I have tried and tried, but have given upon purple, other than lavender. Lyle has great ones, I think he has the same fading problem, but has put up shade cloth, if I remember. If I grew flowers like lyle, I wouldnt care if it only stayed purple and hour, I hope you find some!
Sandy Holmes sent me a great flower bonus last year, it is dark purple tho, and it does turn brown in the afternoon. So sad. I hope she doesnt see this, but it has to go.