Jennifer I'm late to this conversation but my 2 cents - some things that I've noticed to impact coloration are when my evenings begin to get colder - it takes a couple of weeks of night time low temps before I notice the changes. Then this past winter our temps were unusually cold and almost all my semps went to a very dark maroon, purple (I had no idea I'd had so many of that color, but because we had near freezing and below freezing temps they got to those deep colors) then once it warms up enough for the soil to maintain some warmth, then the colors fade. So for me here in Seattle there is a Sept. color shift that can last up through Dec. and then if it doesn't get too cold the semps keep that coloration until Feb or March where they begin to get all the pinks and brighter colors (oranges and yellows and bright reds) Again these are just some of my own observations!
