The fundamental question is what you want the greenhouse to do. In my super short season, adding 36 days at the beginning gives me 20% more season to put to a good use. Not only that it should allow me to bring up 2nd year plants to market size by early June. Also the plants I work with are as winter hardy as they come; if I keep them a tad above freezing at night they will still grow. This all means that because of the short period I need to cover I can afford to pump some heat into the greenhouse, with a eye on pumping it into a thermal mass to regulate temperatures at a level lower than most people think about.
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The newer blankets are more water and weather proof. But maybe not PNW proof. And the PNW has greenhouse issues, namely not enough light and heat in winter. Even the Chinese method doesnāt work well if the sun never shines. It would ameliorate your occasional 20F freezes. But so does a cheap heater.
Iām venting heat in my GH most days all winter. Thatās because we have 75% sun in winter and minimum 10.5 hr daylight vs 8hrs and 20% sun in PNW.
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If I were to try to use a rootstock for dwarfing figs I would try grafting on to āLittle Miss Figgyā, it one of the most dwarfing fig varieties, and itās easy to get, although I donāt know how much of itās dwarfing effect gets passed on to the grafted on part.
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I have been doing a lot of thinking independent of the information on this thread, primarily because I think I missed it in my searches for āwalipiniā somehow, so I took the liberty of adding that term to the title hoping others will also find it in the future. Feel free to change it back if desired.
I have some irons in the fire to assist with a walipini style greenhouse. Iām hopeful Iāll catch that bus and have it installed by mid year next year.
Kind of parallel to that project, I currently have access to a few thousand feet of free piping I will be happy to save from the local dump, both for geothermal heat and tree tubes. Itās only 4" but basically unlimited amounts will make up for size.
Seeing the gabian baskets in the first video kind of solidifies that as a viable cost savings, although Iām considering bin blocks for the base of the structure without needing a foundation. There are a lot of people on marketplace giving away bricks and block too.
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I have been thinking about walls for a walipini. Having access to free/cheap IBC totes could be a game changer if I can get them set up for both water and heat storage. The wheels are turningā¦
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It is wild how many smaller pipes are needed to equal one large manifold pipe! Thatās where actual engineering is important. Also friction loss drastically increases with smaller size pipe.
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I have a feeling friction also increases with corrugated drain pipe, vs smooth. Iām not sure that just friction from going through smaller pipes is bad - the goal really is to suck as much heat out of the soil as possible, and that is done with contact and friction, no way around it. Iām fairly sure if one used bigger pipe, itād be less efficient at conduction.
Thereās so many variables, and I wish a university or someone with the funds would do a study on the many small variables.
In my part of the country, one can often have quite easy and cheap access to used aluminum irrigation pipe: Smooth walls, one of the - if not the - most thermally conductive materials ānormiesā like us have access to. I see it advertised used for $1 a foot often, which is on par with corrugated drain tile. Downsides: comes in 40 foot āsticksā (hard to transport), and mostly larger sizes like 8 inch. Though sometimes 4" does show up. And then of course you canāt really modify it with a box cutter. But thereās premade fittings. Not sure if itād hold up to soil pressure or not either, without the ribs.
I think the IBC totes are well worth exploring. Iāve been theorizing for some time that an āaquathermalā setup would be better than geothermal, from a cost perspective, for the bulk of people who donāt own their own backhoe (or have a friend with one that works for beer). As I understand it, excavating (and backfilling) the mass of soil needed to install those pipes is quite expensive. I keep thinking every year Iāll at least get a small test setup going, but stuff always gets in the way.
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I have around 6k hours running excavator and probable access to one for the expensive part. So with holes dug and pipes place at the cost of my time, focusing on the actual greenhouse and fine tuning the details in my circumstances is desirable. I know @fruitnut mentioned his āif I did it all over againā wishes above but Iām pretty confident that climate-wise and for my intentions different greenhouse tech would be appropriate. Texas is blessed with much more heat and sunlight than western PA.
My main thing is figuring out if simply running blowers all year long at certain temperature trigger points off of solar/batter would do the trick.
Then, using the excess energy, if any, as crypto mining or some other beneficial outlet, ideally not grid tied to avoid monthly interconnection fees. Itās more on self sufficiency and principle than the cost, although getting power ran from the pole would probably cost as much as the greenhouse or the solar system.
Read an article I think in Mother Earth News or New Shelter magazine in late 70ās about a large greenhouse with minimal energy costs. He built the base as a concrete basement maybe 10ā or 12ā deep with hi-density Styrofoam underneath and thick foam outside the walls. Laid a plenum and pipe system of schedule 40 with circulation holes wrapped with soil fabric. Filled it with inert coarse gravel and had short stem walls with horse manure piled against them, outside. Coldframe panels over the manure sloping away. Low greenhouse on the concrete āboxā, an array of flat panel hot water solar collectors next to it that pumped into the pipe system. He flooded the gravel with water for thermal storage, had concrete pads on top for walkway and bench support.
Covered outside at night and for hailstorm with a manual roll-up system of bamboo mats operated by a large crank resembling the ones that started your 1910/20ās car.
He said the only downside was the initial cost, I vaguely remember it was over $100,000 ; 1980 dollarsā¦
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Fascinating! Not the one I remember, mine was right after the giant natural gas price spikes of 1978/1979 so the guy was willing to spend big upfront money. Your article, and itās reference to Whole Earth Catalog sure jogged some memories. 
Those sunken greenhouses must have been a real movement, back then.
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Now I have to go find my mother earth news cd catalogā¦ I purchased the entire set as of about 10 years ago.
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The Mother Earth News website has a robust search function and have uploaded many articles from their old, old publication issues. I suspect that the article in question might be found in the other publication mentioned. The multiple search strings I attempted should have located anything that M.E.N. has up at this point and if they digitized it for the DVD-ROM set then I would expect it to in the database that I was searching in as well. Please let us know if you do find it.
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I was mainly reading Mother Earth News and gov. ag. bulletins on alternative crops in early 70ās. Itās possible it was a chapter in a book about off the grid and non-traditional ways of doing things. Kind of remember about 2, non-mason women constructing a circular stone schoolhouse using a central pole and rotating beam with a slightly curved plank on the end to continually set the stone, sand, and lime mix against. Sure canāt recall stuff like I couldā¦
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General greenhouse questions here:
I live in zone 9a or 9b, but get close to 7000 growing degrees per growing season.
Having said that, Iām wondering if it really matters how I orient my greenhouse - both long dimension wise and roof pitch wise. Iām more worried about keeping temps manageable in summer than squeezing out heat in winter. We only average a dozen or so freezes a year and rarely get below low 20ās even then.
Any thoughts?
Iām really liking the Backyard Discovery Zalie greenhouse. Not cheap, but wood with power hookup and thermostat controlled fan.
I am placement constrained on my 1/4 acre residential lot.
Iāve also thought of designing, sourcing, and building my own, and the engineer in me likes the idea, but that would take a lot more effort than just spending the money.
Any thoughts would be appreciated.
After thinking and researching, I think Iāll build my own similar to the one I posted about above. It seems itās easy to get the thermostatically controlled fans and louvers.
Iām now thinking of an exotic hardwood like cumaru or garapa.
I will still come in cheaper than the Zalie, but of course a lot more work and time to get to built
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What are you wanting to grow, citrus, mango?
Hereās a video I just watched from a guy growing citrus in a high tunnel near Waco.
How we grow year round citrus to feed our family and to sell at our own farmers market.
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For sure will use it for starting plants. Probably for winter for a few tropicals. I am not getting too ambitious as I am limited in space for what I can put in, greenhouse-wise.
As it is I will be installing this on top of a composite deck I have that isnāt completely finished.
This is the one I am getting
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Dragon fruit for sure. Should be able to move it in and out in winter if I use caster wheels on the pot.
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