This plant was recommended to me by one of our local garden shops. It is planted in a very large concrete planter and for several months has done beautifully. Now, we have had a few cold spells and the leaves are brown at the tips and does not appear to be very happy. It is for Zones 7 - 9.
I'm guessing, since I can't see the plant, but I'd look at two things.... one, we haven't had a lot of rain, but there's been warm days and drying winds..... this plant doesn't like to go dry.... that could cause your brown tips...
then, two, most evergreens around this area prefer a soil that is on the acidic side.... living in a concrete planter, the soil may have changed pH toward the alkaline side from leaching from the concrete... then, I'd try using a good acid fertilizer like Miracid for the growing season and something like the following for the cool season....