I live in Soquel California, 90 miles south of San Francisco and 5 miles from the ocean. About 6 months ago I planted 24 Thuja Occidentalis 'Smaragd' trees that I planted about 24" apart. The intent was to hedge a small area on our little horse farm. 12 plants face south and another 12 face east. 2 have died and the other 22 have turned rust on the sun facing side but are green on the side away from the sun. I am quite concerned. Thanks a million for any help.
Can you post a photo? Chances are they'll be OK, the foliage often does get a bit bronze-toned on the sunny side in winter. Turns green again as the spring progresses.
"Rust" sounds more dramatic than the normal subtle winter bronzing of this cultivar. Are the rootballs being kept moist all the way through? Do poke around in them and check. If it's just winter discoloration the affected leaves will still be fresh and alive in consistency. Crispy and dry indicates mortality.