I'm STARTING what will be two walipini, and have water table issues so I'm doing massive
berm to help deal with the 'tie to the earth' and keeping things where I can handle the occasional back-soak issue. My soil is pretty close to adobe clay, with blowsand. Being that...
I'm aiming for 20x75', and two. One to be more of a four season 'abode' with my citrus and zone 10b tropical (fig, date, and various colocasia and alocasia); and a
RMH for supplemental winter heating as a lot of those frown at 50f or lower. I also want to keep a few wormboxes and some
aquaculture in there (spouse is into fancy goldfish). I spent a winter in a freestanding greenhouse shell inside my shop, and kept a two stage goldfish setup to provide 'used' water for watering, and kept a reservoir of a lift (350 gallons) of 'seasoning water' (heat reservoir and to degas as it was
city water supply). Reservoir provided water change water, used fish water was used to water plants (some under
lights). I wish to expand onto that.
Other walipini will be mostly for food propagation, and for starting small plants seasonally. I'm told a 75x20 can provide for a family of four to six. That one will also have an
RMH. My biggest costs so far will be the insulating blanket for over the plastic. I sourced lifts that never had pesticides in them; posts, poles, and beams to build the cap structure; saving for my sandbag bags right now to do earthbag inner walls, and for the greenhouse sheeting for the cap.
Long, but back to topic. I fully plan to have at least one integrated with fish as part of the system, to produce nutrient enriched water for the plants. Something to eat would
be nice but I'm afraid hubby's hobby means more decorative. However some of the plants will be eaten! You might narrow your walipini some, I'd say it would take structural steel to span that much, Jim. Literature and such that I'm referring to are doing the 20 or so foot wide, and I was able to score old telephone poles and some old barn beams to build the capping with, I will have some central support posts going down the middle. Let me know how you're doing Jim, Kevin, and the others! (yes I'm blessed with a quarter acre facing the sun and it has mounds of fill dirt already to begin the back banking. I plan to terrace that for growing small
trees and seasonal plants...)