I got out my Irish Eyes seed catalog and on page 13 are plans for something I already knew but I like step by step instructions.
Grow 100 lb of potatos in 4 SQ FT!
You will need: 6 2"x6"x8' boards
1 2"x2"x10' boards
96 2.5" wood screws
2-4# of seed potatos per box
1 soaker hose
NOTE: you can use pine, cedar, redwood or pressure treated lumber that has been treated with copper sulfate which is non toxic.
Step#1--Cut the 2x2 into 4 lenths of 30"
Cut the 2x6's into 12 lengths of 21" AND 12 lenghts of 24"
Step 2 would work better if I could show you the pic; I would suggest ordering a free catalog from Irish Eyes Garden Seeds but here it goes;
assemble 4 of the 2x6's and the 4 2x2's with the 2x6 on the outside...it will look like an upside down table with the legs sticking up. You fill the inside with dirt and plant the potatos seeds. Coil the soaker hose and let the potatos grow until the plant is 12 inches over the top of the board.
Then add 4 more 2x6 boards on the outside....fill with dirt up to 1/3 of the height of the plant. Leave it grow the same as before.
There will be 6 layers. The instruction say to harvest from the bottom but that sounds like a pain. I say take out all the screws, dig through the dirt with your hands to harvest the potatos, and salvage the dirt, mix with compost and start again.
In TX it gets pretty hot. I say stack bales of straw around the outside to insulate and keep cool. Fire Ants might be a problem as they will see this a airconditioned condo. Treat around the outside to make entry unfavorable.
Storage is the next thing. Nothing stays cool at my house in TX. I don't run my a/c unless I am having a heat stroke.