The potential of hydroponics is far to appealing to ignore and apply to bonsai. Not so much for a finished product but for recovering trees faster from collection or hard root pruning. And for pre-bonsai material.
If I can apply this to yamadori trees at the time they are collected this could drastically reduce the time it takes for the tree to go from mountain to show. From 10 years or so, down to just 4.
The current thought on substrates used for bonsai is almost identical to hydroponic growing mediums. As well as the use of pond baskets to encourage a denser root system. A combination of pond baskets and the flood/drain watering 2 or 3 times a day will encourage trunk development for smaller trees and speed recovery for yamadori or field-grown trees.
When considering the types of trees and the individual needs I believe that I can separate them in to two broad groups; Arid and "Wet." Arid trees are ones that are very drought tolerant and can have completely dried root system before watering again. Wet trees are ones that are native to rainforest and temperate zones, that won't tolerate drought for very long at all. In their current pots this means little to watering cycles, since nearly none of them are planted in the same substrate. Arid group would be cycled twice a day during spring until late-fall and every other day during the rainy season in winter . Wet group will get cycled three times a day from spring till mid-fall and once a day during winter.
Will start with some smaller mallsai in small pond baskets, and cuttings.
I will have to start the build by Christmas
Inspired by (also, refer to):
Feeding, Substrate and Watering by Walter Pall.