a good rule of thumb is abouta foot for every gallon. but it's easy to get them bigger. a four foot plant in ten gallon bucket will give it plenty of room. good luck.
yah, its five gallon. I can yeild up to an oz in one gallon at 3.5 feet tall (at the most). I want to do an outdoor grow with like 5 sativas bushed out and 3 feet tall in 5 gallon pots.
so when you see people do the bucket in bucket system, is that aways necessary? when they drill bigger holes in the bottom and sides of the first bucket and slide it in a second one.
sounds like ur talking about either a wick system or a reservoir system. drainage is important, as is making sure the roots have plenty of air. other than that, there is no real reason that a plant must have a reservoir or a drain hole... more care is just required when watering it.