in september i bought 50 cell grown weston red cedar's to grow a hedge but the problem is every plant has turned a grey.

i'll explain everything what i did when i planted them.

i used a bulb digger to dig out all the holes and then i used the same soil and mixed in a little bonemeal and watered
every 2 days for a week. 1 week later i watered in some bio bizz fish mix because some of the plants had a little brown on the bottom of them.
and now all the plants have tuned grey

has anyone got any advice for me or what i should i have done?