Sunken greenhouse

[clarkinks]

Have built regular small greenhouses which, like a hot house, are great for things like lettuce when unheated. It is not very easy to control temperatures. To get around some of the challenges of greenhouse temperature fluctuations, there are people who build into the ground

Couple Builds a SUNKEN GREENHOUSE for $4,500 — Ep. 125

Insulation can be used under or on the sides of concrete. We used it and footings under my house, which helps

DIY Geothermal Greenhouse Part 4: Earth Battery INSTALLATION

Greenhouses are not always easy. This is a reality check for those of us in Kansas. His problems are our problems with things like pack rats

Sunken Greenhouse Tour 2020: Failures, Progress and Hope for the Future!

The more we spend, the better the greenhouse, but at some point, we want a return on investment. Geothermal is an option, but saving money is also an objective.

Greenhouse update (Nov). Insulation, geothermal heating and cooling, and more

There are people with great ideas, but im extensively researching ideas before i try again. Learned from my past failures

How To Heat A Greenhouse For FREE

Geothermal takes lots of digging and that equipment is very expensive right now

Greenhouse in the snow - Ingleside, Ontario

[Richard]

@clarkinks

earth-insulated ≠ geothermal.

[clarkinks]

@Richard

I’m aware of that. The idea of many of these greenhouses is to use both options. See this link from 2018 Geothermal orange grove! Heavy yields! . There are many ways to do geothermal, and many i dont know, but others i do https://growingfruit.org/t/geothermal-heating-for-a-building/51435

Before i build a project, i make sure i know a lot about it. I’m not there yet with geothermal for a greenhouse.

[DroppingFruit]

I was inspired by greenhouse in the snow style, contacted various people in that field. In the end because of shallow bedrock and wanting a lean-to style where some underground drainage exist I went with a simple above ground polycarbonate style 5mx12m, 4m high at the wall.

I would rather that I spent more time and dug it into the ground inside, I still can dig 50cm deep easily. I also have some cracks to fill etc, Even without it fully sealed up in winter it only got to -3 C (28f?) in the front and -0.5 C under fleece against the house wall. outside min was about -15C (5F).

Mandarins are still fine so far so good! I will seal it up better in the summer and i have a heating cable that i will use in emergency but also graft trifoliate rootstocks onto the mandarins and lime.

[clarkinks]

@DroppingFruit

Very nice design. I can’t wait to see you picking oranges!

[DroppingFruit]

I should have a lot of figs and grapes this summer with maybe a handful of mandarins, 2 fruits are almost full size. I finished it last summer, the figs grew a lot and put on 50 fruits that did not fully mature but still sit on the plant, so this summer the young figs will really explode and ripen well.

I am looking into planting a dwarfing rootstock for the figs. (‘Bensonhurst’ and ‘Chicago Hardy’ varieties?)

I am thinking to build another one as a lean-to against our barn 20x6m Where I will just make a polycarbonate roof and cement pillars to support it/hold it down. Making the walls with square hay bales covered with fleece. This way it is secure from strong winds, can easily be sealed and ventilated by removing a wall or two of hay bales which can become mulch and I can minimize expenses. I already have 10,000L of rainwater collection set up there…

The first one cost me about 8000 euro cuz the wood.
The second one, I milled our own wood, reduce wall and cement so in total should cost about 4000 Euro. I would keep the second one flat with the ground also so i can drive a tractor in the removable wall if I decide to till or deliver compost… I would mostly use it for figs, grapes, citrus and tomatoes if I want to try and make the money back that I invest.

After giving up on maintaining 32F to grow some tropicals, I don’t care to put in geothermal etc. Ripening figs and Citrus which will survive to -5 to -10c is easy to manage with cheaper wind-storm-proof-greenhouses.

[BlueBerry]

Nice looking greenhouse setup!

[oscar]

@DroppingFruit

I am looking into planting a dwarfing rootstock for the figs. (‘Bensonhurst’ and ‘Chicago Hardy’ varieties?)

figs
I am curious. I haven’t heard much about dwarfing rootstocks for figs.
In my experience Chicago Hardy (if i have that fig and not a misnamed one) and other cold hardy cultivars aren’t that dwarfing.

All figs if seen though, don’t seem to need a dwarfing stock to produce. Every fig if seen can be pruned into a bonsai and still produce.
I generally prune 1/2 of 1y old shoots off. Leave the other 50% for breba.

Or if it is a main crop that can ripen in my growing zone. I prune for lots of growing points, since they tend to come on sub 1 year old wood.

I leave very little wood older than 1 year around.

water as thermal mass / heat buffer
i am very curious about your 10.000 liter rainwater collection. Is that in barrels or IBC? or more of a pond like storage?

Either way, water has a good thermal mass, especially in that amount. Having that water storage inside a greenhouse can stabilize temperatures a lot. (especially at night during a radiative freeze, would be your main source of keeping it above freezing)

is your barn south facing? (north west orientation)
That especially matters in the winter if you want to keep your greenhouse warmer.

I’m very interested in these semi-underground greenhouses. And want to build one some day. They are also sometimes called earth ship or passive solar greenhouse. In china they are used in somewhat larger versions and scales for winter vegetable production.

Lots of physics goes into passive solar greenhouses. Angle of incidence not only determines surface area of incoming sunlight. by affecting the Hight. But also determines transmissivity. And the ability for condensation to run down.

orientation for “classical” greenhouses is less critical. For passive solar greenhouses you want them to be east-west length wise. And a narrow long and high design gets optimal solar incidence.

[DroppingFruit]

I had heard that grafting onto a dwarfing rootstock could limit the size of the fig for a greenhouse. But I am new to figs. I understand the technique is to tip prune them in June to stimulate fruit formation. Then reduce excessive growth to further focus on fruiting. Not enough experience with them yet. When do you prune half the growth off for brebas, late summer?

I have the greenhouse back wall in this canopy plan Very dense with Figs as the tallest, Grapes mid level, and citrus lower level(shaded in summer).

I am 9 years in tropical Horticulture and the last 3 years (not so far from you!) in Germany climate so I kind of have started over with plant skills and research.

The second greenhouse, The IBC tanks are stacked 2 high, 5 in a row currently outside (I have considered moving them to the inside) the barn which has a south facing wall. just has strong winds there.

The roof angle is basically the same game as for solar panel alignment imo. About 45° I’d say. You can aim for more steep but then the structure changes into a south wall or bent roof.
Solar angle for here is Winter16° Spring/Autumn 39° Summer 62°

My first Greenhouse is a bit too steep leaning into summer angles but it wasn’t an issue for the tomatoes or other plants and last summer was pretty hot.

I like the cheap Chinese designs but I think the wind here would destroy the foliar and i have existing buildings to utilize and these are mostly for fun / personal fruit supply.

I did not predict the condensation run down, I will improve that and the roof angle on the second greenhouse. It would be fun to make it in ground also but I am not sure if I will because of the retaining walls and more work needed, I think with ventilation cooling is enough and for what I would grow safely anyhow should be hardy enough.

Mostly I just want to get to zone 7-9 inside the greenhouse for the figs, citrus and grapes. I don’t know of anything that really inspires me until i maintain above freezing for pouteria, jaboticaba, starfruit, miracle fruit… but then i can also just vacation to my tropical property with tons of that plus jackfruit, marang, bananas, etc.

I find it also interesting how much a greenhouse can be auto irrigated/ventilated without electricity in the even I am gone for a winter and people don’t manage it. I think gas pressured air valves and rainwater overflow into drip irrigation or a larger drainage pipe delivering flood irrigation to avoid clogging issues.

Another aspect is the glazing used. I used triple wall polycarbonate which reduces the sun penetration so a more flat angle can be more acceptable and better temperature retaining ability.

What are you guys thinking to grow if you keep it warmer in a sunken greenhouse?

[clarkinks]

Love this tutorial for tbudding figs by @fruitnut. My fig bushes always stayed very small at 6’ or less. Would pinch mine back frequently to cause fig formation. Im not keeping figs at the moment. We nearly made ourselves sick eating so many.

Cold hardy figs

Trying to learn more about cold hardy figs. Ive been growing brown turkey in the ground several years and im trying chicago hardy this year. I know the people who are into figs frequently have 100+ different cultivars. What are some other cold hsrdy varities? We are zone 5 Kansas and we do expect them to die bsck to the ground each year.

T-budding tutorial

I’m new to T budding figs. They seem easy so far and the wood is big enough to show well in pictures. Too close on some so not focused but still visible I think. First a couple of key points. Don’t even try if the bark isn’t slipping well on the rootstock. If not slipping it’s hard or impossible to insert the bud cleanly under both flaps of the T. Not cleanly under and success falls thru the floor. Get bark slipping by watering at least a week ahead of budding. Also cut back the rootstock in w…

[fruitnut]

If I built another greenhouse it would be sunken at least 3-4ft and facing south. The north wall would be insulated or earth bermed with large exhaust fans in the north peak. The east and west sides fully earth bermed. The south would be the wet wall. Roof double layer inflated woven Solarig or Palring poly. It’s by far the best covering for the money IMO. So basically the only covering would be the roof about 45ft by 40ft. That’s the right size for two 36 inch exhaust fans in this climate. Wet wall about 4ft by 32-36ft.

In my climate that would allow 800 Utah chill hours in 45 days in winter. The rest of the year would be 80-95F by day and 50-65F by night. That would be perfect for stone fruit, citrus and hopefully mango. Plus nearly anything else that can be grown in California.

The main reason most greenhouses fail is because of inadequate heating and cooling systems. So they complain about too hot in summer and too cold in winter. I don’t understand spending money on something that doesn’t work.

My current greenhouse will do the same as the one I just described but probably costs twice as much to heat as the buried/bermed version.

This climate is 75% sun all year around and at 30 north has good sun even in winter. Any sunny winter day requires cooling or it exceeds 100F. The buried earth tubes would work good for heating in winter but won’t cool enough in summer because our ave annual temp is about 62F vs 52-55 in Nebraska, Kansas, and Colorado where it can both heat and cool.

Just remember that the citrus in the snow setup is very restrictive in that the climate in there is what it is. You have little to no control over chilling or temperatures. Plus most importantly to me very little growing area and a small light footprint. It sounds great because you can grow citrus up north. But citrus doesn’t require much light and tolerates long cool winters. They grow citrus in sunken greenhouses in Russia. But how good is the fruit and how much.

I want more control and a bigger growing footprint. That requires active heating and cooling. Cooling with a wet wall for a 45x40ft GH costs maybe $1-2 day. Heating to give the 10.5 months of really warm growing conditions in the sunken GH would probably be $500-1,000 a year here.

I can do my current greenhouse for stone fruit with a heating cost of a few hundred a year. I’d just heat a lot less and have a bit shorter growing season.

In the CO to KS area if you forget about mango and maybe citrus you could grow stone fruit pretty cheaply in a GH. Stone fruit is as good tasting as anything and properly grown better than citrus and maybe mango. The way to grow stone fruit cheaply is to only heat enough in winter to keep the plants above the critical freeze temperature. In the fall ease the trees into dormancy until they drop their leaves probably late Nov. So nights at 37F in fall until they drop their leaves. 37 is optimum chilling temperature. Days below 60F with evap cooling if necessary. Dec-Febr hold 0F at night and below 54 by day. In spring and summer go to 34F at night to avoid freeze damage during bloom and let it warm to 90F by day. Your season would be two months longer than outside, maybe more. And you never miss a crop to freeze, wind, hail, disease, birds, coons, and so on.

[Spartan]

Where I work in Wisconsin, we overwinter many small plants in poly houses. Not heated so had some loss due to root injury some years.

Then the crew built sunken hoop houses into the ground with concrete. Major improvement! We heat them only slightly when needed to keep the roots safe on cold winter days. Way less loss.

[zendog]

This one isn’t sunken, but is pretty impressive considering where he is using it.

Passive Solar Greenhouse Webinar

[fruitnut]

Night time roll down insulation would be a real game changer. I’d like to know more about that, cost, R value, etc.

[zendog]

You can see now he’s teamed up with a tech company and is using bitcoin mining with water-cooled computers, putting the heat from the water cooling of the computers into heating the greenhouse. Definitely pushing the envelop.

Passive solar greenhouse+Bitcoin mining=Tomatoes in extreme cold climate

And here is another one on the insulated blankets on a single wall greenhouse in California. Probably worth giving him a call if you’d like to figure out costs to give your greenhouse a comfy winter coat.

Insulated tunnel greenhouse in Southern California

[RedRam]

Another good search keyword for sunken greenhouses is “Walipini” (the word is apparently native south American in origin?). They also tend to be very basic and economical in many cases, it seems like. Versus all these youtube videos of people who spend 20 to 40 thousand (and up!) dollars to grow a couple baskets of greens in the winter in their fancy geothermal setups.

I’ve been watching a lot of these geothermal greenhouse videos, hoping to make something similar (but much more economical) one day. The biggest mistake I see amateurs make, is not properly sizing up their trunk piping to accommodate all the branch pipes. If one is using for example a dozen 4 inch branch lines, then ultimately the collection pipe is going to need to be probably 16 inches diameter at least. I’ve seen so many people that collect like a dozen 4" branch lines into a 6". Which wastes about ten of those branches, along with all the digging. I think one of the big downsides of geothermal setups is that they’re nigh impossible to modify cost effectively after the fact. So the margin for error is slim. Add up those cross-sections properly!

[fruitnut]

@RedRam

Another good search keyword for sunken greenhouses is “Walipini” (the word is apparently native south American in origin?). They also tend to be very basic and economical in many cases, it seems like. Versus all these youtube videos of people who spend 20 to 40 thousand (and up!) dollars to grow a couple baskets of greens in the winter in their fancy geothermal setups.

The Chinese greenhouses aren’t sunken. Those people are poor and looking for the most cost-effective way to make a living. What the Chinese style GHs are is earth bermed or highly insulated on the north, east, and west. They also have a big light/heat catching surface, which equals more growing area. Then the key factor is insulation at night.

So the Chinese lesson is a large light/heat interception and low heat lose at night.

My biggest hesitancy with the “greenhouse in the snow” setup is a small growing area that goes along with a small light interception. The Chinese method improves on that.

I think the Chinese style will be available soon. Mainly the removeable insulation.

I think a Chinese style GH would work great here and in the KS to CO area.

It’s actually similar to the way I heat my house. I’ve got a sunroom on the south side of my house. When it’s sunny outside I open the door to the sunroom. That heats my house by 20-25F from 9am until 5pm. At 5pm I close the door for the night. My furnace didn’t run last night and won’t very much the rest of the spring.

[RedRam]

@fruitnut

The Chinese greenhouses aren’t sunken.

Sorry if I made it sound like I was responding specifically to videos in this topic. When I said “all these youtube videos” I was referring more generally to the many youtube videos out there on youtube of people spending tons of money on greenhouses (especially geothermal ones) that seem rather unproductive. I was not referring specifically to videos in this topic. I should have been more clear on that.

I do find it surprising there aren’t more kits available out there that are more specialized for year-round, low-cost setups. It seems like there’s not much between generic high tunnels which are sun direction agnostic, and full-on custom built setups that are asymmetric to account for sun directions on the south and winter wind insulation on the north. There’s sun/wind agnostic with roll-up sides, and that seems about it for middle ground. Greenhouse in the snow is the only kit I know of that acknowledges sun/wind, but as mentioned it’s not very large, and the few videos I’ve seen of them being built, it seems very clunky to assemble.

I’d love to see a kit that has the asymmetry to address sun and wind, has a roll-up low south side, and has a clerestory for high ventilation. It seems like it shouldn’t be that hard.

[fruitnut]

@RedRam

I’d love to see a kit that has the asymmetry to address sun and wind, has a roll-up low south side, and has a clerestory for high ventilation. It seems like it shouldn’t be that hard.

I wasn’t taking exception to anything you said. I think we’re pretty much on the same page.

I see a business opportunity for a enterprising young person selling Chinese style greenhouse kits. It works in China, it worked at -40C in Canada, and it works in southern CA. But as usual I’ve got a plan to build an earth bermed version for cheaper. All I’d need is the insulating blanket and a roll up mechanism.

[Bradybb]

It might be beneficial if the blanket was made of some waterproof material or does the outer poly provide some R value also?