Name: Anne Summerville, SC (Zone 8a) Only dead fish go with the flow!
A drip line is good - when I had them I used half the recommended amount of a monthly evergreen shrub food (don't remember what kind) every 2 weeks and they were in full sun for 6 hours. Your biggest problem is that it sounds like they aren't getting very much sun which can definitely have an affect on growth rate.
Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.
Douglas Adams
