hey there, wow, 5 footers!!! you said in a 2 gallon buckets on those two. what containers are the other ones in? do you change all the nutes at the same time all together? because i think that the two that are behind are what you said...root bound. AND because it is such a tree and only 2 gallons...wait, i'm assuming you are hydro and not dirt right? but with such a small buckets of 2 gallons, i would be changing that one over maybe 2 times a week as the nutes will be used up way for faster than the other ones. what method of growing are you using? don't want to write more until i know what i'm talking about LOL