Red robin hedge - losing colour

[PJ.]

Hi there.
I planted some red robin hedging around March and had a few plants left over that I put in pots.
The ones in the ground have lost their "vibrancy" and faded a lot in colour whilst the ones in the pots have stayed strong red and green. In the 2nd picture I have put in one of the pots for contrast.
Am in Ireland so they got loads of rain they are south facing in full sun.
Any ideas what went wrong with the ones on the ground? And best next steps?

Thanks

 

[Anniekay]

We call those Red Tip Photinia in the States. The red tips naturally fade to green. It is only the new growth in spring that comes out red. They don't look diseased at all.