatoes and melons to grow on a horizontal trellis held up by the frame work. the squash and melon plants were planted into tomato cages to encorage them to climb to the horizontal trellis allowing me to plant and harvest under the vines. beets,peppers, kohlarabi, daikon, turnips, beans are some of the plants growing in the understory they are doubly shaded by the greenhouse shade cloth and now the vines. Access to the beds is easy and adequate with the raise trellis.

The bilge fan vent works great under the bed in which it was installed however the slump that I didn't plan for did pull ot the exhaust ends and I had to develop a sliding collar to allow the vents to work and still fall with the decomposing straw.

If I'm not careful one chicken has learned if she is quick she can enter the greenhouse as i enter and leave the pen. The chickens love all the fresh green trimmings that come from the greenhouse since it is right there.

The squash in the center of attachment 1 is a bit larger than a football and supported by bird netting. I don't know if I have to do that so am doing it on 1/2 of the squash and letting the other 1/2 go unsupported.

I experimented with a couple of irrigation ideas, in the central bed it consisted of corrugated drain pipe on the straw bales, by flooding the drain pipe for several hours the straw bales loaded up with water and apparently work quite well in retaining water, plants remained hydrated for several days. The other two beds have been watered from the top one with a slightly buried soaker hose and the other with sprinklers. These two beds seem to be the same and need more attention than the subsurface irrigation when it comes to keeping the beds hydrated.

Hydroponics next