Go this information off a site called "The Palm Centre" Bamboo in containers
The best formula for potted specimens:50/50 mix of peat-based compost and loam-based (John Innes no.2,3), the appropriate amount of slow release fertilizer (for example Osmocote), 25% sand or grit. Bamboos are vigorous growers, so to maintain healthy growth remember to add more fertilizer when the first application has been used up. Add top dressing at intervals until the bamboo finally needs repotting. When the bamboo has filled the pot, either repot into a larger container or divide the bamboo, replanting a piece of younger growth as the new plant in the original container. Mulch around the base of the plant for winter with ornamental bark or gravel.
Doesn't give the actual size of the pot though