THANKS FOR THE LINKS.
I have a mostly passive raised tomato bed this winter that has done fine in terms of keeping the tomatoes alive . . .
My God-seeded cleverness went along these lines . . .
North, 8’ back wall of the 13’ X 2.5’ block raised bed . . . 4 block high south and East and West sides of the bed . . .
5 10’ long 4” PVC pipes buried in the bed for heat storage;
2 6” PVC pipe uprights . . . one on the West end houses the pond pump that pumps water through 250’ of black garden hose arranged on the inside back wall painted dark blue—I hate black. The other 6” upright receives the output from the 250’ of black garden hose. and connects to the top of the buried back and forth 5 4” PVC buried pipes filled with water.
The West end upright is not sealed. I add water every month and a half or two as it goes down about 8” to a foot in that time from minimal evaporation.
I didn’t get the poly carbonate glazing on top of the verathane coated redwood framing before winter hit. So I wrapped the outsides of the block walls in a couple of layers of foam board insullation wrapped in a couple layers of 6mil plastic sheeting.
Got the poly carbonate 3 layers thick on the East and West ends. Got a couple of the 3 doors mostly finished. Have bubble wrap on top of the single sheeting parts finished and on top of the first layer of sheeting on the rest of the top and on some of the south sides—probably most of the south sides and at least a layer or two on the top between layers of plastic sheeting.
The temp inside has not gotten lower than 40.3* F.
It has often gotten up to 120*F during the NM days. Not good for tomato fruiting—blossoms don’t pollinate above 90* and fruit doesn’t set below 55* at night! LOL.
But the plants have remained vigorous growers.
LOL. Given that the doors are not multilayered poly carbonate yet . . . I end up cutting through the Gorilla duct tape and plastic sheeting every couple of weeks to water the bed then retaping . . . the condensation is incredible inside and seems to help keep things from drying out very fast.
At least come full spring, the plants should be all ready to kick off a fruiting season quite early.
What would I change? I might make the bed 3’ thick front to back. Would get the polycarbonate done before winter! Would probably do 3 layers and maybe 4 on top of polycarbonate with silicone caulk between the layers for an air space.
Want to make 3 or so of the roof panels hinged or easily removable.
Might try and make a couple of light bulbs inside where they don’t have a problem with condensation drips.
Would make it so I could water without unsealing it, if needed. Though finished well foam sealed doors might make that a nonproblem.
Not sure how to fix the wide temp extremes with a passive setup. Venting during the day would help on the high end but dissipate heat storage.
Condensation has to be taking a lot of heat out of the equation, too.
Anyway—has been fun and I think such a design has some promise in our kind of climate. But might not be the wisest setup for tomato fruiting. Might be great for some root crops. Don’t know about peas and beans.
Pond pump is on a timer to come on in the morning and off about 16:00.
Anyway—FWIW.
The 6” west end upright is not sealed but it has a cap on it with a hole for the hose from the pond pump beginning the 250’ of garden hose bit . . . and the hole is duct taped over pretty well but not a total seal.
There’s also a temp probe that goes down in that upright to almost pump level.