Well in my personal opinion...... They don't each NEED a gallon! Up until recently I've just been giving my babies ONE personal water bottle each. and my biggest one is about 8ft tall! Recently I have been giving them each one 1.5L of Poland spring, but luckily its been raining alot so i don't have to go out there as much. I have 12 so I just go with a partner. 6 bottles per backpack. My are directly rooted into the soil, i didn't put them in a bucket and put in the ground. Remind yourself... It is a WEED, and once grew wild all over the place with nothing more than mother nature. I believe if you don't water them as much, the roots will spread and search for water.. which in the case when you to water or get a good rain.. when the surface dries up, there is still moisture down below that the plant can catch. I'm no pro! Just my 2 cents =P