What would you suggest, wood,clay,terra cotta or ceramic. Jerry
Whats best container material for Japanese maples
Unsealed wood or terra cotta will be about equal, with the terra cotta getting a slight nod because of somewhat greater gas permeability. Unglazed clay = terra cotta. Ceramic and plastic are about equal because neither are gas permeable. Try to select light colored containers or shade the darker containers. Root temps should be kept below 80*, and the permeable containers offer a little reduction in soil temps because of evaporative cooling, and the light colored containers limit passive solar gain.
Al
We have several JM's and they are planted in large, 24" diameter ceramic pots. I use the ceramic because it gives me some wiggle room on watering. If they were in clay they would need to be watered twice a day down here and your climate in JAX is almost identical to mine. The soil in plastic tends to be hotter still so I do not use plastics although I do use those styrofoam pots as they do provide some insulation for the soil.
Early this morning I took my brand new digital kitchen thermometer and checked the soil temps in various pots around the garden. The temps at 8:30 ranged from 81 to 83 with no significant differences between pot material or pot size. I thought that was interesting; perhaps later in the day I'll see a greater difference. The JM's would love a lower soil temp, I am stretching the window on them. Even the water is hot this time of year. The municipal water temp was 84.5 and it will get hotter as the day goes on. My rain barrel always stays in the 89/90 range this time of year.
Good luck with your JM's. A shady spot and drip irrigation really helps no matter what you decide to plant them in.