I'm not sure about his style of gardening
, so I can't speak to that specifically. However, I do know of people
planting trees by seed in clay cubes in arid regions without watering
and the trees have sometimes made it.
As for tree spacing, that's more complicated from what I've seen. Sometimes people get away with spacing trees closer together. The trees adapt as they grow up and are fine. Yet sometimes overly dense plantings cause the trees to be stressed out and compete too much for resources like water. In the Pacific Northwest, for example, the summers have gotten drier and hotter, which has stressed the trees more. Personally I would go for a planned spacing just to be sure, but plenty of people are more experimental and it works for them