Most years swedish aspen turn yellow, much like trembling aspen. A couple times I've seen rose tints in the yellow. But look at my collection this year. Orange, burgundy, bright red? Sometimes all on the same tree? Not all my aspen are affected this way. Overview as to the physiology of different colours. Can this be done deliberately? Edmonton fall colours are primarily yellow. I'd love to be able to do this on command, or at least make it more likely. .