The majority of home made sub-irrigated grow boxes are made from two 14 or 18 gallon Rubbermaid tote boxes.
These sizes aren’t big enough for Ray Newstead, an electrical engineer in Campbell, CA. He has become a gung ho advocate of 31 gallon grow boxes he calls “EarthTainers”.
The EarthTainer is well documented on the web. This is an article about Ray and this is his detailed description of making the boxes on GardenWeb.com. If you have doubts about whether these grow boxes work, his photo set is well worth reviewing.
These 31-gallon planters have a 10-gallon reservoir, which is significantly larger water capacity than the smaller versions. The last time I priced theses boxes the 18-gallon size was $7 and the 31-gallon Roughneck tote was $12. The larger one is 8” longer, 4” wider and just 1” deeper.
One box instead of two
Note that most of the DIY boxes, including Ray’s, are made from two tote boxes. The Rooftop Gardens Project design uses just one box and in my opinion, it's easier to make. All you need is a box cutter or sharp paring knife.
Where are the mainstream garden sites?
Obviously these sub-irrigated planters work extremely well but you would never know it judging by the lack of information on the “mainstream” gardening sites and more popular gardening blogs.
The editors, writers and bloggers are either rather ignorant of current events or have some unknown bias. I can think of no other reason. Can you?