Solar Earth Sheltered Mini Greenhouse

A small idea snowballed into something I can stand in by the time I am finished, I live in New England so this will be a challenge this winter without spending money on heating. I have a lot ideas on how to go about doing this, including a pipe and fan to draw air off the high peak and blow it under my soil beds I just need to start digging down 3-4ft and line the walls of the earth with wood...the rest of the frame is surprisingly strong. I will double the plastic walls with a 1" air gap between the two and as much glass on top as possible, if I can't blow the warmer top air under the beds it will deff be blown around them completely to keep the roots thawed with an additional clear dome over some of the beds inside the greenhouse. I am only 5'6" so I will be able to stand in it with a small walkway down the center, I want this thing filled with greenery good for winter blues too to be able to barley sit in the center walkway. Not sure what I am going to grow yet definitely broccoli and lettuces, some cabbage even though I personally do not eat it, not sure what things I can push with the cold season depending on what kind of heat I can hold with good circulation and some homemade sun heaters...possibly a tiny rocket stove when it's really cold which can be lit briefly every other day which would also raise CO2 levels which is good however burning some candles in a safe enclosure might be a more stable route.

Many more updates coming very soon!

There was a massive amount of rock right where I chose to dig haha at least it saves on hauling in rock for my thermal heat sinking floor, most of this rock will go right back in for the floor:



I'm about 3.5 feet down and need to go another 6" before I can install the wood earth retainers, I threw my back out today moving those rocks so I will be forced to take a break on excavation for a few days and focus on retainer fabrication:




If anyone has seen this video on GrowingWisdom he is in Massachusetts as I am, his is technically a walk in cold frame and I believe mine is about the same on a smaller scale. This one is 9ft deep on the tall side and 1/3 longer than mine by approximately twice as wide...mine will be standable but crowded/packed with eatables:

hey-
i like this =)

good luck with your project
will be curious to see how it turns out...

Thanks! I am determined to finish all ground work on deadline before the ground stays frozen, if I have to finish the top in the snow and shovel it out I will...it will dry out and warm up within days.


I dropped in the first earth retainer sidewall today made from scraps of sheet/ply wood screwed together with 1x3's all painted the same color (just a gallon of random indoor paint I had to help make the wood last a little longer in the dirt). Also I could not get those two large rocks out so I decided to bury them surfacing at floor level so I had to dig down 5ft before I dropped the rock in, I need to dig the rest of the floor out leveling it with the bottom of the board. I already have the retaining wall for the other side screwed together and painted ready to drop in along with the back walls that will go under the fence, I am still gathering wood for the front wall. Once the floor is leveled down to the retainer wall bottoms I will lay down plastic sheeting stapled to the walls (with slack) then lay foam insulation board down on top of the plastic sheeting, also if I have any left about a foot or more up the retaining walls from their base...after the plumbing is complete on the floor I can dump rocks back in and raise the floor of the entire greenhouse by 1+ feet it will not be a deep heat sink/storage but wide and with various size rocks made from different compositions this way some will store heat longer than others.



I am going to have to do something about the entrance when I make it to the front retaining wall, keeping a step or two inside is a waste of heated space (you can see the dirt square I left to step in and out on right now). I think the best option would be a step outside the greenhouse that will essentially be a pit in front of the door that I have to keep a board over to prevent filling with snow, and I will dig it deeper then the section in the front retaining wall I remove for the door this way it will not drain water into the greenhouse when it rains...sort of like a french drain in front of the door since it is below ground level

Israel O'hagan : Good luck, it will be interesting to see how this one turns out ! Big AL !

its a cool idea, looks like it will work out well for you.

some thoughts i just had- have you read about hot composting? rather actually, i mean, making a hot bed with mostly straw and manure...

i havent been gardening in a cold climate for many years but i would do this if i were...using tons of straw and also manure in the growing medium, fresh straw, so that as it break down it heats up and adds heat from inside the soil.

actually i have been thinking to do something like this, because i have just moved to a new climate that gets a lot colder and i am still getting to know the region. we will see how the new winter gardens i have been putting in make it. so far its looking ok, but most of the plants in there are just tiny right now and its getting colder.

but i am planning on using a lot of straw and leaves, and if i get inspired to get some manure somehow....not technically making a hotbed exactly, just using the straw and manure to warm up the soil a bit. already got a nice thick layer of leaves, and am trying to build up soil, so want to get some straw bales.

one neat idea that i would love to try out involves lots of straw bales. positioning them around the plants and making an enclosure out of them. then filling in the middle of it with straw, completely surrounding and covering the plants. this sounds kinda weird, but i think its brilliant, the plants will be kept warm enough, and the food fresh under the blanket of straw, one could store the harvest right in the ground under the straw this way. the cold prevents the straw from rotting right away, and the straw around it insulates the whole thing....

some plants would die, but many would make it, and even if they died the food on them would be preserved as long as its a sufficiently cold climate.
and when spring came you could un cover the whole thing and use the bales for creating hills and levels, and for mulch.

I think with all my research that this system should work perfectly, including plastic soda bottles painted black full of water hanging on the high end of the roof where the hot air rises to...they will absorb sun and radiate heat after dark in the same area as the heat sinking intake.

I have heard of keeping a compost pile inside your greenhouse if you have the room (I do not) but it sounds like you are referring to just adding compost to the growing beds. I can see adding straw to the top of my beds and allowing it to break down into the soil but even though I have access to bags of composted manure I can't see using manure inside the greenhouse wouldn't that make all my soil very acidic and change the pH?

I would not want my plants completely surrounded and buried in straw that is the point of a mini hoop-dome over the beds inside the greenhouse; much cleaner I do not want decomposing straw touching food I am going to eat that does not require cooking.


I really like this lady's greenhouses with all her free heating and somewhat complex systems, hopefully this will not be a dead link in the future: http://youtu.be/SBaUd7PKWUg

well whatevers clever =)
just adding some thoughts that came to me as i was thinking about it.
i'm sure as you have been visioning it and are obviously motivated to make it happen a certain way, that it will work out great for you....you know theres something to those ideas that we vision and have to make happen...i'm sure it will work out.

but yes- i did mean adding lots of manure and straw to the growing medium/soil...to use the warmth generated by these from under the plants, within the soil.

and totally this suggestion would require some experimentation and tweaking to figure it out good for a specific place. this can actually get too hot in some circumstances...but being surround by earth that keeps a constant temp, and being winter i dont think it would get too hot....it would just add some warmth.

and one wouldnt have to do it any specific way or go for the whole plan, and make a specific hot bed...you could just add straw and/or manure in smaller amounts and get a smaller effect, also hot compost in place, under the soil....to get a little bit of extra warmth. just using lots of straw and other mulch will add to the warming effect...and hot composting in place adds heat too...

some food for thought, anyway

I will certainly give it a shot, the only thing is it would be hard to turn the compost so it would just have to sit. I think composted manure is much less acidic and I can always add some of that to the straw.

In further detail the top will be entirely thin glass pieces from aluminum storm doors, one of the side walls will be wood and the back wall is wood as well (fence). The front wall and remaining side wall will be plastic, probably two layers thick with another 2 layers on the inside about 2" apart from the outer layer using the thickness of the 2x4 frame as an air buffer space. I can toy with ideas once it is constructed such as small computer fans to blow warm air into the buffer space between the plastic sheeting...small 12v motors could all be ran off a battery and solar panel.

This is an illustration of the greenhouse, the blue lining is roofing tar paper and the yellow within that is foam insulation board. There will be a false floor to hold the heat down for storage with a few inch gap around all 4 sides to allow warm air to rise against the walls forming a warm shield around the greenhouse like invisible walls of heat. One change I am implementing is the use of some water in my heat sink instead of entirely rock since water holds three times the thermal energy as rock does, I will use the rock to support the false floor though so the rock level will be higher than the water storage containers and with a few drops of bleach I think thick plastic bottles will be fine if surrounded by rock carefully.



One thing you can not see in that illustration is the plumbing system to sink the heat, starting on the right side centered the air rises as it gets hotter and travels along the sloped roof in the strongest sunlight until it reaches the peak against the fence side since heat rises. The very warmest air in the greenhouse gets sucked into that black tube by a DC solar powered fan and pushed under the false floor where it is released through a tube with holes in it that runs down the center of the floor, surrounded by rock and containers of water that store the thermal energy. The trickiest part that I will have to field test is the timing of the fan so that it does not suck cold air off the ceiling at night however since heat rises I would think that is where the warmest air would be night or day anyway and I still need air moving through the floor to release that stored heat, I think people only worry about the system shutting down at night if they are just blowing the top air under their beds and not storing the heat down there.