Thuja green giant look at this picture
I bought 13 Thuja Green Giants and planted them back in May 2014. At the time of planting they were 3-4 feet tall, in pots, soil is average to good draining, and I live in zone 7 (north of Ft. Worth). They have grown in height and haven't filled out much at all.
At the time of planting, they were a darker green. Now, 3 months later, they have turned a much lighter shade of green, almost a yellow.
They have not dropped any leaves, no bronze/brown, no insects or any evidence of disease that I can see.
I water the trees about every 2-3 days, between 3 and 10 gallons per tree, depending on what my soil moisture meter says. I water less or more depending on temperature, wind, weather or not it's been sunny, and weather or not it's rained.
My soil meter always indicates dry soil when inserted within several inches of the trunk, but indicates wet soil when inserted a foot diameter from the trunk.
I'm worried about the yellow color. Does anybody have ideas about what's happening?