yellow leaves on phals??

[pamelamcnamara]

Hi all, I am brand new to the forum so please forgive me if this question has already been tackled before (which I am sure it has!). 2 of my phals have leaves that have turned yellow , making the plants look rather unwell. The flowers have been good, but wilting now, presumably coming to the end of flowering time. Roots seem ok although I haven't taken the phals out of the pots to inspect closely. Should I be worried about the yellow leaves and shall I cut them off? Thanks for help in advance. Pam