Underground greenhouse (Walipini) possibilities

http://wakeup-world.com/2014/02/13/300-underground-greenhouse-grows-produce-year-round-even-in-severe-climates/

Has anyone made something like this? It really appeals to me because I've been wanting to make an insulated greenhouse here in Portland ever since I saw Jerome from CRMPI speak.

I'm really curious if us PNWers (I believe John S. likes to say Mossbacks) could grow citrus or other usually difficult/impossible fruits in something like this? What else would it be good for? I'd use the earth from the excavation to do some Cob projects, so no worries there...

Thanks for helping me brainstorm!

Cheers,

-joe
urban farmer, SE PDX

I built one in Wyoming. Dug out the side of a hill and built rock walls up the sides. Made an A frame with wood from a house teardown.
Old door for entrance and old windows for roof vents.
Only thing I bought was the fiberglass sheets for the roof.
Worked awesomely!

Miles Flansburg wrote:I built one in Wyoming. ... Worked awesomely!

Nice, Miles! Great to have a lush jungle in zone 4! Looks well constructed too. What did you do for drainage?

Cheers,

-joe

I didn't have that problem. Dry area.
But the side that the pictures were taken from was level with the surrounding ground. Any flooding would have just run out the door.
Mine was only "underground" on three sides.

There is or was a citrus tree in Portland that survived many years, I'm not sure if it fruited. They cheated a bit as it was under or near the steam boiler output. I'm not sure about growing it in the open. A heat scoop will help preserve the plant but making it fruit is tough. My thought is to have a small citrus in a large pot on rails that I can move into a greenhouse in the winter and outside in the spring. No proof on the concept yet.

Our greenhouses are aboveground, attached to and heating our houses. We remove them in May and reattach them in October. So I'm planning to get some Meyer lemon plants, and try both keeping some in containers that we can move indoors for the winter and outdoors in summer, and others in the ground int he removable greenhouse.

I've actually been contemplating a variation on this.

A trench dug just wide enough to allow the target plants [I'm thinking 10-15 foot wide pomegranates and citrus, perhaps a few more exotic subtropicals as well [along with guildmates under their canopies], in small clumps by species, say 3 cultivars in a row of species X, then 3 of species Y, etc] branches to spread well, running east-west. The south side is sloped in to the trees at an angle shallow enough to permit full sun for the full duration of the ripening time [which is a good reason to avoid winter-fruiting citrus, there are cultivars out there which ripen during the normal early autumn months. At my latitude I certainly wouldn't want anything that would need ripening after Halloween.]

Above them is a reflective insulated ceiling of some sort, on hinges to change the angle throughout the growing season, situated at an appropriate angle to funnel additional light into the plants during the start of the rainy season as they're finally ripening, giving somewhere between 150 and 200% of the actual sunlight coming through the atmosphere to the plants.

With the right cultivars this setup may not be necessary, I'm going to be experimenting directly with simple microclimate hacks first but given our limited autumn solar gain I'm certainly having my doubts. My best bet is getting the very earliest ripening cultivars I can get my hands on and doing the microclimate hacking to punch our ~75 degree average summers up into something more comparable to ~90 degrees within the growing space of these particular plants, so hopefully they'll ripen before the mid-september cloudcover sweeps in.

Sounds interesting, let us know if you're going to do it, as I'm sure some of us would be interested to see it and/or help with the install. Another option I'm considering is outputting my (future planned) RMH's exhaust into this new greenhouse. Steam + CO2 + a little waste heat = great for tropical greenhouse. In the 10 year plan is a sauna that could have its exhaust redirected into the greenhouse...

-joe

Yeah Joe, Miles has a pretty big advantage over us with those clear-sky winters [and possibly a bunch of snow reflection as well.