Going from 1 gallon to a 7 gallon container is a big jump. You will need to be careful for a while about fertilizing. When fertilizer is applied to the medium it is removed by the tree's root system. In your case the root system is only located in the center of the large container, so the roots cannot absorb (remove) the fertilizer on the outside portion of the container. Therefore, with each consecutive application, the fertilizer level will continue to build up, and build up, and build up. Eventually the fertilizer level will reach toxic levels. Therefore BE SURE to thoroughly leach the container with clean clear water every couple months, untill the tree's root system has pretty much filled the container, or your tree will surely get into trouble. - Millet
