My husband was telling me there is some kind of UV spray for them... I'm not sure exactly what it is but maybe you can do a google search for UV sealers or protectant? Good luck!
I have 2 windows with VERY strong sun hitting at 2 times in the afternoon. If I have anything of color, I either hide it behind a solid object so the sun doesn't get at it or I've used a dangling curtain that cuts the edge off of direct light and filters a bit. This curtain can be milar or something equivalent that flows, catchs the eye, as well, but doesn't divert from your flowers. Not sure, but there may be sprays to effectively treat against sun fade. Best of luck!
