Frequency depends upon the type of plant, soil, etc. The amount should be sufficient to run through the drainage holes of the container. Daily inspection will indicate if pests are present. Spray at full strength with pesticides recommended by a local garden center. County extension agents are helpful in determining correct pest identification and proper control.
Spring is the optimum time to transplant before the new growth begins.
First, was a rather serious problem with a 30 year old Juniper. The tree started to turn yellowish and wasn't putting on new growth the way it should. After trying everything else, Dr Armstrong tested the pH level and found it shockingly low - 5.5 instead of an expected 7 or 7.5. Since Charlotte water is normally about a level 8, this was not an expected occurrence. He is now giving his trees a modest dosage of lime and the Juniper is starting to improve.