One out of three going yellow on me . . .

I got 3 awesome Blueberry plants given to me about 3 days ago. They are about 4 weeks old. One of the 3 has a lot of leaves turning yellow. I am thinking I need to add N to this one. But, why would just one turn this way when all are fed the same? They are in CocoNot, under a flourescent strip. I use "House-Garden" ferts. Any thoughts on what I should do?

i would completely flush those pots, unless you know how much they were fed before they were given to you. your pics are a little small to actually see where the yellowing is starting

Thanks, have done a flush. Now just keep my fingers crossed. Will come back with pics and updates.
Thanks again!!

Good luck with the flush, hope your plants make it.